Tracker circuit

Abstract

A switched capacitor circuit (20) of a tracker circuit (1) is provided with switches (S224 and S225). One end of the switch (S224) is connected to one of two electrodes on another side of a flying capacitor (C200), the other end of the switch (S224) is connected to one of two electrodes on one side of the flying capacitor (C202), one end of the switch (S225) is connected to one of two electrodes on the other side of the flying capacitor (C201), and the other end of the switch (S225) is connected to one of two electrodes on the one side of the flying capacitor (C203).

Description

Tracker Circuit

[0001] The present invention relates to a tracker circuit.

[0002] In recent years, power efficiency has been improved by applying envelope tracking (ET) to power amplifier circuits. Patent Document 1 discloses a digital envelope tracking (D-ET) mode that selectively supplies a plurality of discrete voltages based on an envelope signal.

[0003] U.S. Patent No. 9,755,672

[0004] However, the power efficiency of the D-ET mode may decrease as the PAPR (Peak to Average Power Ratio) of the high frequency signal increases.

[0005] Therefore, the present invention provides a tracker circuit that can improve power efficiency in the D-ET mode.

[0006] A tracker circuit according to one aspect of the present invention includes a switched capacitor circuit configured to generate a plurality of discrete voltages from an input voltage, and a power supply modulation circuit configured to selectively output at least one of the generated discrete voltages to a power amplifier, wherein the switched capacitor circuit includes a first flying capacitor, a second flying capacitor, a third flying capacitor, and a fourth flying capacitor, a first smoothing capacitor, a second smoothing capacitor, and a third smoothing capacitor, a first switch, a second switch, a third switch, a fourth switch, a fifth switch, and a fourth switch. a sixth switch, a seventh switch, an eighth switch, a ninth switch, a tenth switch, an eleventh switch, a twelfth switch, a thirteenth switch, and a fourteenth switch, one end of the first switch and one end of the second switch are connected to one of two electrodes of a first flying capacitor, one end of the third switch and one end of the fourth switch are connected to one of two electrodes of a second flying capacitor, one end of the fifth switch and one end of the sixth switch are switchably connected to the other of the two electrodes of the first flying capacitor via the thirteenth switch, and one end of the seventh switch and one end of the eighth switch are switchably connected to the other of the two electrodes of the second flying capacitor via the fourteenth switch and are connected to one of the two electrodes of the fourth flying capacitor; one end of the ninth switch and one end of the tenth switch are connected to the other of the two electrodes of the third flying capacitor; one end of the eleventh switch and one end of the twelfth switch are connected to the other of the two electrodes of the fourth flying capacitor; and the other end of the first switch, the other end of the third switch and two ends of the first smoothing capacitor are connected to the other of the two electrodes of the fourth flying capacitor. One of the electrodes is connected to ground, the other end of the second switch, the other end of the fourth switch, the other end of the fifth switch, and the other end of the seventh switch are connected to the other of the two electrodes of the first smoothing capacitor and one of the two electrodes of the second smoothing capacitor, the other end of the sixth switch, the other end of the eighth switch, the other end of the ninth switch, and the other end of the eleventh switch are connected to the other of the two electrodes of the second smoothing capacitor and one of the two electrodes of the third smoothing capacitor, the other end of the tenth switch and the other end of the twelfth switch are connected to the other of the two electrodes of the third smoothing capacitor, and one end of the thirteenth switch isThe other end of the thirteenth switch is connected to the other of the two electrodes of the first flying capacitor, the other end of the thirteenth switch is connected to one of the two electrodes of the third flying capacitor, one end of the fourteenth switch is connected to the other of the two electrodes of the second flying capacitor, and the other end of the fourteenth switch is connected to one of the two electrodes of the fourth flying capacitor.

[0007] A tracker circuit according to one aspect of the present invention includes a switched capacitor circuit configured to generate a plurality of discrete voltages from an input voltage, and a power supply modulation circuit configured to selectively output at least one of the generated discrete voltages to a power amplifier, wherein the switched capacitor circuit includes a first flying capacitor, a second flying capacitor, a third flying capacitor, and a fourth flying capacitor, a first smoothing capacitor, a second smoothing capacitor, and a third smoothing capacitor, a first switch, a second switch, a third switch, a fourth switch, a fifth switch, and a fourth switch. a sixth switch, a seventh switch, an eighth switch, a ninth switch, a tenth switch, an eleventh switch, a twelfth switch, and a thirteenth switch, one end of the first switch and one end of the second switch are connected to one of two electrodes of the first flying capacitor, one end of the third switch and one end of the fourth switch are connected to one of two electrodes of the second flying capacitor, one end of the fifth switch and one end of the sixth switch are connected to the other of the two electrodes of the first flying capacitor and one of the two electrodes of the third flying capacitor, one end of the seventh switch and one end of the eighth switch are connected to the other of the two electrodes of the first flying capacitor and one of the two electrodes of the third flying capacitor, One end of the ninth switch is connected to the other of the two electrodes of the second flying capacitor and one of the two electrodes of the fourth flying capacitor, one end of the ninth switch and one end of the tenth switch are connected to the other of the two electrodes of the third flying capacitor, one end of the eleventh switch and one end of the twelfth switch are connected to the other of the two electrodes of the fourth flying capacitor, the other end of the first switch, the other end of the third switch and one of the two electrodes of the first smoothing capacitor are connected to each other, and the other end of the second switch, the other end of the fourth switch, the other end of the fifth switch and the other end of the seventh switch are connected to the other of the two electrodes of the fourth flying capacitor. The other end of the sixth switch, the other end of the eighth switch, the other end of the ninth switch and the other end of the eleventh switch are connected to the other of the two electrodes of the second smoothing capacitor and one of the two electrodes of the third smoothing capacitor, the other end of the tenth switch and the other end of the twelfth switch are connected to the other of the two electrodes of the third smoothing capacitor, and one end and the other end of the thirteenth switch are connected to one and the other of the two electrodes of the first smoothing capacitor, the second smoothing capacitor or the third smoothing capacitor, respectively.

[0008] A tracker circuit according to one aspect of the present invention comprises a switched capacitor circuit having a first mode for generating a plurality of first discrete voltages from an input voltage and a second mode for generating a plurality of second discrete voltages from the input voltage, and a power supply modulation circuit configured to selectively output at least one of the generated first discrete voltages or the generated second discrete voltages to a power amplifier, wherein the number of the plurality of first discrete voltages is greater than the number of the plurality of second discrete voltages.

[0009] According to the present invention, power efficiency can be improved in the D-ET mode.

[0010] FIG. 1A is a graph showing an example of a transition of a power supply voltage in an average power tracking (APT) mode. FIG. 1B is a graph showing an example of a transition of a power supply voltage in an analog envelope tracking (A-ET) mode. FIG. 1C is a graph showing an example of a transition of a power supply voltage in a D-ET mode. FIG. 2 is a circuit configuration diagram of a communication device according to a first embodiment. FIG. 3 is a circuit configuration diagram of a tracker circuit according to the first embodiment. FIG. 4A is a circuit configuration diagram showing a connection state in a first phase of a first mode of a switched-capacitor circuit according to the first embodiment. FIG. 4B is a circuit configuration diagram showing a connection state in a second phase of the first mode of a switched-capacitor circuit according to the first embodiment. FIG. 5A is a circuit configuration diagram showing a connection state in a first phase of a second mode of a switched-capacitor circuit according to the first embodiment. FIG. 5B is a circuit configuration diagram showing a connection state in a second phase of a second mode of a switched-capacitor circuit according to the first embodiment. FIG. 6 is a diagram showing an example of a plurality of discrete voltages generated by a switched-capacitor circuit according to the first embodiment. FIG. 7 is a graph showing an example of a time transition of a power supply voltage supplied to a power amplifier by the tracker circuit according to the first embodiment. FIG. 8 is a graph showing an example of a time transition of a power supply voltage supplied to a power amplifier by the tracker circuit according to the first embodiment. FIG. 9 is a circuit configuration diagram of a switched-capacitor circuit according to a modification of the first embodiment. FIG. 10 is a circuit configuration diagram of a communication device according to the second embodiment. FIG. 11 is a circuit configuration diagram of a switched-capacitor circuit according to the second embodiment. FIG. 12A is a circuit configuration diagram showing a connection state in a first phase of a first mode of a switched-capacitor circuit according to the second embodiment. FIG. 12B is a circuit configuration diagram showing a connection state in a second phase of a first mode of a switched-capacitor circuit according to the second embodiment. FIG. 13A is a circuit configuration diagram showing a connection state in a first phase of a second mode of a switched-capacitor circuit according to the second embodiment. FIG. 13B is a circuit configuration diagram showing a connection state in a second phase of a second mode of a switched-capacitor circuit according to the second embodiment.Fig. 14 is a diagram showing an example of a plurality of discrete voltages generated by the switched-capacitor circuit according to the second embodiment. Fig. 15 is a circuit configuration diagram of a switched-capacitor circuit according to a modification of the second embodiment.

[0011] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that the embodiments described below are all comprehensive or specific examples. The numerical values, shapes, materials, components, arrangements and connection forms of the components shown in the following embodiments are merely examples and are not intended to limit the present invention.

[0012] It should be noted that the drawings are schematic diagrams in which emphasis, omission, or adjustment of proportions has been appropriately made to illustrate the present invention, and are not necessarily strictly illustrated, and may differ from the actual shapes, positional relationships, and proportions. In the drawings, the same reference numerals are used to denote substantially the same components, and redundant explanations may be omitted or simplified.

[0013] In a circuit configuration, "connected" includes not only direct connection by connection terminals and / or wiring conductors, but also electrical connection via other circuit elements. "A is switchably connected to B" means that the connection and disconnection between A and B can be switched, and A is connected to B via a switch. "A is connected to B" includes "A is switchably connected to B." "C is connected between A and B" means that one end of C is connected to A and the other end of C is connected to B, and C is arranged in series on the path connecting A and B. "The path connecting A and B" means a path made up of a conductor electrically connecting A to B.

[0014] In the following description, "terminal" means a point where a conductor within an element terminates, although it is understood that terminal can refer to any point on the conductor between elements or the entire conductor, not just a single point, provided that the impedance of the conductor between elements is sufficiently low.

[0015] Furthermore, terms indicating the relationship between elements, such as "parallel" and "perpendicular," terms indicating the shape of elements, such as "rectangle," and numerical ranges do not only represent the strict meaning, but also include a substantially equivalent range, for example, an error of a few percent.

[0016] First, as a technology for highly efficient amplification of high-frequency signals, a tracking mode will be described, in which a power amplifier is supplied with a power supply voltage that is dynamically adjusted over time based on the high-frequency signal. Tracking mode is a mode in which the power supply voltage applied to the power amplifier is dynamically adjusted. There are several types of tracking modes, but here, the APT mode, A-ET mode, and D-ET mode will be described with reference to FIGS. 1A, 1B, and 1C. In FIGS. 1A, 1B, and 1C, the horizontal axis represents time, and the vertical axis represents voltage. Furthermore, the thick solid line represents the power supply voltage, and the thin solid line (waveform) represents the modulation signal.

[0017] 1A is a graph showing an example of the transition of the power supply voltage in the APT mode. In the APT mode of FIG. 1A, the power supply voltage is changed to a plurality of discrete voltage levels in units of one frame based on the average power.

[0018] A frame is a unit that constitutes a high-frequency signal (modulated signal). For example, in 5GNR (5th Generation New Radio) and LTE (Long Term Evolution), a frame includes 10 subframes, each subframe includes multiple slots, and each slot includes multiple symbols. The subframe length is 1 ms, and the frame length is 10 ms.

[0019] A mode in which the voltage level is varied in units of one frame or larger based on the average power is called an APT mode, and is distinguished from a mode in which the voltage level is varied in units smaller than one frame (e.g., subframe, slot, or symbol). For example, a mode in which the voltage level is varied in symbol units is called a symbol power tracking (SPT) mode, and is distinguished from the APT mode.

[0020] 1B is a graph showing an example of the transition of the power supply voltage in the A-ET mode. In the A-ET mode, the envelope of the modulated signal is tracked by continuously varying the power supply voltage based on the envelope signal.

[0021] The envelope signal is a signal that indicates the envelope of the modulated signal. The envelope value is, for example, (I ２ +Q ２ ) where (I, Q) represents a constellation point. A constellation point is a point that represents a digitally modulated signal on a constellation diagram. (I, Q) is determined, for example, by a Baseband Integrated Circuit (BBIC) based on the transmitted information.

[0022] 1C is a graph showing an example of the transition of the power supply voltage in the D-ET mode. In the D-ET mode, the envelope of the modulated signal is tracked by varying the power supply voltage to multiple discrete voltage levels within one frame based on the envelope signal. In other words, in D-ET, the power supply voltage varies at shorter time intervals than in APT.

[0023] (First Embodiment) A first embodiment will be described below.

[0024] [1.1 Circuit Configuration of Communication Device 7] First, the circuit configuration of the communication device 7 according to this embodiment will be described with reference to Fig. 2. Fig. 2 is a circuit configuration diagram of the communication device 7 according to this embodiment.

[0025] 2 is an exemplary circuit configuration, and communication device 7 may be implemented using any of a wide variety of circuit implementations and circuit technologies, and therefore the description of communication device 7 provided below should not be construed as limiting.

