Envelope Tracking Method and Device

Abstract

The present disclosure provides an envelope tracking method and apparatus, which includes the steps of: using a boost circuit (303) to obtain a target envelope tracking input current signal (IA); and transmitting the target envelope tracking input current signal (IA) to an amplifier circuit via the boost circuit (303), the amplifier circuit including an operational amplifier (301) and a feedback network (302), the operational amplifier (301) operating to a floating ground; and the amplifier circuit performing closed-loop conversion amplification on the target envelope tracking input current signal (IA) to output an envelope tracking output voltage (VOUT). The related envelope tracking apparatus solves the problem in the related art that when the envelope tracking output voltage (VOUT) has a high amplitude and a large swing, the operational amplifier (301) experiences high losses and low efficiency during linear amplification. This achieves more effective conversion amplification of the target envelope tracking input current signal (IA), improving the conversion efficiency of the operational amplifier (301) during amplification, reducing amplification losses, and improving user experience.

Description

Technical Field

[0001] Examples of the present disclosure relate to the technical field of electronic devices, but are not limited thereto. Specifically, they relate to, but are not limited to, envelope tracking methods and devices.

Background Art

[0002] Envelope tracking technology is applied in various fields such as communication. The output of the envelope tracking power supply changes along with the required signal changes, has a high bandwidth, generally in the range of several megahertz to several hundred megahertz, and is applied to an envelope tracking power amplifier circuit to supply power to the power amplifier so that the power supply voltage of the power amplifier changes along with the power of the signal that requires amplification, thereby improving the efficiency of the power amplifier.

[0003] Conventional technologies generally perform amplification tracking on the input envelope signal by using a first-stage operational amplifier as shown in FIG. 1 or by using a two-stage operational amplifier as shown in FIG. 2.

[0004] As shown in FIG. 1, the circuit of the first-stage amplifier used is simple and has low power consumption. However, when the amplitude value of the output voltage is large, in order to improve the bandwidth of the envelope signal tracking, the gain of the operational amplifier must not be increased, so the amplitude value of the input envelope signal Ui must be large, which is generally difficult to achieve.

[0005] In FIG. 2, when using a two-stage amplifier, the amplitude value of the input envelope signal can be small, so it is easy to implement. However, because a first-stage operational amplifier is added, the number of components increases, the power consumption becomes large, the time delay of the signal increases, and it also affects the efficiency.

Summary of the Invention

Problems to be Solved by the Invention

[0006] The required power supply envelope voltage range of the envelope tracking power amplifier is wide. For example, when it is 10~30V, the output voltage range of the envelope tracking power supply should also be correspondingly wide and should be within the range of 10~30V. When using the above conventional circuits for amplification tracking, since the output voltage range of the operational amplifier is wide, the power supply voltage must also be 30V or more. The swing of the output voltage is large, the amplitude value and frequency are high. If the circuit in FIG. 1 is used, the amplitude value of the required input envelope signal Ui becomes large and it is difficult to realize. If the circuit in FIG. 2 is used, there are many components, the loss of the operational amplifier is large, which affects the efficiency. Although the efficiency of the power amplifier is improved, the efficiency of the envelope tracking power supply in the power supply part decreases, which affects the overall efficiency. As can be seen from this, in the related art, when the amplitude of the output voltage of envelope tracking is large, in the linear amplification process, the loss of the operational amplifier is large and the efficiency is low.

[0007] In order to solve the technical problem that in the related art, when the amplitude of the output voltage of envelope tracking is large, in the linear amplification process, the loss of the operational amplifier is large and the efficiency is low, the embodiments of the present disclosure provide an envelope tracking method and apparatus.

Means for Solving the Problem

[0008] In order to solve the above technical problem, the embodiments of the present disclosure provide an envelope tracking apparatus, the envelope tracking apparatus includes an amplification circuit and a boost circuit, the amplification circuit includes an operational amplifier and a feedback network, The operational amplifier includes a non-inverting input terminal, a power supply minus terminal, a power supply plus terminal, an output terminal of the operational amplifier and an inverting input terminal. A reference voltage VREF is applied to the non-inverting input terminal. The power supply minus terminal is connected to a first voltage source VEE, the power supply plus terminal is connected to a second voltage source VCC. The voltage value of the reference voltage VREF is greater than the voltage value of the first voltage source VEE and less than the second voltage source VCC. The voltage value of the first voltage source VEE is greater than zero. The first terminal of the boost circuit receives the target envelope tracking input current signal, and its second terminal is connected to the inverting input terminal. The target envelope tracking input current signal is transmitted by the boost circuit to the inverting input terminal and then transmitted to the operational amplifier. The first terminal of the feedback network is connected to the inverting input terminal, and its second terminal is connected to the output terminal of the operational amplifier. It is arranged to transmit the output voltage signal of the output terminal of the operational amplifier to the inverting input terminal. The amplification circuit is arranged to perform closed-loop conversion amplification on the target envelope tracking input current signal, and the output terminal of the operational amplifier outputs an envelope tracking output voltage.