[0026] The communication device 7 according to the present embodiment can be used to provide wireless connectivity. For example, the communication device 7 can be implemented in user equipment (UE) in a cellular network, such as a mobile phone, a smartphone, a tablet computer, or a wearable device. In another example, the communication device 7 can be implemented to provide wireless connectivity to Internet of Things (IoT) sensor devices, medical / healthcare devices, cars, unmanned aerial vehicles (UAVs) (also known as drones), and automated guided vehicles (AGVs). In yet another example, the communication device 7 can be implemented to provide wireless connectivity in a wireless access point or wireless hotspot.

[0027] As shown in FIG. 2, the communication device 7 includes a tracker circuit 1, a power amplifier 2, a filter 3, an RFIC (Radio Frequency Integrated Circuit) 5, an antenna 6, and a DC power supply 50.

[0028] The tracker circuit 1 can supply the power supply voltage Vcc to the power amplifier 2 in the D-ET mode. Furthermore, the tracker circuit 1 may supply the power supply voltage Vcc to the power amplifier 2 in the APT mode. As shown in FIG. 2 , the tracker circuit 1 includes a pre-regulator circuit 10, a switched-capacitor circuit 20, a power supply modulation circuit 30, an input terminal 41, an output terminal 42, and a digital control circuit 60.

[0029] The input terminal 41 is a terminal for receiving a DC voltage Vbat from a DC power supply 50. The input terminal 41 is connected to the DC power supply 50 outside the tracker circuit 1, and is connected to the pre-regulator circuit 10 inside the tracker circuit 1.

[0030] The output terminal 42 is a terminal for supplying a power supply voltage Vcc to the power amplifier 2. The output terminal 42 is connected to the power amplifier 2 outside the tracker circuit 1, and is connected to the power supply modulation circuit 30 inside the tracker circuit 1.

[0031] The pre-regulator circuit 10 may also be referred to as a magnetic regulator or a DC (Direct Current) / DC converter. In this embodiment, the pre-regulator circuit 10 is a one-input, one-output buck-boost converter that can convert a DC voltage Vbat to a regulated voltage Vcnv. The pre-regulator circuit 10 may be a buck converter or a boost converter. The pre-regulator circuit 10 can change the regulated voltage Vcnv based on, for example, a control signal from the RFIC 5. A detailed circuit configuration of the pre-regulator circuit 10 will be described later with reference to FIG. 3 . Note that part or all of the pre-regulator circuit 10 may not be included in the tracker circuit 1.

[0032] The switched-capacitor circuit 20 can generate a plurality of discrete voltages V1, V2, V3, V4, V5, and V6, or V2, V3, V4, V5, and V6, based on the regulated voltage Vcnv supplied by the pre-regulator circuit 10. Specifically, the switched-capacitor circuit 20 has a first mode in which the plurality of discrete voltages V1, V2, V3, V4, V5, and V6 (an example of a plurality of first discrete voltages) are generated from the regulated voltage Vcnv, and a second mode in which the plurality of discrete voltages V2, V3, V4, V5, and V6 (an example of a plurality of second discrete voltages) are generated from the regulated voltage Vcnv. In this case, the number of the plurality of discrete voltages V1, V2, V3, V4, V5, and V6 generated in the first mode is greater than the number of the plurality of discrete voltages V2, V3, V4, V5, and V6 generated in the second mode. A detailed circuit configuration of the switched-capacitor circuit 20 will be described later with reference to FIG. 3 .

[0033] The power supply modulation circuit 30 can selectively output at least one of the plurality of discrete voltages generated by the switched capacitor circuit 20 as the power supply voltage Vcc to the power amplifier 2. In other words, the power supply modulation circuit 30 can select at least one voltage from the plurality of discrete voltages and supply the selected voltage to the power amplifier 2. A detailed circuit configuration of the power supply modulation circuit 30 will be described later with reference to FIG. 3 .

[0034] The digital control circuit 60 can control the pre-regulator circuit 10, the switched capacitor circuit 20, and the power supply modulation circuit 30 based on digital control signals from the RFIC 5. Specifically, the digital control circuit 60 can generate and output control signals CS10 and CS20 for controlling switches included in the pre-regulator circuit 10 and the switched capacitor circuit 20, and a control signal CS30 for controlling a switch included in the power supply modulation circuit 30. The circuit configuration of the digital control circuit 60 will be described later using FIG. 3 . Note that part or all of the digital control circuit 60 does not need to be included in the tracker circuit 1.

[0035] The DC power supply 50 is connected to the input terminal 41 of the tracker circuit 1. The DC power supply 50 can supply a DC voltage Vbat to the tracker circuit 1. The DC power supply 50 can be, for example, but is not limited to, a rechargeable battery.

[0036] The power amplifier 2 is connected between the RFIC 5 and the filter 3. Furthermore, the power amplifier 2 is connected to the tracker circuit 1. The power amplifier 2 can amplify the high-frequency signal supplied from the RFIC 5 using the power supply voltage Vcc supplied from the tracker circuit 1.

[0037] The filter 3 is connected between the power amplifier 2 and the antenna 6. The filter 3 is a bandpass filter having a passband including a predetermined band. The predetermined band is a frequency band for a communication system constructed using a radio access technology (RAT), and is defined in advance by a standardization organization (e.g., 3GPP (registered trademark) (3rd Generation Partnership Project) and IEEE (Institute of Electrical and Electronics Engineers)). Examples of communication systems include a 5G NR system, an LTE system, and a WLAN (Wireless Local Area Network) system.

[0038] The antenna 6 transmits the high frequency signal that has passed through the filter 3. The antenna 6 does not necessarily have to be included in the communication device 7.

[0039] 2 is an example, and the circuit configuration of the communication device 7 is not limited to this. For example, the communication device 7 may include a baseband signal processing circuit that processes signals using a frequency band lower than that of high-frequency signals.

[0040] [1.2 Circuit Configuration of Tracker Circuit 1] Next, the circuit configuration of the tracker circuit 1 will be described with reference to Fig. 3. Fig. 3 is a circuit configuration diagram of the tracker circuit 1 according to this embodiment.

[0041] 3 is an example circuit configuration, and tracker circuit 1 may be implemented using any of a wide variety of circuit implementations and circuit techniques, and therefore the description of tracker circuit 1 provided below should not be construed as limiting.

[0042] As described above, the tracker circuit 1 includes the pre-regulator circuit 10, the switched capacitor circuit 20, the power supply modulation circuit 30, and the digital control circuit 60. The tracker circuit 1 may also include a pulse shaping network (PSN) or a filter circuit (neither of which are shown) between the power supply modulation circuit 30 and the output terminal 42.

[0043] The circuit configurations of the pre-regulator circuit 10, the switched capacitor circuit 20, the power supply modulation circuit 30, and the digital control circuit 60 will be described below in order.

[0044] [1.2.1 Circuit Configuration of Pre-regulator Circuit 10] First, the circuit configuration of the pre-regulator circuit 10 will be described with reference to FIG.

[0045] The pre-regulator circuit 10 includes an input terminal T101, an output terminal T102, switches S101 to S104, a power inductor L101, and a capacitor C101.

[0046] The input terminal T101 is a terminal for receiving the DC voltage Vbat. The input terminal T101 is connected to the input terminal 41 outside the pre-regulator circuit 10, and is connected to the switch S101 inside the pre-regulator circuit 10.

[0047] The output terminal T102 is a terminal for supplying the regulated voltage Vcnv to the switched capacitor circuit 20. The output terminal T102 is connected to the input terminal T200 of the switched capacitor circuit 20 outside the pre-regulator circuit 10, and is connected to the switch S103 inside the pre-regulator circuit 10.

[0048] The power inductor L101 is an inductor used to step up and step down the DC voltage Vbat. One end of the power inductor L101 is connected to the switches S101 and S102, and the other end of the power inductor L101 is connected to the switches S103 and S104.

[0049] The switch S101 is connected between the input terminal T101 and one end of the power inductor L101. The switch S102 is connected between one end of the power inductor L101 and ground. In this connection configuration, the DC voltage Vbat can be stepped down by exclusively switching the switches S101 and S102 between open and closed.

[0050] The switch S103 is connected between the other end of the power inductor L101 and the output terminal T102. The switch S104 is connected between the other end of the power inductor L101 and ground. In this connection configuration, the DC voltage Vbat can be boosted by exclusively switching the open and closed states of the switches S103 and S104.

[0051] The capacitor C101 is connected between the path between the switch S103 and the output terminal T102 and ground. Specifically, one of the two electrodes of the capacitor C101 is connected to the switch S103 and the output terminal T102, and the other of the two electrodes of the capacitor C101 is connected to ground.

[0052] 3 is an example and is not limiting. For example, some of the switches S101 to S104 may be replaced with diodes. Also, some or all of the pre-regulator circuit 10 may not be included in the tracker circuit 1.

[0053] [1.2.2 Circuit Configuration of Switched Capacitor Circuit 20] Next, the circuit configuration of the switched capacitor circuit 20 will be described with reference to Fig. 3. The switched capacitor circuit 20 has a ladder-type circuit configuration and can generate a plurality of discrete voltages V1, V2, V3, V4, V5, and V6, or V2, V3, V4, V5, and V6. Specifically, the switched capacitor circuit 20 includes flying capacitors C200 to C209, smoothing capacitors C210 to C215, switches S200 to S225, an input terminal T200, and output terminals T201 to T206. Energy and charge are input from the pre-regulator circuit 10 to node N5 via input terminal T200, and are extracted from nodes N1, N2, N3, N4, N5 and N6 to the power supply modulation circuit 30 via output terminals T201, T202, T203, T204, T205 and T206.

[0054] The input terminal T200 is a terminal for receiving the regulated voltage Vcnv from the pre-regulator circuit 10. The input terminal T200 is connected to the pre-regulator circuit 10 outside the switched capacitor circuit 20, and is connected to a node N5 inside the switched capacitor circuit 20. Note that the node to which the input terminal T200 is connected is not limited to the node N5. The input terminal T200 may be connected to any of the nodes N1, N2, N3, N4, N5, and N6.

[0055] Output terminals T201, T202, T203, T204, T205, and T206 are terminals for supplying a plurality of discrete voltages V1, V2, V3, V4, V5, and V6, respectively, to the power supply modulation circuit 30. The output terminals T201, T202, T203, T204, T205, and T206 are connected to the power supply modulation circuit 30 outside the switched capacitor circuit 20, and are connected to nodes N1, N2, N3, N4, N5, and N6, respectively, within the switched capacitor circuit 20.

[0056] The flying capacitors C200, C201, C202, C203, C204, C205, C206, C207, C208, and C209 are sometimes called transfer capacitors, and are used to step up and / or step down the regulated voltage Vcnv supplied from the pre-regulator circuit 10. More specifically, in the first mode, the flying capacitors C200, C201, C202, C203, C204, C205, C206, C207, C208, and C209 are connected to six nodes N1, N2, N3, N4, N5, and N6 in such a manner that (V6-V5):(V5-V4):(V4-V3):(V3-V2):(V2-V1):(V1-VG)=1:1: Charge is transferred between flying capacitors C200, C201, C202, C203, C204, C205, C206, C207, C208 and C209 and nodes N1, N2, N3, N4, N5, N6 and ground so that V1, V2, V3, V4, V5 and V6 satisfy 1:1:1:1 and V6>V5>V4>V3>V2>V1>VG. In the second mode, flying capacitors C202, C203, C204, C205, C206, C207, C208, and C209 transfer charges between the flying capacitors C202, C203, C204, C205, C206, C207, C208, and C209 and the nodes N2, N3, N4, N5, and N6 and ground so that V2, V3, V4, V5, and V6 satisfy the following relationships at the five nodes N2, N3, N4, N5, and N6: (V6-V5): (V5-V4): (V4-V3): (V3-V2): (V2-VG) = 1:1:1:1:1, and V6 > V5 > V4 > V3 > V2 > VG, where VG represents the ground potential. It should be noted that (V6-V5):(V5-V4):(V4-V3):(V3-V2):(V2-V1):(V1-VG) is not limited to 1:1:1:1:1:1:1, and can be designed to have any ratio (for example, 1:2:3:4:5:6, etc.).

[0057] Flying capacitor C200 is an example of a first flying capacitor. One of two electrodes of flying capacitor C200 is connected to one end of switch S200 and one end of switch S201. The other of the two electrodes of flying capacitor C200 is switchably connected to one end of switch S204 and one end of switch S205 via switch S224.

[0058] Flying capacitor C201 is an example of a second flying capacitor. One of the two electrodes of flying capacitor C201 is connected to one end of switch S202 and one end of switch S203. The other of the two electrodes of flying capacitor C201 is switchably connected to one end of switch S206 and one end of switch S207 via switch S225.

[0059] Flying capacitor C202 is an example of a third flying capacitor. One of two electrodes of flying capacitor C202 is connected to one end of switch S204 and one end of switch S205. The other of two electrodes of flying capacitor C202 is connected to one end of switch S208 and one end of switch S209.

[0060] Flying capacitor C203 is an example of a fourth flying capacitor. One of two electrodes of flying capacitor C203 is connected to one end of switch S206 and one end of switch S207. The other of two electrodes of flying capacitor C203 is connected to one end of switch S210 and one end of switch S211.

[0061] Flying capacitor C204 is an example of a fifth flying capacitor. One of the two electrodes of flying capacitor C204 is connected to one end of switch S208 and one end of switch S209. The other of the two electrodes of flying capacitor C204 is connected to one end of switch S212 and one end of switch S213.

[0062] Flying capacitor C205 is an example of a sixth flying capacitor. One of two electrodes of flying capacitor C205 is connected to one end of switch S210 and one end of switch S211. The other of two electrodes of flying capacitor C205 is connected to one end of switch S214 and one end of switch S215.

[0063] One of the two electrodes of the flying capacitor C206 is connected to one end of the switch S212 and one end of the switch S213. The other of the two electrodes of the flying capacitor C206 is connected to one end of the switch S216 and one end of the switch S217.

[0064] One of the two electrodes of the flying capacitor C207 is connected to one end of the switch S214 and one end of the switch S215. The other of the two electrodes of the flying capacitor C207 is connected to one end of the switch S218 and one end of the switch S219.

[0065] One of the two electrodes of the flying capacitor C208 is connected to one end of the switch S216 and one end of the switch S217. The other of the two electrodes of the flying capacitor C208 is connected to one end of the switch S220 and one end of the switch S221.

[0066] One of the two electrodes of the flying capacitor C209 is connected to one end of the switch S218 and one end of the switch S219. The other of the two electrodes of the flying capacitor C209 is connected to one end of the switch S222 and one end of the switch S223.

[0067] Smoothing capacitors C210, C211, C212, C213, C214 and C215 are used to hold and smooth the discrete voltages V1, V2, V3, V4, V5 and V6 at nodes N1, N2, N3, N4, N5 and N6.

[0068] The smoothing capacitor C210 is an example of a first smoothing capacitor and is connected between the node N1 and ground. Specifically, one of the two electrodes of the smoothing capacitor C210 is connected to the node N1. Meanwhile, the other of the two electrodes of the smoothing capacitor C210 is connected to ground.

[0069] The smoothing capacitor C211 is an example of a second smoothing capacitor and is connected between the nodes N1 and N2. Specifically, one of the two electrodes of the smoothing capacitor C211 is connected to the node N2. Meanwhile, the other of the two electrodes of the smoothing capacitor C211 is connected to the node N1.

[0070] The smoothing capacitor C212 is an example of a third smoothing capacitor and is connected between the nodes N2 and N3. Specifically, one of the two electrodes of the smoothing capacitor C212 is connected to the node N3. Meanwhile, the other of the two electrodes of the smoothing capacitor C212 is connected to the node N2.

[0071] The smoothing capacitor C213 is an example of a fourth smoothing capacitor and is connected between the nodes N3 and N4. Specifically, one of the two electrodes of the smoothing capacitor C213 is connected to the node N4. Meanwhile, the other of the two electrodes of the smoothing capacitor C213 is connected to the node N3.

[0072] The smoothing capacitor C214 is connected between the nodes N4 and N5. Specifically, one of the two electrodes of the smoothing capacitor C214 is connected to the node N5. Meanwhile, the other of the two electrodes of the smoothing capacitor C214 is connected to the node N4.

[0073] The smoothing capacitor C215 is connected between the nodes N5 and N6. Specifically, one of the two electrodes of the smoothing capacitor C215 is connected to the node N6. Meanwhile, the other of the two electrodes of the smoothing capacitor C215 is connected to the node N5.

[0074] The switch S200 is an example of a first switch and is connected between the flying capacitor C200 and ground. Specifically, one end of the switch S200 is connected to one of the two electrodes of the flying capacitor C200. Meanwhile, the other end of the switch S200 is connected to ground.

[0075] The switch S201 is an example of a second switch and is connected between the flying capacitor C200 and the node N1. Specifically, one end of the switch S201 is connected to one of the two electrodes of the flying capacitor C200. Meanwhile, the other end of the switch S201 is connected to the node N1.

[0076] The switch S202 is an example of a third switch and is connected between the flying capacitor C201 and ground. Specifically, one end of the switch S202 is connected to one of the two electrodes of the flying capacitor C201. Meanwhile, the other end of the switch S202 is connected to ground.

[0077] The switch S203 is an example of a fourth switch and is connected between the flying capacitor C201 and the node N1. Specifically, one end of the switch S203 is connected to one of the two electrodes of the flying capacitor C201. Meanwhile, the other end of the switch S203 is connected to the node N1.

[0078] The switch S204 is an example of a fifth switch and is connected between the flying capacitors C200 and C202 and the node N1. Specifically, one end of the switch S204 is switchably connected to the other of the two electrodes of the flying capacitor C200 via the switch S224, and is also connected to one of the two electrodes of the flying capacitor C202. Meanwhile, the other end of the switch S204 is connected to the node N1.

[0079] The switch S205 is an example of a sixth switch and is connected between the flying capacitors C200 and C202 and the node N2. Specifically, one end of the switch S205 is switchably connected to the other of the two electrodes of the flying capacitor C200 via the switch S224, and is also connected to one of the two electrodes of the flying capacitor C202. Meanwhile, the other end of the switch S205 is connected to the node N2.

[0080] The switch S206 is an example of a seventh switch and is connected between the flying capacitors C201 and C203 and the node N1. Specifically, one end of the switch S206 is switchably connected to the other of the two electrodes of the flying capacitor C201 via the switch S225, and is also connected to one of the two electrodes of the flying capacitor C203. Meanwhile, the other end of the switch S206 is connected to the node N1.

[0081] The switch S207 is an example of an eighth switch and is connected between the flying capacitors C201 and C203 and the node N2. Specifically, one end of the switch S207 is switchably connected to the other of the two electrodes of the flying capacitor C201 via the switch S225, and is also connected to one of the two electrodes of the flying capacitor C203. Meanwhile, the other end of the switch S207 is connected to the node N2.

[0082] The switch S208 is an example of a ninth switch and is connected between the flying capacitors C202 and C204 and the node N2. Specifically, one end of the switch S208 is connected to the other of the two electrodes of the flying capacitor C202 and one of the two electrodes of the flying capacitor C204. Meanwhile, the other end of the switch S208 is connected to the node N2.

[0083] The switch S209 is an example of a tenth switch and is connected between the flying capacitors C202 and C204 and the node N3. Specifically, one end of the switch S209 is connected to the other of the two electrodes of the flying capacitor C202 and one of the two electrodes of the flying capacitor C204. Meanwhile, the other end of the switch S209 is connected to the node N3.

[0084] The switch S210 is an example of an eleventh switch and is connected between the flying capacitors C203 and C205 and the node N2. Specifically, one end of the switch S210 is connected to the other of the two electrodes of the flying capacitor C203 and one of the two electrodes of the flying capacitor C205. Meanwhile, the other end of the switch S210 is connected to the node N2.

[0085] The switch S211 is an example of a twelfth switch and is connected between the flying capacitors C203 and C205 and the node N3. Specifically, one end of the switch S211 is connected to the other of the two electrodes of the flying capacitor C203 and one of the two electrodes of the flying capacitor C205. Meanwhile, the other end of the switch S211 is connected to the node N3.

[0086] The switch S212 is an example of a fifteenth switch and is connected between the flying capacitors C204 and C206 and the node N3. Specifically, one end of the switch S212 is connected to the other of the two electrodes of the flying capacitor C204 and one of the two electrodes of the flying capacitor C206. Meanwhile, the other end of the switch S212 is connected to the node N3.

[0087] The switch S213 is an example of a sixteenth switch and is connected between the flying capacitors C204 and C206 and the node N4. Specifically, one end of the switch S213 is connected to the other of the two electrodes of the flying capacitor C204 and one of the two electrodes of the flying capacitor C206. Meanwhile, the other end of the switch S213 is connected to the node N4.

[0088] The switch S214 is an example of a seventeenth switch and is connected between the flying capacitors C205 and C207 and the node N3. Specifically, one end of the switch S214 is connected to the other of the two electrodes of the flying capacitor C205 and one of the two electrodes of the flying capacitor C207. Meanwhile, the other end of the switch S214 is connected to the node N3.

[0089] The switch S215 is an example of an 18th switch and is connected between the flying capacitors C205 and C207 and the node N4. Specifically, one end of the switch S215 is connected to the other of the two electrodes of the flying capacitor C205 and one of the two electrodes of the flying capacitor C207. Meanwhile, the other end of the switch S215 is connected to the node N4.

[0090] The switch S216 is connected between the flying capacitors C206 and C208 and the node N4. Specifically, one end of the switch S216 is connected to the other of the two electrodes of the flying capacitor C206 and one of the two electrodes of the flying capacitor C208. Meanwhile, the other end of the switch S216 is connected to the node N4.

[0091] The switch S217 is connected between the flying capacitors C206 and C208 and the node N5. Specifically, one end of the switch S217 is connected to the other of the two electrodes of the flying capacitor C206 and one of the two electrodes of the flying capacitor C208. Meanwhile, the other end of the switch S217 is connected to the node N5.

[0092] The switch S218 is connected between the flying capacitors C207 and C209 and the node N4. Specifically, one end of the switch S218 is connected to the other of the two electrodes of the flying capacitor C207 and one of the two electrodes of the flying capacitor C209. Meanwhile, the other end of the switch S218 is connected to the node N4.

[0093] The switch S219 is connected between the flying capacitors C207 and C209 and the node N5. Specifically, one end of the switch S219 is connected to the other of the two electrodes of the flying capacitor C207 and one of the two electrodes of the flying capacitor C209. Meanwhile, the other end of the switch S219 is connected to the node N5.

[0094] The switch S220 is connected between the flying capacitor C208 and a node N5. Specifically, one end of the switch S220 is connected to the other of the two electrodes of the flying capacitor C208. Meanwhile, the other end of the switch S220 is connected to the node N5.

[0095] The switch S221 is connected between the flying capacitor C208 and a node N6. Specifically, one end of the switch S221 is connected to the other of the two electrodes of the flying capacitor C208. Meanwhile, the other end of the switch S221 is connected to the node N6.

[0096] The switch S222 is connected between the flying capacitor C209 and a node N5. Specifically, one end of the switch S222 is connected to the other of the two electrodes of the flying capacitor C209. Meanwhile, the other end of the switch S222 is connected to the node N5.

[0097] The switch S223 is connected between the flying capacitor C209 and a node N6. Specifically, one end of the switch S223 is connected to the other of the two electrodes of the flying capacitor C209. Meanwhile, the other end of the switch S223 is connected to the node N6.

[0098] The switch S224 is an example of a thirteenth switch, and is connected between the flying capacitor C200 and the flying capacitor C202 and the switches S204 and S205. Specifically, one end of the switch S224 is connected to the other of the two electrodes of the flying capacitor C200. Meanwhile, the other end of the switch S224 is connected to one of the two electrodes of the flying capacitor C202, one end of the switch S204, and one end of the switch S205. When the switch S224 is open, the flying capacitor C200 is not connected to the flying capacitor C202.

[0099] The switch S225 is an example of a fourteenth switch, and is connected between the flying capacitor C201 and the flying capacitor C203 and the switches S206 and S207. Specifically, one end of the switch S225 is connected to the other of the two electrodes of the flying capacitor C201. Meanwhile, the other end of the switch S225 is connected to one of the two electrodes of the flying capacitor C203, one end of the switch S206, and one end of the switch S207. When the switch S225 is open, the flying capacitor C201 is not connected to the flying capacitor C203.

[0100] [1.2.3 Circuit Configuration of Power Supply Modulation Circuit 30] Next, the circuit configuration of the power supply modulation circuit 30 will be described with reference to Fig. 3. The power supply modulation circuit 30 includes input terminals T301 to T306, an output terminal T307, and switches S301 to S306.

[0101] Input terminals T301, T302, T303, T304, T305, and T306 are terminals for receiving a plurality of discrete voltages V1, V2, V3, V4, V5, and V6 generated by the switched capacitor circuit 20. The input terminals T301, T302, T303, T304, T305, and T306 are connected to output terminals T201, T202, T203, T204, T205, and T206 of the switched capacitor circuit 20, respectively, outside the power supply modulation circuit 30, and are connected to switches S301, S302, S303, S304, S305, and S306, respectively, within the power supply modulation circuit 30.

[0102] Output terminal T307 is a terminal for selectively supplying at least one of a plurality of discrete voltages V1, V2, V3, V4, V5, and V6 to power amplifier 2. Output terminal T307 is connected to output terminal 42 outside power supply modulation circuit 30, and is connected to switches S301, S302, S303, S304, S305, and S306 inside power supply modulation circuit 30.

[0103] The switch S301 is connected between the input terminal T301 and the output terminal T307. The switch S302 is connected between the input terminal T302 and the output terminal T307. The switch S303 is connected between the input terminal T303 and the output terminal T307. The switch S304 is connected between the input terminal T304 and the output terminal T307. The switch S305 is connected between the input terminal T305 and the output terminal T307. The switch S306 is connected between the input terminal T306 and the output terminal T307.

[0104] These switches S301, S302, S303, S304, S305, and S306 are switched open and closed (on and off) by a control signal CS30 from the digital control circuit 60. In this embodiment, the switches S301, S302, S303, S304, S305, and S306 are controlled to be exclusively on. That is, only one of the switches S301, S302, S303, S304, S305, and S306 is closed, and the remaining switches S301, S302, S303, S304, S305, and S306 are all controlled to be open. This allows the power supply modulation circuit 30 to supply one voltage selected from a plurality of discrete voltages (V1, V2, V3, V4, V5, and V6) to the power amplifier 2.

[0105] 3 is an example and is not limited to this. In particular, the switches S301, S302, S303, S304, S305, and S306 may have any configuration and may be controlled in any manner as long as they can selectively connect at least one of the six input terminals T301, T302, T303, T304, T305, and T306 to the output terminal T307. For example, two of the switches S301, S302, S303, S304, S305, and S306 may be closed, and the remaining four of the switches S301, S302, S303, S304, S305, and S306 may be opened.

[0106] [1.2.4 Circuit Configuration of Digital Control Circuit 60] Next, the circuit configuration of the digital control circuit 60 will be described with reference to Fig. 3. The digital control circuit 60 includes a first controller 61 and a second controller 62.