[0009] Embodiments of the present disclosure further provide an envelope tracking method. The steps of the boost circuit obtaining a target envelope tracking input current signal and transmitting the target envelope tracking input current signal to an amplification circuit, where the amplification circuit includes an operational amplifier and a feedback network, and the operational amplifier operates in a floating ground manner. The amplification circuit performing closed-loop conversion amplification on the target envelope tracking input current signal and outputting an envelope tracking output voltage.

Advantages of the Invention

[0010] In the subsequent part of the specification, other features of the present disclosure and corresponding beneficial effects are described. According to the description in the specification of the present disclosure, at least some of the beneficial effects will become clearer.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6-1

Figure 6-2

Figure 6-3

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Figure 15-1

Figure 15-2

Figure 16

Figure 17

Modes for Carrying Out the Invention

[0012] To make the objectives, technical solutions, and advantages of the present disclosure clearer, the following will use specific embodiments to further elaborate on the embodiments of the present disclosure in conjunction with the drawings. It should be noted that the specific embodiments described are not intended to limit the present disclosure, but are merely for the purpose of interpreting the present disclosure.

[0013] Embodiment 1 Referring to FIG. 3, the envelope tracking device provided in this embodiment includes an amplification circuit and a boost circuit 303. The amplification circuit includes an operational amplifier 301 and a feedback network 302. The operational amplifier 301 includes a non-inverting input terminal 3011, a power supply negative terminal V-, a power supply positive terminal V+, an output terminal 3012 of the operational amplifier, and an inverting input terminal 3013. A reference voltage VREF is applied to the non-inverting input terminal 3011. The power supply negative terminal V- is connected to a first voltage source VEE having current output / input capability. The power supply positive terminal V+ is connected to a second voltage source VCC. The voltage value of the reference voltage VREF is greater than the voltage value of the first voltage source VEE and less than the second voltage source VCC. The voltage value of the first voltage source VEE is greater than zero. The first terminal of the boost circuit 303 receives the target envelope tracking input current signal IA, and its second terminal is connected to the inverting input terminal 3013. It is arranged such that the target envelope tracking input current signal is transmitted to the inverting input terminal 3013 by the boost circuit 303 and then transmitted to the operational amplifier 301. The first terminal of the feedback network 302 is connected to the inverting input terminal 3013, and its second terminal is connected to the output terminal 3012 of the operational amplifier. It is arranged to transmit the output voltage signal of the output terminal 3012 of the operational amplifier to the inverting input terminal 3013. The amplification circuit is arranged to perform closed-loop conversion amplification on the target envelope tracking input current signal. The output terminal 3012 of the operational amplifier outputs the envelope tracking output voltage VOUT.

[0014] In some embodiments, the boost circuit transmits the target envelope tracking input current signal. To transmit the current signal, even after passing through the boost circuit, the magnitude of the current signal remains unchanged. That is, the magnitude of the current signal between the target envelope tracking input current signal flowing into the boost circuit and the target envelope tracking input current signal flowing out is the same.

[0015] In some embodiments, those skilled in the art can set the magnitude of the reference voltage VREF applied to the non-inverting input terminal of the operational amplifier as needed.

[0016] Based on the operational amplifier principle, the voltage levels of the non-inverting input terminal 3011 and the inverting input terminal 3013 are the same.

[0017] In some embodiments, the first voltage source VEE connected to the power supply minus terminal V- is smaller than the second voltage source VCC connected to the power supply plus terminal V+, and does not directly connect to the ground. In this way, the actual power supply voltage of the operational amplifier is the voltage difference between the power supply plus terminal V+ and the power supply minus terminal V-. This reduces the power supply voltage range for the actual operation of the operational amplifier, which is equivalent to the operational amplifier operating in a floating ground state, reducing the power consumption of the operational amplifier and improving the amplification efficiency.

[0018] Note that the voltages among the three, namely the first voltage source VEE connected to the power supply minus terminal V-, the second voltage source VCC connected to the power supply plus terminal V+, and the reference voltage VREF, satisfy VCC > VREF > VEE > 0V.