[0107] The first controller 61 processes the serial data signals (CLK, DATA) supplied from the RFIC 5 and can generate control signals CS10 and CS20 for controlling the pre-regulator circuit 10 and the switched capacitor circuit 20. The control signal CS10 is a signal for controlling the opening and closing of switches S101 to S104 included in the pre-regulator circuit 10. The control signal CS20 is a signal for controlling the opening and closing of switches S200 to S225 included in the switched capacitor circuit 20. A feedback signal for controlling the pre-regulator circuit 10 may be input to the first controller 61.

[0108] The serial data signal may be, for example, a source synchronous digital control signal. Alternatively, a clock-embedded digital control signal may be used as the serial data signal. The first controller 61 may also generate a control signal for controlling the power supply modulation circuit 30.

[0109] In this embodiment, one set of clock signal (CLK) and data signal (DATA) is shared by the pre-regulator circuit 10 and the switched-capacitor circuit 20, but this is not limiting. For example, one set of clock signal and data signal may be used individually by the pre-regulator circuit 10 and the switched-capacitor circuit 20.

[0110] The second controller 62 processes the parallel data signals supplied from the RFIC 5 and generates a control signal CS30 for controlling the power supply modulation circuit 30. Examples of the parallel data signals include digital control level (DCL) signals (DCL1, DCL2, and DCL3). The DCL signals (DCL1, DCL2, and DCL3) are generated by the RFIC 5 based on the envelope signal of the high-frequency signal. The control signal CS30 is a signal for controlling the opening and closing of switches S301, S302, S303, S304, S305, and S306 included in the power supply modulation circuit 30.

[0111] Each of the DCL signals (DCL1, DCL2, DCL3) is a 1-bit signal. Each of the multiple discrete voltages V1, V2, V3, V4, V5, and V6 is represented by a combination of two 1-bit signals. For example, V1, V2, V3, V4, V5, and V6 are represented by "000," "001," "010," "011," "110," and "111," respectively. Gray code may be used to represent the voltage levels.

[0112] In this embodiment, three DCL signals are used to control the power supply modulation circuit 30, but the number of DCL signals is not limited to this. For example, any number of DCL signals, such as one, two, or four or more, may be used depending on the number of voltage levels that each power supply modulation circuit 30 can select. Furthermore, the parallel data signals used to control the power supply modulation circuit 30 are not limited to DCL signals.

[0113] [1.3 Control Method of Switched Capacitor Circuit 20] Next, a control method of the switched capacitor circuit 20 according to this embodiment will be described with reference to FIGS. 4A, 4B, 5A, and 5B.

[0114] [1.3.1 First Mode] First, the first mode will be described with reference to Fig. 4A and Fig. 4B. Fig. 4A is a circuit diagram showing a connection state in the first phase of the first mode of the switched-capacitor circuit 20 according to this embodiment. Fig. 4B is a circuit diagram showing a connection state in the second phase of the first mode of the switched-capacitor circuit 20 according to this embodiment.

[0115] The first mode is a mode in which the switched capacitor circuit 20 generates six discrete voltages V1, V2, V3, V4, V5, and V6. That is, in the first mode, the switched capacitor circuit 20 forms six stages of switched capacitors.

[0116] In the first mode, the first and second phases are alternately repeated based on a control signal CS20 from the digital control circuit 60.

[0117] In the first phase of the first mode, as shown in Figure 4A, a first set of switches S200, S203, S204, S207, S208, S211, S212, S215, S216, S219, S220, and S223 are closed, and a second set of switches S201, S202, S205, S206, S209, S210, S213, S214, S217, S218, S221, and S222 are open. Additionally, switches S224 and S225 are closed.

[0118] In the second phase of the first mode, as shown in Figure 4B, a first set of switches S200, S203, S204, S207, S208, S211, S212, S215, S216, S219, S220, and S223 are open, and a second set of switches S201, S202, S205, S206, S209, S210, S213, S214, S217, S218, S221, and S222 are closed. Additionally, switches S224 and S225 are closed.

[0119] Thus, in the first mode, the first set of switches and the second set of switches alternate between open and closed during the first and second phases, while switches S224 and S225 remain closed during the first and second phases.

[0120] By repeating the first and second phases, the flying capacitors C200, C201, C202, C203, C204, C205, C206, C207, C208, and C209 can be charged and discharged in a complementary manner. For example, in one of the first and second phases, the flying capacitors C200, C202, C204, C206, and C208 charge the smoothing capacitors C210, C211, C212, C213, C214, and C215, and in the other of the first and second phases, the flying capacitors C201, C203, C205, C207, and C209 charge the smoothing capacitors C210, C211, C212, C213, C214, and C215. In other words, smoothing capacitors C210, C211, C212, C213, C214, and C215 are always charged from any of flying capacitors C200, C201, C202, C203, C204, C205, C206, C207, C208, and C209, so even if a current flows from any of nodes N1, N2, N3, N4, N5, and N6 to power supply modulation circuit 30 at high speed, charge is replenished at high speed to any of nodes N1, N2, N3, N4, N5, and N6, and fluctuations in the potential of nodes N1, N2, N3, N4, N5, and N6 can be suppressed.

[0121] By operating in this manner, the switched capacitor circuit 20 can maintain approximately equal voltages across each of the smoothing capacitors C210, C211, C212, C213, C214, and C215. Specifically, at six nodes N1, N2, N3, N4, N5, and N6 labeled V1, V2, V3, V4, V5, and V6, a plurality of discrete voltages V1, V2, V3, V4, V5, and V6 that satisfy the following relationship: (V6-V5):(V5-V4):(V4-V3):(V3-V2):(V2-V1):(V1-VG)=1:1:1:1:1:1:1. For example, if the regulated voltage Vcnv supplied from the pre-regulator circuit 10 is 5V, the switched capacitor circuit 20 can generate six discrete voltages (V1, V2, V3, V4, V5, V6) (1V, 2V, 3V, 4V, 5V, 6V).

[0122] [1.3.2 Second Mode] Next, the second mode will be described with reference to Fig. 5A and Fig. 5B. Fig. 5A is a circuit diagram showing a connection state in the first phase of the second mode of the switched-capacitor circuit 20 according to this embodiment. Fig. 5B is a circuit diagram showing a connection state in the second phase of the second mode of the switched-capacitor circuit 20 according to this embodiment.

[0123] The second mode is a mode in which the switched capacitor circuit 20 generates five discrete voltages V2, V3, V4, V5, and V6. That is, in the second mode, the switched capacitor circuit 20 forms a five-stage switched capacitor.

[0124] In the second mode, the first and second phases are alternately repeated based on a control signal CS20 from the digital control circuit 60.

[0125] In the first phase of the second mode, as shown in Figure 5A, a third set of switches S204, S207, S208, S211, S212, S215, S216, S219, S220, and S223 are closed, and a fourth set of switches S205, S206, S209, S210, S213, S214, S217, S218, S221, and S222 are open. Additionally, switches S200, S201, S202, and S203 are closed, and switches S224 and S225 are open.

[0126] In the second phase of the second mode, as shown in Figure 5B, a third set of switches S204, S207, S208, S211, S212, S215, S216, S219, S220, and S223 are open, and a fourth set of switches S205, S206, S209, S210, S213, S214, S217, S218, S221, and S222 are closed. Additionally, switches S200, S201, S202, and S203 are closed, and switches S224 and S225 are open.

[0127] Thus, in the second mode, the third set of switches and the fourth set of switches alternate between open and closed during the first and second phases, while switches S200, S201, S202, and S203 remain closed during the first and second phases, and switches S224 and S225 remain open during the first and second phases.

[0128] By repeating the first and second phases, the flying capacitors C202, C203, C204, C205, C206, C207, C208, and C209 can be charged and discharged in a complementary manner. For example, in one of the first and second phases, the flying capacitors C202, C204, C206, and C208 charge the smoothing capacitors C211, C212, C213, C214, and C215, and in the other of the first and second phases, the flying capacitors C203, C205, C207, and C209 charge the smoothing capacitors C211, C212, C213, C214, and C215. In other words, smoothing capacitors C211, C212, C213, C214, and C215 are always charged from any of flying capacitors C202, C203, C204, C205, C206, C207, C208, and C209, so even if a current flows from any of nodes N2, N3, N4, N5, and N6 to power supply modulation circuit 30 at high speed, charge is replenished at high speed to any of nodes N2, N3, N4, N5, and N6, and fluctuations in the potential of nodes N2, N3, N4, N5, and N6 can be suppressed.

[0129] By operating in this manner, the switched capacitor circuit 20 can maintain approximately equal voltages across each of the smoothing capacitors C211, C212, C213, C214, and C215. Specifically, at five nodes N2, N3, N4, N5, and N6 labeled V2, V3, V4, V5, and V6, a plurality of discrete voltages V2, V3, V4, V5, and V6 satisfying the following relationship: (V6-V5):(V5-V4):(V4-V3):(V3-V2):(V2-VG)=1:1:1:1:1. For example, when the regulated voltage Vcnv supplied from the pre-regulator circuit 10 is 5 V, the switched capacitor circuit 20 can generate five discrete voltages (V2, V3, V4, V5, and V6) of 1.25 V, 2.5 V, 3.75 V, 5 V, and 6.25 V in the second mode.

[0130] [1.4 Multiple Discrete Voltages Generated in First Mode and Second Mode] Next, multiple discrete voltages generated by the switched-capacitor circuit 20 according to this embodiment will be described with reference to Fig. 6. Fig. 6 is a diagram showing an example of multiple discrete voltages generated by the switched-capacitor circuit 20 according to this embodiment. In Fig. 6, the power supply voltage Vcc corresponding to the peak power of the high-frequency signal amplified by the power amplifier 2 is 6 V.

[0131] For example, in the first mode, the pre-regulator circuit 10 supplies a regulated voltage Vcnv of 5 V to the switched capacitor circuit 20. In this case, the switched capacitor circuit 20 can generate six discrete voltages (1 V, 2 V, 3 V, 4 V, 5 V, and 6 V).

[0132] For example, in the second mode, the pre-regulator circuit 10 supplies a regulated voltage Vcnv of 4.8 V to the switched capacitor circuit 20. In this case, the switched capacitor circuit 20 can generate five discrete voltages (1.2 V, 2.4 V, 3.6 V, 4.8 V, and 6 V).

[0133] [1.5 Power Supply Voltages Supplied to Power Amplifier 2] Here, the power supply voltages Vcc1 and Vcc2 supplied to the power amplifier 2 in the first and second modes will be described with reference to FIGS. 7 and 8. FIG.

[0134] [1.5.1 Power Supply Voltage for First High-Frequency Signal Having Larger PAPR] First, the power supply voltage Vcc supplied to amplify a first high-frequency signal having a PAPR equal to or greater than a threshold will be described with reference to FIG. 7. FIG. 7 is a graph showing an example of the temporal progression of power supply voltages Vcc1 and Vcc2 that can be supplied to the power amplifier 2 by the tracker circuit 1 according to this embodiment. In FIG. 7, the horizontal axis represents time. The solid line represents the power supply voltage Vcc1 that can be supplied in the first mode, and the dashed line represents the power supply voltage Vcc2 that can be supplied in the second mode. The envelope signal RF1 represents the envelope signal of the first high-frequency signal.

[0135] 7 , in both the first mode and the second mode, three discrete voltages V4, V5, and V6, which are higher than a predetermined voltage (e.g., a power supply voltage corresponding to the average power of the first high-frequency signal), among a plurality of discrete voltages, can be used as the power supply voltages Vcc1 and Vcc2. In such a case, the power supply voltage Vcc2 that can be supplied in the second mode can track the envelope signal RF1 of the first high-frequency signal to a lower voltage than the power supply voltage Vcc1 that can be supplied in the first mode. Therefore, in FIG. 7 , the second mode can achieve higher power efficiency than the first mode. In other words, when the PAPR of the high-frequency signal amplified by the power amplifier 2 is equal to or higher than a threshold, applying the second mode to the switched-capacitor circuit 20 can improve power efficiency.

[0136] In this case, a value that is empirically and / or experimentally determined in advance can be used as the threshold value. The PAPR of the high frequency signal can be measured using an RF detector (RF Power Detector).

[0137] [1.5.2 Power Supply Voltage for Second High-Frequency Signal Having Smaller PAPR] Next, the power supply voltage Vcc supplied to amplify the second high-frequency signal having a PAPR less than the threshold will be described with reference to FIG. 8 . FIG. 8 is a graph showing an example of the time progression of the power supply voltages Vcc1 and Vcc2 that can be supplied to the power amplifier 2 by the tracker circuit 1 according to this embodiment. In FIG. 8 , the horizontal axis represents time. The solid line represents the power supply voltage Vcc1 that can be supplied in the first mode, and the dashed line represents the power supply voltage Vcc2 that can be supplied in the second mode. The envelope signal RF2 represents the envelope signal of the second high-frequency signal.

[0138] 8, in the first mode, three discrete voltages V4, V5, and V6 that are higher than a predetermined voltage (e.g., a power supply voltage corresponding to the average power of the second high-frequency signal) are used among the plurality of discrete voltages V1, V2, V3, V4, V5, and V6, while in the second mode, two discrete voltages V5 and V6 that are higher than the predetermined voltage are used among the plurality of discrete voltages V2, V3, V4, V5, and V6.

[0139] In this case, the power supply voltage Vcc1 that can be supplied in the first mode can track the envelope signal RF2 of the second high frequency signal to a lower voltage than the power supply voltage Vcc2 that can be supplied in the second mode. Therefore, in Fig. 8, the first mode can achieve higher power efficiency than the second mode. In other words, when the PAPR of the high frequency signal amplified by the power amplifier 2 is less than a threshold, applying the first mode to the switched-capacitor circuit 20 can improve power efficiency.