[0019] In some embodiments, the first voltage source has current output / input capabilities.

[0020] In some embodiments, referring to FIG. 4, the feedback network is formed by a feedback resistor R6 connected between the inverting input terminal 3013 of the operational amplifier and the output terminal 3012 of the operational amplifier. Based on the circuit principle, in an ideal situation, the magnitude of the current flowing through the feedback resistor R6 is consistent with the magnitude of the current of the target envelope tracking input current signal IA. After passing through the boost circuit, the target envelope tracking input current signal IA is applied to the inverting input terminal 3013 of the operational amplifier. After being converted by the operational amplifier 301 and the feedback resistor R6, the amplified envelope tracking output voltage VOUT is obtained. In some embodiments, the conversion formula between the target envelope tracking input current signal IA and the output envelope tracking output voltage VOUT satisfies VOUT = VREF + R6 * IA. The amplitude of the VOUT output voltage is between VREF and VCC. With this circuit, the target envelope tracking input current signal IA is amplified to become the output envelope tracking output voltage VOUT. The absolute value of the actual operating voltage of the operational amplifier OP4 itself is VCC - VEE, and the actual output swing is between VREF - VEE and VCC - VEE. As a result, the operational amplifier can operate in a floating ground manner, reducing the loss of the operational amplifier OP4 itself and improving the efficiency.

[0021] In some embodiments, as shown in FIG. 5, the envelope tracking device further includes a constant current source signal circuit 304. The constant current source signal circuit 304 is connected to the first end of the boost circuit 303 and is arranged to convert the envelope tracking input current signal IA1 into the target envelope tracking input current signal IA. Note that to meet the requirements of the boost circuit, the signal direction of the target envelope tracking input current signal is a negative current, that is, its signal direction flows from the second end of the boost circuit to the first end of the boost circuit. The constant current source signal circuit 304 provides a DC constant current source current signal IA2 with a constant output magnitude. Regarding the direction and magnitude of the constant current source current signal IA2, those skilled in the art can set it as needed.

[0022] In some embodiments, as shown in FIG. 6-1, when the envelope tracking input current signal IA1 is a negative current and the constant current source current signal IA2 is a positive current, the constant current source current signal IA2 of the constant current source signal circuit 304 is subtracted from the envelope tracking input current signal IA1 to obtain the target envelope tracking input current signal IA, that is, IA = IA1 - IA2. Note that IA2 ≤ IA1. When the envelope tracking input current signal IA1 is a negative current, it is determined whether to arrange the constant current source signal circuit 304 as needed.

[0023] In some embodiments, as shown in FIG. 6-2, when both the envelope tracking input current signal IA1 and the constant current source current signal IA2 are negative currents, the constant current source current signal IA2 of the constant current source signal circuit 304 is added to the envelope tracking input current signal IA1 to obtain the target envelope tracking input current signal IA, that is, IA = IA1 + IA2. In this case, the magnitude relationship between IA1 and IA2 is not limited.

[0024] Note that for the constant current source signal circuit 304, the current signal flowing into the constant current source signal circuit 304 is a negative current, and the current signal flowing out of the constant current source signal circuit 304 is a positive current.

[0025] In some embodiments, as shown in FIG. 6-3, when the envelope tracking input current signal IA1 is a negative current, the constant current source signal circuit may not be arranged.

[0026] Note that when the envelope tracking input current signal IA1 is a negative current, the current direction of the constant current source current signal IA2 may be a positive current or a negative current. When the envelope tracking input current signal IA1 is a positive current, the current direction of the constant current source current signal IA2 can only be other than a negative current.

[0027] In some embodiments, as shown in FIG. 7, when the envelope tracking input current signal IA1 is a positive current, the envelope tracking input current signal IA1 is obtained by subtracting the envelope tracking input current signal IA1 from the constant current source current signal IA2 of the constant current source signal circuit 304, that is, IA = IA2 - IA1. Note that IA1 ≤ IA2. Note that when the envelope tracking input current signal IA1 is a positive current, a constant current source signal circuit must be arranged, and thereby, a DC current signal constant current source current signal IA2 with a constant magnitude is generated to process the envelope tracking input current signal IA1, so that the target envelope tracking input current signal IA meets the requirements.

[0028] In some embodiments, as shown in FIG. 8, the envelope tracking device further includes a switch circuit 305 connected to the output end 3012 of the operational amplifier and the load 306. The switch circuit 305 is arranged to reduce the output current of the operational amplifier 301 by providing a part of the current of the load 306.