[0140] 7 and 8 are illustrative embodiments and are not intended to limit the combinations of discrete voltages that can be supplied to the power amplifier 2 in the first and second modes. While periods in which three discrete voltages V4, V5, and V6 are supplied among the plurality of discrete voltages are shown in FIGS. 7 and 8, other discrete voltages V1, V2, and V3 may be supplied in other periods. In other words, the combinations of discrete voltages supplied to the power amplifier 2 are not limited to the examples in FIGS. 7 and 8.

[0141] The relationship between the PAPR and the first and second modes is not limited to the above. For example, when the PAPR is equal to or greater than a threshold, the first mode capable of generating more discrete voltages may be applied to the switched capacitor circuit 20, and when the PAPR is less than the threshold, the second mode capable of generating fewer discrete voltages may be applied to the switched capacitor circuit 20.

[0142] Furthermore, for example, the first mode and the second mode may be switched depending on the modulation method of the high-frequency signal. For example, when the bit rate of the modulation method of the high-frequency signal is equal to or greater than a threshold, the second mode capable of generating fewer discrete voltages may be applied to the switched capacitor circuit 20. When the bit rate of the modulation method of the high-frequency signal is less than the threshold, the first mode capable of generating more discrete voltages may be applied to the switched capacitor circuit 20. Conversely, when the bit rate of the modulation method of the high-frequency signal is equal to or greater than the threshold, the first mode may be applied to the switched capacitor circuit 20, and when the bit rate of the modulation method of the high-frequency signal is less than the threshold, the second mode may be applied to the switched capacitor circuit 20.

[0143] The bit rate of a modulation scheme for a high frequency signal can be determined by measuring the constellation points of the high frequency signal. The higher the bit rate of the modulation scheme, the greater the number of separable constellation points. In general, Quadrature Amplitude Modulation (QAM) (e.g., 256QAM, 64QAM, 16QAM, etc.) has a higher bit rate and a larger PAPR than Phase Shift Keying (PSK) (e.g., Quadrature Phase Shift Keying (QPSK) and Binary Phase Shift Keying (BPSK)).

[0144] [1.6 Summary] As described above, the tracker circuit 1 according to this embodiment includes the switched capacitor circuit 20 configured to generate a plurality of discrete voltages from an input voltage, and the power supply modulation circuit 30 configured to selectively output at least one of the generated plurality of discrete voltages to the power amplifier 2. The switched capacitor circuit 20 includes flying capacitors C200, C201, C202, and C203, smoothing capacitors C210, C211, and C212, and switches S200, S201, S202, S203, S204, S205, S206, S207, S208, S209, S301, S301, S302, S303, S304, S305, S306, S307, S308, S309, S401, S410, S411, S412, S413, S414, S415, S416, S417, S418, S420, S421, S422, S423, S424, S425, S426, S427, S428, S429, S500, S501, S502, S503, S504, S505, S506, S507, S508, S510, S511, S512, S513, S514, S515, S516, S517, S520 One end of the switch S200 and one end of the switch S201 are connected to one of the two electrodes of the flying capacitor C200, one end of the switch S202 and one end of the switch S203 are connected to one of the two electrodes of the flying capacitor C201, one end of the switch S204 and one end of the switch S205 are switchably connected to the other of the two electrodes of the flying capacitor C200 via the switch S224 and are connected to one of the two electrodes of the flying capacitor C202, One end of the switch S206 and one end of the switch S207 are switchably connected to the other of the two electrodes of the flying capacitor C201 via the switch S225, and are connected to one of the two electrodes of the flying capacitor C203, one end of the switch S208 and one end of the switch S209 are connected to the other of the two electrodes of the flying capacitor C202, one end of the switch S210 and one end of the switch S211 are connected to the other of the two electrodes of the flying capacitor C203, and the other end of the switch S200, the other end of the switch S202 and one end of the smoothing capacitor C203 are connected to the other of the two electrodes of the flying capacitor C203. One of the two electrodes of C210 is connected to ground, the other end of switch S201, the other end of switch S203, the other end of switch S204, and the other end of switch S206 are connected to the other of the two electrodes of smoothing capacitor C210 and one of the two electrodes of smoothing capacitor C211, the other end of switch S205, the other end of switch S207, the other end of switch S208, and the other end of switch S210 are connected to the other of the two electrodes of smoothing capacitor C211 and one of the two electrodes of smoothing capacitor C212, and the other end of switch S209 and the other end of switch S211 are connected to ground.One end of the switch S224 is connected to the other of the two electrodes of the flying capacitor C200, the other end of the switch S224 is connected to one of the two electrodes of the flying capacitor C202, one end of the switch S225 is connected to the other of the two electrodes of the flying capacitor C201, and the other end of the switch S225 is connected to one of the two electrodes of the flying capacitor C203.

[0145] According to this, the connection between the flying capacitors C200 and C202 can be disconnected by the switch S224, and the connection between the flying capacitors C201 and C203 can be disconnected by the switch S225. Therefore, it is possible to switch between enabling and disabling the flying capacitors C200 and C201 in the switched capacitor circuit 20. As a result, it is possible to increase the number of variations in the number of discrete voltages that can be generated by the switched capacitor circuit 20. This makes it possible to generate a plurality of discrete voltages that are more suitable for the high-frequency signal amplified by the power amplifier 2, thereby improving power efficiency in the D-ET mode.

[0146] For example, in the tracker circuit 1 according to this embodiment, when the PAPR of the high frequency signal amplified by the power amplifier 2 is less than a threshold, the switches S224 and S225 may be kept closed, and when the PAPR is equal to or greater than the threshold, the switches S200, S201, S202, and S203 may be kept closed, and the switches S224 and S225 may be kept open.

[0147] This allows the number of discrete voltages to be reduced when the PAPR of the high frequency signal amplified by the power amplifier 2 is large. For the same peak power of the high frequency signal, the average power of a high frequency signal with a larger PAPR will be lower than the average power of a high frequency signal with a smaller PAPR. As shown in FIG. 7 , when the number of voltages that can be supplied in the D-ET mode is limited, a smaller number of discrete voltages allows the envelope signal of the high frequency signal to be tracked down to a lower voltage. Therefore, when the PAPR of the high frequency signal amplified by the power amplifier 2 is large, reducing the number of discrete voltages can improve power efficiency in the D-ET mode.

[0148] In addition, the tracker circuit 1 of this embodiment includes a switched capacitor circuit 20 having a first mode for generating a plurality of first discrete voltages from an input voltage and a second mode for generating a plurality of second discrete voltages from the input voltage, and a power supply modulation circuit 30 configured to selectively output at least one of the generated plurality of first discrete voltages or the plurality of second discrete voltages to the power amplifier 2, wherein the number of the plurality of first discrete voltages is greater than the number of the plurality of second discrete voltages.

[0149] This allows switching the number of discrete voltages generated by the switched capacitor circuit 20. Therefore, it becomes possible to generate discrete voltages that are more suitable for the high frequency signal amplified by the power amplifier 2, thereby improving power efficiency in the D-ET mode.

[0150] (Variant of embodiment 1) The switched-capacitor circuit 20 of embodiment 1 includes a switch S224 for disconnecting the flying capacitors C200 and C202 from each other, and a switch S225 for disconnecting the flying capacitors C201 and C203 from each other, but may also include a switch for disconnecting the other two flying capacitors from each other.

[0151] For example, the switched-capacitor circuit 20B according to this modification may include a switch S230 for disconnecting the flying capacitors C202 and C204, and a switch S231 for disconnecting the flying capacitors C203 and C205, as shown in Fig. 9. Here, the switches S230 and S231 are examples of the 19th switch and the 20th switch, respectively.

[0152] In this case, the switched capacitor circuit 20B can realize a third mode that generates four discrete voltages V3, V4, V5, and V6 in addition to the first and second modes described above.

[0153] In the first phase of the third mode, a fifth set of switches S208, S211, S212, S215, S216, S219, S220, and S223 are closed, and a sixth set of switches S209, S210, S213, S214, S217, S218, S221, and S222 are open. Additionally, switches S200, S201, S202, S203, S204, S205, S206, and S207 are closed, and switches S224, S225, S230, and S231 are open.

[0154] In the second phase of the third mode, a fifth set of switches S208, S211, S212, S215, S216, S219, S220, and S223 are open, and a sixth set of switches S209, S210, S213, S214, S217, S218, S221, and S222 are closed. Additionally, switches S200, S201, S202, S203, S204, S205, S206, and S207 are closed, and switches S224, S225, S230, and S231 are open.

[0155] Thus, in the third mode, the fifth and sixth sets of switches alternate between open and closed during the first and second phases, while switches S200, S201, S202, S203, S204, S205, S206, and S207 remain closed during the first and second phases, and switches S224, S225, S230, and S231 remain open during the first and second phases.

[0156] As a result, the switched capacitor circuit 20B can maintain a plurality of discrete voltages V3, V4, V5, and V6 at four nodes N3, N4, N5, and N6 labeled V3, V4, V5, and V6, which satisfy the relationship (V6-V5):(V5-V4):(V4-V3):(V3-VG)=1:1:1:1. For example, when the regulated voltage Vcnv supplied from the pre-regulator circuit 10 is 5 V, the switched capacitor circuit 20B can generate four discrete voltages (V3, V4, V5, V6) of 1.67 V, 3.33 V, 5 V, and 6.67 V in the third mode.

[0157] Furthermore, as shown in FIG. 9, the switched capacitor circuit 20B may include a switch S232 for disconnecting the flying capacitors C204 and C206 from each other, and a switch S233 for disconnecting the flying capacitors C205 and C207 from each other.

[0158] In this case, the switched capacitor circuit 20B can realize a fourth mode that generates three discrete voltages V4, V5, and V6 in addition to the first, second, and third modes described above.

[0159] In the first phase of the fourth mode, a seventh set of switches S212, S215, S216, S219, S220, and S223 are closed, an eighth set of switches S213, S214, S217, S218, S221, and S222 are open, and switches S200, S201, S202, S203, S204, S205, S206, S207, S208, S209, S210, and S211 are closed, and switches S224, S225, S230, S231, S232, and S233 are open.

[0160] In the second phase of the fourth mode, a seventh set of switches S212, S215, S216, S219, S220, and S223 are open, an eighth set of switches S213, S214, S217, S218, S221, and S222 are closed, and switches S200, S201, S202, S203, S204, S205, S206, S207, S208, S209, S210, and S211 are closed, and switches S224, S225, S230, S231, S232, and S233 are open.

[0161] Thus, in the fourth mode, the seventh and eighth sets of switches alternate between open and closed during the first and second phases, while switches S200, S201, S202, S203, S204, S205, S206, S207, S208, S209, S210, and S211 remain closed during the first and second phases, and switches S224, S225, S230, S231, S232, and S233 remain open during the first and second phases.

[0162] This allows the switched capacitor circuit 20B to maintain a plurality of discrete voltages V4, V5, and V6 at three nodes N4, N5, and N6 labeled V4, V5, and V6, which satisfy the relationship (V6-V5):(V5-V4):(V4-VG)=1:1:1. For example, when the regulated voltage Vcnv supplied from the pre-regulator circuit 10 is 5 V, the switched capacitor circuit 20B can generate three discrete voltages (V4, V5, V6) of 2.5 V, 5 V, and 7.5 V in the fourth mode.

[0163] Furthermore, as shown in FIG. 9, the switched capacitor circuit 20B may include a switch S234 for disconnecting the flying capacitors C206 and C208 from each other, and a switch S235 for disconnecting the flying capacitors C207 and C209 from each other.

[0164] In this case, the switched capacitor circuit 20B can realize a fifth mode that generates two discrete voltages V5 and V6, in addition to the first, second, third, and fourth modes described above.

[0165] In the first phase of the fifth mode, a ninth set of switches S216, S219, S220, and S223 are closed, a tenth set of switches S217, S218, S221, and S222 are open, and switches S200, S201, S202, S203, S204, S205, S206, S207, S208, S209, S210, S211, S212, S213, S214, and S215 are closed, and switches S224, S225, S230, S231, S232, S233, S234, and S235 are open.

[0166] In the second phase of the fifth mode, a ninth set of switches S216, S219, S220, and S223 are open, a tenth set of switches S217, S218, S221, and S222 are closed, and switches S200, S201, S202, S203, S204, S205, S206, S207, S208, S209, S210, S211, S212, S213, S214, and S215 are closed, and switches S224, S225, S230, S231, S232, S233, S234, and S235 are open.

[0167] Thus, in the fifth mode, the ninth set of switches and the tenth set of switches alternate between open and closed during the first and second phases, while switches S200, S201, S202, S203, S204, S205, S206, S207, S208, S209, S210, S211, S212, S213, S214, and S215 remain closed during the first and second phases, and switches S224, S225, S230, S231, S232, S233, S234, and S235 remain open during the first and second phases.

[0168] This allows the switched capacitor circuit 20B to maintain multiple discrete voltages V5 and V6 that satisfy (V6-V5):(V5-VG)=1:1 at two nodes N5 and N6 labeled V5 and V6. For example, if the regulated voltage Vcnv supplied from the pre-regulator circuit 10 is 5 V, the switched capacitor circuit 20B can generate two discrete voltages (V5, V6) of (5 V, 10 V) in the fifth mode.

[0169] As described above, in the tracker circuit 1 according to this modification, the switched capacitor circuit 20B further includes flying capacitors C204 and C205, a smoothing capacitor C212, and switches S212, S213, S214, S215, S230, and S231. One end of the switch S208 and one end of the switch S209 are switchably connected to the other of the two electrodes of the flying capacitor C202 via the switch S230 and are connected to one of the two electrodes of the flying capacitor C204. One end of the switch S210 and one end of the switch S211 are switchably connected to the other of the two electrodes of the flying capacitor C203 via the switch S231 and are connected to one of the two electrodes of the flying capacitor C205. One end of the switch S212 and one end of the switch S213 are switchably connected to the other of the two electrodes of the flying capacitor C204. one end of the switch S214 and one end of the switch S215 are connected to the other of the two electrodes of the flying capacitor C205; the other end of the switch S209, the other end of the switch S211, the other end of the switch S212 and the other end of the switch S214 are connected to the other of the two electrodes of the smoothing capacitor C212 and one of the two electrodes of the smoothing capacitor C213; the other end of the switch S213 and the other end of the switch S215 are connected to the other of the two electrodes of the smoothing capacitor C213; one end of the switch S230 is connected to the other of the two electrodes of the flying capacitor C202; the other end of the switch S230 is connected to one of the two electrodes of the flying capacitor C204; one end of the switch S231 is connected to the other of the two electrodes of the flying capacitor C203 and the other end of the switch S231 is connected to one of the two electrodes of the flying capacitor C205.

[0170] According to this, the connection between the flying capacitors C202 and C204 can be disconnected by the switch S230, and the connection between the flying capacitors C203 and C205 can be disconnected by the switch S231. Therefore, it is possible to switch between enabling and disabling the flying capacitors C202 and C203 in the switched capacitor circuit 20B. As a result, it is possible to further increase the number of variations in the number of discrete voltages that can be generated by the switched capacitor circuit 20B. This makes it possible to generate multiple discrete voltages that are more suitable for the high-frequency signal amplified by the power amplifier 2, thereby further improving power efficiency in the D-ET mode.

[0171] Second Embodiment Next, a second embodiment will be described. In this embodiment, the main difference from the first embodiment is the circuit configuration of the switched-capacitor circuit. The following describes the second embodiment, focusing on the differences from the first embodiment, with reference to the drawings.

[0172] [2.1 Circuit Configuration of Communication Device 7A and Tracker Circuit 1A] First, the circuit configuration of the communication device 7A according to this embodiment will be described with reference to Fig. 10. Fig. 10 is a circuit configuration diagram of the communication device 7A according to this embodiment.

[0173] 10 is an exemplary circuit configuration, and the communication device 7A may be implemented using any of a wide variety of circuit implementations and circuit technologies, and therefore the description of the communication device 7A provided below should not be construed as limiting.

[0174] The communication device 7A is similar to the tracker circuit 1 according to the first embodiment, except that it includes a tracker circuit 1A instead of the tracker circuit 1. Therefore, a description of the communication device 7A will be omitted, except for the description of the tracker circuit 1A.

[0175] The tracker circuit 1A can supply the power supply voltage Vcc to the power amplifier 2 in the D-ET mode. Furthermore, the tracker circuit 1A may supply the power supply voltage Vcc to the power amplifier 2 in the APT mode. As shown in FIG. 2 , the tracker circuit 1A includes a pre-regulator circuit 10, a switched-capacitor circuit 20A, a power supply modulation circuit 30, an input terminal 41, an output terminal 42, and a digital control circuit 60.

[0176] That is, the tracker circuit 1A is similar to the tracker circuit 1 according to the first embodiment, except that it includes a switched-capacitor circuit 20A instead of the switched-capacitor circuit 20. Therefore, the description of the tracker circuit 1A will be omitted, except for the description of the switched-capacitor circuit 20A.

[0177] The switched-capacitor circuit 20A can generate a plurality of discrete voltages V1, V2, V3, V4, V5, and V6 or V1, V3, V4, V5, and V6 based on the regulated voltage Vcnv supplied by the pre-regulator circuit 10. Specifically, the switched-capacitor circuit 20A has a first mode in which the plurality of discrete voltages V1, V2, V3, V4, V5, and V6 (an example of a plurality of first discrete voltages) are generated from the regulated voltage Vcnv, and a second mode in which the plurality of discrete voltages V1, V3, V4, V5, and V6 (an example of a plurality of second discrete voltages) are generated from the regulated voltage Vcnv. In this case, the number of the plurality of discrete voltages V1, V2, V3, V4, V5, and V6 generated in the first mode is greater than the number of the plurality of discrete voltages V1, V3, V4, V5, and V6 generated in the second mode. The detailed circuit configuration of the switched-capacitor circuit 20A will be described later with reference to FIG.

[0178] [2.2 Circuit Configuration of Switched-Capacitor Circuit 20A] The circuit configuration of the switched-capacitor circuit 20A will be described with reference to Fig. 11. Fig. 11 is a circuit configuration diagram of the switched-capacitor circuit 20A according to this embodiment.

[0179] 11 is an example circuit configuration, and the switched capacitor circuit 20A may be implemented using any of a wide variety of circuit implementations and circuit techniques, and therefore the description of the switched capacitor circuit 20A provided below should not be construed as limiting.

[0180] The switched-capacitor circuit 20A has a ladder-type circuit configuration and can generate a plurality of discrete voltages V1, V2, V3, V4, V5, and V6 or V1, V3, V4, V5, and V6. Specifically, the switched-capacitor circuit 20A includes flying capacitors C200 to C209, smoothing capacitors C210 to C215, switches S200 to S223 and S226 to S228, an input terminal T200, and output terminals T201 to T206. Energy and charge are input from the pre-regulator circuit 10 to a node N5 via the input terminal T200 and are extracted from nodes N1, N2, N3, N4, N5, and N6 to a power supply modulation circuit 30 via output terminals T201, T202, T203, T204, T205, and T206.

[0181] In this embodiment, flying capacitors C202, C203, C204, and C205 are examples of a first flying capacitor, a second flying capacitor, a third flying capacitor, and a fourth flying capacitor, respectively. Furthermore, smoothing capacitors C211, C212, and C213 are examples of a first smoothing capacitor, a second smoothing capacitor, and a third smoothing capacitor, respectively. Furthermore, switches S204, S205, S206, S207, S208, S209, S210, S211, S212, S213, S214, and S215 are examples of a first switch, a second switch, a third switch, a fourth switch, a fifth switch, a sixth switch, a seventh switch, an eighth switch, a ninth switch, a tenth switch, an eleventh switch, and a twelfth switch, respectively.

[0182] The switch S226 is an example of a thirteenth switch, and is connected between the two electrodes of the smoothing capacitor C212. Specifically, one end of the switch S226 is connected to one of the two electrodes of the smoothing capacitor C212. Meanwhile, the other end of the switch S226 is connected to the other of the two electrodes of the smoothing capacitor C212. When the switch S226 is closed, the two electrodes of the smoothing capacitor C212 are short-circuited.

[0183] The switch S227 is an example of a fourteenth switch and is connected between the two electrodes of the flying capacitor C202. Specifically, one end of the switch S227 is connected to one of the two electrodes of the flying capacitor C202. Meanwhile, the other end of the switch S227 is connected to the other of the two electrodes of the flying capacitor C202. When the switch S227 is closed, the two electrodes of the flying capacitor C202 are short-circuited. Note that the switch S227 is optional and does not need to be included in the switched-capacitor circuit 20A.

[0184] The switch S228 is an example of a fifteenth switch and is connected between the two electrodes of the flying capacitor C203. Specifically, one end of the switch S228 is connected to one of the two electrodes of the flying capacitor C203. Meanwhile, the other end of the switch S228 is connected to the other of the two electrodes of the flying capacitor C203. When the switch S228 is closed, the two electrodes of the flying capacitor C203 are short-circuited. Note that the switch S228 is optional and does not need to be included in the switched-capacitor circuit 20A.

[0185] [2.3 Control Method of the Switched-Capacitor Circuit 20A] Next, a control method of the switched-capacitor circuit 20A according to this embodiment will be described with reference to FIGS. 12A, 12B, 13A, and 13B.

[0186] [2.3.1 First Mode] First, the first mode will be described with reference to Fig. 12A and Fig. 12B. Fig. 12A is a circuit diagram showing a connection state in the first phase of the first mode of the switched-capacitor circuit 20A according to this embodiment. Fig. 12B is a circuit diagram showing a connection state in the second phase of the first mode of the switched-capacitor circuit 20A according to this embodiment.

[0187] The first mode is a mode in which the switched capacitor circuit 20A generates six discrete voltages V1, V2, V3, V4, V5, and V6, i.e., in the first mode, the switched capacitor circuit 20A forms six stages of switched capacitors.

[0188] In the first mode, the first and second phases are alternately repeated based on a control signal CS20 from the digital control circuit 60.

[0189] In the first phase of the first mode, as shown in Figure 12A, a first set of switches S200, S203, S204, S207, S208, S211, S212, S215, S216, S219, S220, and S223 are closed, and a second set of switches S201, S202, S205, S206, S209, S210, S213, S214, S217, S218, S221, and S222 are open. Additionally, switches S226, S227, and S228 are open.

[0190] In the second phase of the first mode, as shown in Figure 12B, a first set of switches S200, S203, S204, S207, S208, S211, S212, S215, S216, S219, S220, and S223 are open, and a second set of switches S201, S202, S205, S206, S209, S210, S213, S214, S217, S218, S221, and S222 are closed. Additionally, switches S226, S227, and S228 are open.

[0191] Thus, in the first mode, the first set of switches and the second set of switches alternate between open and closed during the first and second phases, while switches S226, S227, and S228 remain open during the first and second phases.

[0192] By repeating the first and second phases, the flying capacitors C200, C201, C202, C203, C204, C205, C206, C207, C208, and C209 can be charged and discharged in a complementary manner. For example, in one of the first and second phases, the flying capacitors C200, C202, C204, C206, and C208 charge the smoothing capacitors C210, C211, C212, C213, C214, and C215, and in the other of the first and second phases, the flying capacitors C201, C203, C205, C207, and C209 charge the smoothing capacitors C210, C211, C212, C213, C214, and C215. In other words, smoothing capacitors C210, C211, C212, C213, C214, and C215 are always charged from any of flying capacitors C200, C201, C202, C203, C204, C205, C206, C207, C208, and C209, so even if a current flows from any of nodes N1, N2, N3, N4, N5, and N6 to power supply modulation circuit 30 at high speed, charge is replenished at high speed to any of nodes N1, N2, N3, N4, N5, and N6, and fluctuations in the potential of nodes N1, N2, N3, N4, N5, and N6 can be suppressed.

[0193] By operating in this manner, the switched-capacitor circuit 20A can maintain approximately equal voltages across each of the smoothing capacitors C210, C211, C212, C213, C214, and C215. Specifically, at six nodes N1, N2, N3, N4, N5, and N6 labeled V1, V2, V3, V4, V5, and V6, a plurality of discrete voltages V1, V2, V3, V4, V5, and V6 are maintained that satisfy the following relationship: (V6-V5):(V5-V4):(V4-V3):(V3-V2):(V2-V1):(V1-VG)=1:1:1:1:1:1:1. For example, if the regulated voltage Vcnv supplied from the pre-regulator circuit 10 is 5V, the switched capacitor circuit 20A can generate six discrete voltages (V1, V2, V3, V4, V5, V6) (1V, 2V, 3V, 4V, 5V, 6V).

[0194] [2.3.2 Second Mode] Next, the second mode will be described with reference to Fig. 13A and Fig. 13B. Fig. 13A is a circuit diagram showing a connection state in the first phase of the second mode of the switched-capacitor circuit 20A according to this embodiment. Fig. 13B is a circuit diagram showing a connection state in the second phase of the second mode of the switched-capacitor circuit 20A according to this embodiment.

[0195] The second mode is a mode in which the switched capacitor circuit 20A generates five discrete voltages V1, V3, V4, V5, and V6, i.e., in the second mode, the switched capacitor circuit 20A forms a five-stage switched capacitor.

[0196] In the second mode, the first and second phases are alternately repeated based on a control signal CS20 from the digital control circuit 60.

[0197] In the first phase of the second mode, as shown in Figure 13A, a third set of switches S200, S203, S204, S207, S212, S215, S216, S219, S220, and S223 are closed, and a fourth set of switches S201, S202, S205, S206, S213, S214, S217, S218, S221, and S222 are open. Additionally, switches S208, S209, S210, and S211 are open, and switches S226, S227, and S228 are closed.

[0198] In the second phase of the second mode, as shown in Figure 13B, a third set of switches S200, S203, S204, S207, S212, S215, S216, S219, S220, and S223 are open, and a fourth set of switches S201, S202, S205, S206, S213, S214, S217, S218, S221, and S222 are closed. Additionally, switches S208, S209, S210, and S211 are open, and switches S226, S227, and S228 are closed.

[0199] Thus, in the second mode, the third set of switches and the fourth set of switches alternate between open and closed during the first and second phases, while switches S208, S209, S210, and S211 remain open during the first and second phases, and switches S226, S227, and S228 remain closed during the first and second phases.

[0200] By repeating the first and second phases, the flying capacitors C200, C201, C204, C205, C206, C207, C208, and C209 can be charged and discharged in a complementary manner. For example, in one of the first and second phases, the flying capacitors C200, C204, C206, and C208 charge the smoothing capacitors C210, C211, C213, C214, and C215, and in the other of the first and second phases, the flying capacitors C201, C205, C207, and C209 charge the smoothing capacitors C210, C211, C213, C214, and C215. In other words, smoothing capacitors C210, C211, C213, C214, and C215 are always charged from one of flying capacitors C200, C201, C204, C205, C206, C207, C208, and C209, so even if a current flows from one of nodes N1, N3, N4, N5, and N6 to power supply modulation circuit 30 at high speed, charge is replenished at high speed to one of nodes N1, N3, N4, N5, and N6, and fluctuations in the potential of nodes N1, N3, N4, N5, and N6 can be suppressed.

[0201] By operating in this manner, the switched-capacitor circuit 20A can maintain approximately equal voltages across each of the smoothing capacitors C210, C211, C213, C214, and C215. Specifically, at five nodes N1, N3, N4, N5, and N6 labeled V1, V3, V4, V5, and V6, a plurality of discrete voltages V1, V3 (=V2), V4, V5, and V6 that satisfy the following relationship: (V6-V5):(V5-V4):(V4-V3):(V3-V1):(V1-VG)=1:1:1:1:1. For example, if the regulated voltage Vcnv supplied from the pre-regulator circuit 10 is 5 V, the switched capacitor circuit 20A can generate five discrete voltages (V1, V3, V4, V5, V6) (1.25 V, 2.5 V, 3.75 V, 5 V, 6.25 V).

[0202] [2.4 Multiple Discrete Voltages Generated in First Mode and Second Mode] Next, multiple discrete voltages generated by the switched-capacitor circuit 20A according to this embodiment will be described with reference to Fig. 14. Fig. 14 is a diagram showing an example of multiple discrete voltages generated by the switched-capacitor circuit 20A according to this embodiment. In Fig. 14, the power supply voltage Vcc corresponding to the peak power of the high-frequency signal amplified by the power amplifier 2 is 6 V.

[0203] For example, in the first mode, the pre-regulator circuit 10 supplies a regulated voltage Vcnv of 5 V to the switched capacitor circuit 20A, which can generate six discrete voltages (1 V, 2 V, 3 V, 4 V, 5 V, and 6 V).

[0204] For example, in the second mode, the pre-regulator circuit 10 supplies a regulated voltage Vcnv of 4.8 V to the switched capacitor circuit 20A, which can generate five discrete voltages (1.2 V, 2.4 V, 3.6 V, 4.8 V, and 6 V).

[0205] In this embodiment, as in the first embodiment, the second mode is applied to the switched-capacitor circuit 20A when the PAPR of the high-frequency signal is equal to or greater than a threshold, and the first mode is applied to the switched-capacitor circuit 20A when the PAPR of the high-frequency signal is less than the threshold, thereby improving power efficiency.

[0206] [2.5 Summary] As described above, the tracker circuit 1A according to this embodiment includes a switched-capacitor circuit 20A configured to generate a plurality of discrete voltages from an input voltage, and a power supply modulation circuit 30 configured to selectively output at least one of the generated discrete voltages to the power amplifier 2. The switched-capacitor circuit 20A includes flying capacitors C202, C203, C204, and C205, smoothing capacitors C211, C212, and C213, and switches S204, S205, S206, S207, S208, S209, S210, S211, S212, and S213. One end of the switch S204 and one end of the switch S205 are connected to one of the two electrodes of the flying capacitor C202, one end of the switch S206 and one end of the switch S207 are connected to one of the two electrodes of the flying capacitor C203, one end of the switch S208 and one end of the switch S209 are connected to the other of the two electrodes of the flying capacitor C202 and one of the two electrodes of the flying capacitor C204, and one end of the switch S210 and one end of the switch S211 are connected to the flying capacitor C205. One end of the switch S212 and one end of the switch S213 are connected to the other of the two electrodes of the flying capacitor C204, one end of the switch S214 and one end of the switch S215 are connected to the other of the two electrodes of the flying capacitor C205, the other end of the switch S204, the other end of the switch S206 and one of the two electrodes of the smoothing capacitor C211 are connected to each other, and the other end of the switch S205, the other end of the switch S207 and the switch S218 are connected to each other. The other end of switch S208 and the other end of switch S210 are connected to the other of the two electrodes of smoothing capacitor C211 and one of the two electrodes of smoothing capacitor C212, the other end of switch S209, the other end of switch S211, the other end of switch S212 and the other end of switch S214 are connected to the other of the two electrodes of smoothing capacitor C212 and one of the two electrodes of smoothing capacitor C213, the other end of switch S213 and the other end of switch S215 are connected to the other of the two electrodes of smoothing capacitor C213, and one end and the other end of switch S226 are connected to the smoothing capacitor C211,C212 and C213 are connected to one and the other of the two electrodes, respectively.

[0207] This allows the smoothing capacitor C211, C212, or C213 to be short-circuited by the switch S226. Therefore, it is possible to switch between enabling and disabling the smoothing capacitor C211, C212, or C213 in the switched capacitor circuit 20A. As a result, it is possible to increase the number of variations in the number of discrete voltages that can be generated by the switched capacitor circuit 20A. This makes it possible to generate multiple discrete voltages that are more suitable for the high-frequency signal amplified by the power amplifier 2, thereby improving power efficiency in D-ET mode.

[0208] Also, for example, in the tracker circuit 1A according to this embodiment, one end and the other end of the switch S226 may be connected to one and the other of the two electrodes of the smoothing capacitor C212, respectively, and when the PAPR of the high-frequency signal amplified by the power amplifier 2 is less than a threshold, the switch S226 may be kept open, and when the PAPR is equal to or greater than the threshold, the switches S208, S209, S210 and S211 may be kept open and the switch S226 may be kept closed.

[0209] This allows the number of discrete voltages to be reduced when the PAPR of the high frequency signal amplified by the power amplifier 2 is large. For the same peak power of the high frequency signal, the average power of a high frequency signal with a larger PAPR will be lower than the average power of a high frequency signal with a smaller PAPR. As shown in FIG. 7 , when the number of voltages that can be supplied in the D-ET mode is limited, a smaller number of discrete voltages allows the envelope signal of the high frequency signal to be tracked down to a lower voltage. Therefore, when the PAPR of the high frequency signal amplified by the power amplifier 2 is large, reducing the number of discrete voltages can improve power efficiency in the D-ET mode.

[0210] For example, in the tracker circuit 1A according to this embodiment, the switched capacitor circuit 20A may further include a switch S227 and a switch S228, and one end and the other end of the switch S226 may be connected to one and the other of the two electrodes of the smoothing capacitor C212, one end and the other end of the switch S227 may be connected to one and the other of the two electrodes of the flying capacitor C202, and one end and the other end of the switch S228 may be connected to one and the other of the two electrodes of the flying capacitor C203, respectively.

[0211] According to this, the flying capacitor C202 can be short-circuited by the switch S227, and the flying capacitor C203 can be short-circuited by the switch S228. Therefore, by closing the switches S227 and S228 when the switch S226 is closed, the series connection between the flying capacitor C204 and the flying capacitor C202 can be released, and the series connection between the flying capacitor C205 and the flying capacitor C203 can be released. As a result, the decrease in the capacitance of the flying capacitors can be suppressed, and fluctuations in the voltage supplied by the switched-capacitor circuit 20A can be suppressed.

[0212] Also, for example, in the tracker circuit 1A according to this embodiment, when the PAPR of the high frequency signal amplified by the power amplifier 2 is less than a threshold, the switches S226, S227, and S228 may be kept open, and when the PAPR is equal to or greater than the threshold, the switches S208, S209, S210, and S211 may be kept open, and the switches S226, S227, and S228 may be kept closed.

[0213] This allows the number of discrete voltages to be reduced when the PAPR of the high frequency signal amplified by the power amplifier 2 is large. For the same peak power of the high frequency signal, the average power of a high frequency signal with a larger PAPR will be lower than the average power of a high frequency signal with a smaller PAPR. As shown in FIG. 7 , when the number of voltages that can be supplied in the D-ET mode is limited, a smaller number of discrete voltages allows the envelope signal of the high frequency signal to be tracked down to a lower voltage. Therefore, when the PAPR of the high frequency signal amplified by the power amplifier 2 is large, reducing the number of discrete voltages can improve power efficiency in the D-ET mode.

[0214] In addition, the tracker circuit 1A of this embodiment includes a switched capacitor circuit 20A having a first mode for generating a plurality of first discrete voltages from an input voltage and a second mode for generating a plurality of second discrete voltages from the input voltage, and a power supply modulation circuit 30 configured to selectively output at least one of the generated plurality of first discrete voltages or the plurality of second discrete voltages to the power amplifier 2, wherein the number of the plurality of first discrete voltages is greater than the number of the plurality of second discrete voltages.

[0215] This allows the number of discrete voltages generated by the switched capacitor circuit 20A to be switched, thereby enabling the generation of discrete voltages that are more suitable for the high frequency signal amplified by the power amplifier 2, thereby improving power efficiency in the D-ET mode.

[0216] (Variation of Embodiment 2) The switched-capacitor circuit 20A according to embodiment 2 includes the switch S226 for short-circuiting the smoothing capacitor C212. However, instead of or in addition to the switch S226, the switched-capacitor circuit 20A may include a switch for short-circuiting each of the smoothing capacitors C210, C211, C213, C214, or C215, or any combination thereof.

[0217] For example, the switched capacitor circuit 20C according to this modification may include a switch S242 for short-circuiting the smoothing capacitor C213, as shown in FIG. 15, and may further include switches S247 and S248 for short-circuiting the flying capacitors C204 and C205, respectively.

[0218] The switch S242 is an example of a 16th switch, and is connected between two electrodes of the smoothing capacitor C213. Specifically, one end of the switch S242 is connected to one of the two electrodes of the smoothing capacitor C213. Meanwhile, the other end of the switch S242 is connected to the other of the two electrodes of the smoothing capacitor C213. When the switch S242 is closed, the two electrodes of the smoothing capacitor C213 are short-circuited.

[0219] The switch S247 is an example of a seventeenth switch and is connected between the two electrodes of the flying capacitor C204. Specifically, one end of the switch S247 is connected to one of the two electrodes of the flying capacitor C204. Meanwhile, the other end of the switch S247 is connected to the other of the two electrodes of the flying capacitor C204. When the switch S247 is closed, the two electrodes of the flying capacitor C204 are short-circuited. Note that the switch S247 is optional and does not need to be included in the switched-capacitor circuit 20C.

[0220] The switch S248 is an example of an 18th switch and is connected between the two electrodes of the flying capacitor C205. Specifically, one end of the switch S248 is connected to one of the two electrodes of the flying capacitor C205. Meanwhile, the other end of the switch S248 is connected to the other of the two electrodes of the flying capacitor C205. When the switch S248 is closed, the two electrodes of the flying capacitor C205 are short-circuited. Note that the switch S248 is optional and does not need to be included in the switched-capacitor circuit 20C.

[0221] In the second mode described above, for example, switches S212, S213, S214, and S215 may be maintained open during the first and second phases instead of switches S208, S209, S210, and S211, and switches S242, S247, and S248 may be maintained closed during the first and second phases instead of switches S226, S227, and S228. This allows the switched capacitor circuit 20C to generate five discrete voltages V1, V2, V4 (=V3), V5, and V6.

[0222] Furthermore, in addition to the first and second modes described above, the switched capacitor circuit 20C can also realize a third mode in which four discrete voltages V1, V4, V5, and V6 are generated, for example.

[0223] In the first phase of the third mode, for example, a fifth set of switches S200, S203, S204, S207, S216, S219, S220, and S223 are closed, a sixth set of switches S201, S202, S205, S206, S217, S218, S221, and S222 are open, switches S208, S209, S210, S211, S212, S213, S214, and S215 are open, and switches S226, S227, S228, S242, S247, and S248 are closed.

[0224] In the second phase of the third mode, for example, a fifth set of switches S200, S203, S204, S207, S216, S219, S220, and S223 are open, a sixth set of switches S201, S202, S205, S206, S217, S218, S221, and S222 are closed, and switches S208, S209, S210, S211, S212, S213, S214, and S215 are open, and switches S226, S227, S228, S242, S247, and S248 are closed.

[0225] Thus, in the third mode, the fifth and sixth sets of switches alternate between open and closed during the first and second phases, while switches S208, S209, S210, S211, S212, S213, S214, and S215 remain open during the first and second phases, and switches S226, S227, S228, S242, S247, and S248 remain closed during the first and second phases.

[0226] As a result, the switched capacitor circuit 20C can maintain a plurality of discrete voltages V1, V4 (=V3=V2), V5, and V6 at three nodes N1, N4, N5, and N6 labeled V1, V4, V5, and V6, which satisfy the relationship (V6-V5):(V5-V4):(V4-V1):(V1-VG)=1:1:1:1. For example, when the regulated voltage Vcnv supplied from the pre-regulator circuit 10 is 5 V, the switched capacitor circuit 20C can generate four discrete voltages (V1, V4, V5, V6) of 1.67 V, 3.33 V, 5 V, and 6.67 V in the third mode.

[0227] 15, the switched capacitor circuit 20C may include switches S240, S241, S243, S244, or any combination thereof, instead of or in addition to the switch S242. Similarly, the switched capacitor circuit 20C may include a set of switches S245 and S246, a set of switches S249 and S250, a set of switches S251 and S252, or any combination of any set thereof, instead of or in addition to the set of switches S247 and S248.

[0228] As described above, in the tracker circuit 1A according to this modified example, the switched capacitor circuit 20C further includes a switch S242, and one end and the other end of the switch S242 may be connected to one and the other of the two electrodes of the smoothing capacitor C213, respectively.

[0229] This allows the smoothing capacitor C213 to be short-circuited by the switch S242. Therefore, it is possible to switch between enabling and disabling the smoothing capacitor C213 in the switched capacitor circuit 20C. As a result, it is possible to increase the number of variations in the number of discrete voltages that can be generated by the switched capacitor circuit 20C. This makes it possible to generate a plurality of discrete voltages that are more suitable for the high-frequency signal amplified by the power amplifier 2, thereby improving power efficiency in the D-ET mode.

[0230] For example, in the tracker circuit 1A according to this modified example, the switched capacitor circuit 20C further includes switches S247 and S248, and one end and the other end of the switch S247 may be connected to one and the other of the two electrodes of the flying capacitor C204, respectively, and one end and the other end of the switch S248 may be connected to one and the other of the two electrodes of the flying capacitor C205, respectively.

[0231] This allows the flying capacitor C204 to be short-circuited by switch S247, and the flying capacitor C205 to be short-circuited by switch S248. Therefore, by closing switches S247 and S248 when switch S242 is closed, the series connection between flying capacitor C206 and flying capacitor C204 can be released, and the series connection between flying capacitor C207 and flying capacitor C205 can be released. As a result, it is possible to suppress a decrease in the capacitance of the flying capacitors, and to suppress fluctuations in the voltage supplied by switched-capacitor circuit 20C.

[0232] (Other Embodiments) The tracker circuit according to the present invention has been described above based on the embodiments, but the tracker circuit according to the present invention is not limited to the above embodiments. The present invention also includes other embodiments realized by combining any of the components in the above embodiments, modifications obtained by applying various modifications to the above embodiments that would occur to those skilled in the art without departing from the spirit of the present invention, and various devices incorporating the above tracker circuit.

[0233] For example, in the circuit configurations of the various circuits according to the above embodiments, other circuit elements and wiring may be inserted between the paths connecting the circuit elements and signal paths disclosed in the drawings. For example, an inductor and / or a capacitor may be inserted between the tracker circuit and the power amplifier.

[0234] In the switched-capacitor circuits according to the above embodiments, the connection relationship between the input terminals and the nodes may be changed. For example, in the first and / or second embodiments, the input terminal T200 may be connected to the node N1, N2, N3, N4, or N6 instead of the node N5. Even in this case, the same effects as those of the first and / or second embodiments can be obtained.

[0235] The tracker circuit according to each of the above embodiments may include a plurality of power supply modulation circuits, in which case the tracker circuit can supply different voltages to a plurality of power amplifiers.

[0236] Although the switched capacitor circuits according to the above embodiments have a circuit configuration capable of generating a maximum of six discrete voltages, they may have a circuit configuration capable of generating a maximum of three, four, five, or seven or more discrete voltages. For example, in the first embodiment, if the switched capacitor circuit 20 can generate a maximum of three discrete voltages, the switched capacitor circuit 20 does not need to include the flying capacitors C204 to C209, the smoothing capacitors C213 to C215, and the switches S212 to S223.

[0237] The present invention can be widely used in communication devices such as mobile phones as a tracker circuit that supplies voltage to a power amplifier.

[0238] 1, 1A Tracker circuit 2 Power amplifier 3 Filter 5 RFIC 6 Antenna 7, 7A Communication device 10 Pre-regulator circuit 20, 20A, 20B, 20C Switched capacitor circuit 30 Power supply modulation circuit 41, T101, T200, T301, T302, T303, T304, T305, T306 Input terminal 42, T102, T201, T202, T203, T204, T205, T206, T307 Output terminal 50 DC power supply 60 Digital control circuit 61 First controller 62 Second controller C101 Capacitor C200, C201, C202, C203, C204, C205, C206, C207, C208, C209 Flying capacitor C210, C211, C212, C213, C214, C215 Smoothing capacitors CS10, CS20, CS30 Control signal L101 Power inductor S101, S102, S103, S104, S200, S201, S202, S203, S204, S205, S206, S207, S208, S209, S210, S211, S212, S213, S214, S215, S216, S217, S218, S219, S220, S221, S222, S223, S224 , S225, S226, S227, S228, S230, S231, S232, S233, S234, S235, S240, S241, S242, S243, S244, S245, S246, S247, S248, S249, S250, S251, S252, S301, S302, S303, S304, S305, S306 Switch

Claims

1. A power supply modulation circuit comprising: a switched capacitor circuit configured to generate a plurality of discrete voltages from an input voltage; and a power supply modulation circuit configured to selectively output at least one of the generated discrete voltages to a power amplifier, wherein the switched capacitor circuit includes: a first flying capacitor, a second flying capacitor, a third flying capacitor and a fourth flying capacitor; a first smoothing capacitor, a second smoothing capacitor and a third smoothing capacitor; and a first switch, a second switch, a third switch, a fourth switch, a fifth switch, a sixth switch, a seventh switch, an eighth switch, a ninth switch, a tenth switch, an eleventh switch, a twelfth switch, a thirteenth switch and a fourteenth switch, wherein one end of the first switch and one end of the second switch are connected to one of two electrodes of the first flying capacitor, and one end of the third switch and one end of the fourth switch are connected to one of two electrodes of the second flying capacitor, one end of the fifth switch and one end of the sixth switch are switchably connected to the other of the two electrodes of the first flying capacitor via the thirteenth switch, and are connected to one of the two electrodes of the third flying capacitor; one end of the seventh switch and one end of the eighth switch are switchably connected to the other of the two electrodes of the second flying capacitor via the fourteenth switch, and are connected to one of the two electrodes of the fourth flying capacitor; one end of the ninth switch and one end of the tenth switch are connected to the other of the two electrodes of the third flying capacitor; one end of the eleventh switch and one end of the twelfth switch are connected to the other of the two electrodes of the fourth flying capacitor; the other end of the first switch, the other end of the third switch, and one of the two electrodes of the first smoothing capacitor are connected to ground; the other end of the second switch, the other end of the fourth switch, the other end of the fifth switch, and the other end of the seventh switch are connected to the other of the two electrodes of the first smoothing capacitor and one of the two electrodes of the second smoothing capacitor,a tracker circuit, wherein the other end of the sixth switch, the other end of the eighth switch, the other end of the ninth switch, and the other end of the eleventh switch are connected to the other of the two electrodes of the second smoothing capacitor and one of the two electrodes of the third smoothing capacitor; the other end of the tenth switch and the other end of the twelfth switch are connected to the other of the two electrodes of the third smoothing capacitor; one end of the thirteenth switch is connected to the other of the two electrodes of the first flying capacitor; the other end of the thirteenth switch is connected to one of the two electrodes of the third flying capacitor; one end of the fourteenth switch is connected to the other of the two electrodes of the second flying capacitor; and the other end of the fourteenth switch is connected to one of the two electrodes of the fourth flying capacitor.

2. The tracker circuit of claim 1, wherein when a PAPR (Peak to Average Power Ratio) of a high-frequency signal amplified by the power amplifier is less than a threshold, the thirteenth switch and the fourteenth switch are maintained closed, and when the PAPR is equal to or greater than the threshold, the first switch, the second switch, the third switch and the fourth switch are maintained closed, and the thirteenth switch and the fourteenth switch are maintained open.

3. The switched capacitor circuit further includes a fifth flying capacitor and a sixth flying capacitor, a fourth smoothing capacitor, a fifteenth switch, a sixteenth switch, a seventeenth switch, an eighteenth switch, a nineteenth switch, and a twentieth switch, one end of the ninth switch and one end of the tenth switch are switchably connected to the other of the two electrodes of the third flying capacitor via the nineteenth switch, and are connected to one of the two electrodes of the fifth flying capacitor, one end of the eleventh switch and one end of the twelfth switch are switchably connected to the other of the two electrodes of the fourth flying capacitor via the twentieth switch, and are connected to one of the two electrodes of the sixth flying capacitor, one end of the fifteenth switch and one end of the sixteenth switch are connected to the other of the two electrodes of the fifth flying capacitor, one end of the seventeenth switch and one end of the eighteenth switch are connected to the other of the two electrodes of the sixth flying capacitor, The tracker circuit of claim 1 or 2, wherein the other end of the 10th switch, the other end of the 12th switch, the other end of the 15th switch, and the other end of the 17th switch are connected to the other of the two electrodes of the third smoothing capacitor and one of the two electrodes of the fourth smoothing capacitor, the other end of the 16th switch and the other end of the 18th switch are connected to the other of the two electrodes of the fourth smoothing capacitor, one end of the 19th switch is connected to the other of the two electrodes of the third flying capacitor, the other end of the 19th switch is connected to one of the two electrodes of the fifth flying capacitor, one end of the 20th switch is connected to the other of the two electrodes of the fourth flying capacitor, and the other end of the 20th switch is connected to one of the two electrodes of the sixth flying capacitor.

4. A power supply modulation circuit comprising: a switched capacitor circuit configured to generate a plurality of discrete voltages from an input voltage; and a power supply modulation circuit configured to selectively output at least one of the generated discrete voltages to a power amplifier, wherein the switched capacitor circuit includes: a first flying capacitor, a second flying capacitor, a third flying capacitor and a fourth flying capacitor; a first smoothing capacitor, a second smoothing capacitor and a third smoothing capacitor; and a first switch, a second switch, a third switch, a fourth switch, a fifth switch, a sixth switch, a seventh switch, an eighth switch, a ninth switch, a tenth switch, an eleventh switch, a twelfth switch and a thirteenth switch, wherein one end of the first switch and one end of the second switch are connected to one of two electrodes of the first flying capacitor, and one end of the third switch and one end of the fourth switch are connected to one of two electrodes of the second flying capacitor, one end of the fifth switch and one end of the sixth switch are connected to the other of the two electrodes of the first flying capacitor and one of the two electrodes of the third flying capacitor; one end of the seventh switch and one end of the eighth switch are connected to the other of the two electrodes of the second flying capacitor and one of the two electrodes of the fourth flying capacitor; one end of the ninth switch and one end of the tenth switch are connected to the other of the two electrodes of the third flying capacitor; one end of the eleventh switch and one end of the twelfth switch are connected to the other of the two electrodes of the fourth flying capacitor; the other end of the first switch, the other end of the third switch and one of the two electrodes of the first smoothing capacitor are connected to each other; the other end of the second switch, the other end of the fourth switch, the other end of the fifth switch and the other end of the seventh switch are connected to the other of the two electrodes of the first smoothing capacitor and one of the two electrodes of the second smoothing capacitor; the other end of the sixth switch, the other end of the eighth switch, the other end of the ninth switch, and the other end of the eleventh switch are connected to the other of the two electrodes of the second smoothing capacitor and one of the two electrodes of the third smoothing capacitor,A tracker circuit, wherein the other end of the tenth switch and the other end of the twelfth switch are connected to the other of the two electrodes of the third smoothing capacitor, and one end and the other end of the thirteenth switch are connected to one and the other of the two electrodes of the first smoothing capacitor, the second smoothing capacitor, or the third smoothing capacitor, respectively.

5. The tracker circuit of claim 4, wherein one end and the other end of the 13th switch are connected to one and the other of the two electrodes of the second smoothing capacitor, respectively; when the PAPR of the high-frequency signal amplified by the power amplifier is less than a threshold, the 13th switch is maintained open; and when the PAPR is equal to or greater than the threshold, the fifth switch, the sixth switch, the seventh switch and the eighth switch are maintained open and the 13th switch is maintained closed.

6. The tracker circuit of claim 4, wherein the switched capacitor circuit further includes a fourteenth switch and a fifteenth switch, one end and the other end of the thirteenth switch being connected to one and the other of the two electrodes of the second smoothing capacitor, one end and the other end of the fourteenth switch being connected to one and the other of the two electrodes of the first flying capacitor, one end and the other end of the fifteenth switch being connected to one and the other of the two electrodes of the second flying capacitor, respectively.

7. The tracker circuit of claim 6, wherein when a PAPR of a high-frequency signal amplified by the power amplifier is less than a threshold, the thirteenth switch, the fourteenth switch, and the fifteenth switch are maintained open, and when the PAPR is equal to or greater than the threshold, the fifth switch, the sixth switch, the seventh switch, and the eighth switch are maintained open, and the thirteenth switch, the fourteenth switch, and the fifteenth switch are maintained closed.

8. The tracker circuit of claim 4, wherein the switched capacitor circuit further includes a 16th switch, one end and the other end of the 13th switch are connected to one and the other of two electrodes of the second smoothing capacitor, respectively, and one end and the other end of the 16th switch are connected to one and the other of two electrodes of the third smoothing capacitor, respectively.

9. The tracker circuit of claim 8, wherein the switched capacitor circuit further includes a fourteenth switch and a fifteenth switch, one end and the other end of the fourteenth switch being connected to one and the other of the two electrodes of the first flying capacitor, respectively, and one end and the other end of the fifteenth switch being connected to one and the other of the two electrodes of the second flying capacitor, respectively.

10. The tracker circuit of claim 8 or 9, wherein the switched capacitor circuit further includes a 17th switch and an 18th switch, one end and the other end of the 17th switch being connected to one and the other of the two electrodes of the third flying capacitor, respectively, and one end and the other end of the 18th switch being connected to one and the other of the two electrodes of the fourth flying capacitor, respectively.

11. A tracker circuit comprising: a switched capacitor circuit having a first mode for generating a plurality of first discrete voltages from an input voltage and a second mode for generating a plurality of second discrete voltages from the input voltage; and a power supply modulation circuit configured to selectively output at least one of the generated plurality of first discrete voltages or the plurality of second discrete voltages to a power amplifier, wherein the number of the plurality of first discrete voltages is greater than the number of the plurality of second discrete voltages.

Images