[0029] In some embodiments, the output parallel connection switch circuit provides a required part of the current of the load, reduces the output current of the operational amplifier, and improves the efficiency of the operational amplifier. Note that in some embodiments, the load may be a power amplifier.

[0030] In some embodiments, as shown in FIG. 9, the envelope tracking device further includes a digital-to-analog converter DAC 307. The positive and negative power supply ends of the digital-to-analog converter 307 are grounded, and its output end is connected to the first end of the boost circuit 303. It is arranged to output the envelope tracking input current signal IA1 by conversion. Note that when a constant current source signal circuit is not arranged between the digital-to-analog converter DAC and the boost circuit, the envelope tracking input current signal IA1 is the target envelope tracking input current signal IA. Note that when the envelope tracking input current signal IA1 is a negative current, the current flows from the output end of the digital-to-analog converter into the digital-to-analog converter.

[0031] In some embodiments, as shown in FIG. 10, the envelope tracking device further includes a bias resistor R7. The bias resistor R7 is connected between the output terminal of the digital-to-analog converter 307 and the first terminal of the boost circuit 303, and is arranged to provide the necessary bias voltage for normal operation to the digital-to-analog converter 307. In some embodiments, the magnitude of the bias voltage is VREF - the voltage drop of the boost circuit itself - the voltage drop of R7.

[0032] In some embodiments, the first terminal of the bias resistor is connected to the output terminal of the digital-to-analog converter, and its second terminal is connected to the first terminal of the boost circuit.

[0033] In some embodiments, the boost circuit includes a Zener diode and a capacitor connected in parallel. The anode of the Zener diode is connected to the capacitor in parallel, and the end where the anode is connected to the capacitor is taken as the first terminal of the boost circuit.

[0034] As shown in FIG. 11, the boost circuit is formed by a Zener diode VD1 and a capacitor C1 connected in parallel. In this case, the target envelope tracking input current signal IA is connected from the end of the Zener diode VD1 where it is connected to the capacitor C1 in parallel to the second terminal of the bias resistor R7, and provides the necessary bias voltage during operation to the output port of the digital-to-analog converter 307. The magnitude of the voltage is VREF - the voltage drop of VD1 - the voltage drop of R7. One end of the cathode of the Zener diode VD1 is connected to one end of the capacitor C1 in parallel and then connected to the inverting input terminal 3013 of the operational amplifier 301. After the voltage is increased by the Zener diode VD1, the target envelope tracking input current signal IA is transmitted to the inverting input terminal 3013 of the operational amplifier 301. The target envelope tracking input current signal IA flows through both the capacitor C1 and the Zener diode VD1, and most of the current signal flows through the capacitor C1, so that the voltage stabilization effect of the Zener diode VD1 is better.

[0035] In addition, according to the actual application requirements, the resistance value of the bias resistor can be set. The minimum value can be set to 0 Ω. The bias resistor provides the necessary bias voltage for the operation at the DAC output terminal.

[0036] In some embodiments, the boost circuit includes a constant voltage power supply.

[0037] As shown in FIG. 12, the boost circuit is composed of a constant voltage power supply 308. The positive terminal of the constant voltage power supply 308 is connected to the inverting input terminal 3013, and the negative terminal is connected to the second terminal of the bias resistor R7. The constant voltage power supply 308 provides an appropriate stable voltage, transmits the target envelope tracking input current signal IA to the inverting input terminal 3013 of the operational amplifier 301, and after being amplified by the operational amplifier 301, is arranged to obtain the envelope tracking output voltage VOUT. In this case, the necessary bias voltage during operation is provided to the output port of the digital-to-analog converter 307. The magnitude of this voltage is VREF - constant voltage power supply voltage - R7 voltage drop.

[0038] In some embodiments, the switch circuit is composed of a BUCK circuit. an inductor whose first terminal is connected to the output terminal of the operational amplifier; a first MOSFET whose source is grounded and whose drain is connected to the second terminal of the inductor; a second MOSFET whose drain is connected to the power supply and whose source is connected to the second terminal of the inductor.

[0039] As shown in FIG. 13, the switch circuit includes an inductor L1 whose first terminal is connected to the output terminal 3012 of the operational amplifier, a first MOSFET Q1 whose source is grounded and whose drain is connected to the second terminal of the inductor L1, and a second MOSFET Q2 whose drain is connected to the power supply VCC and whose source is connected to the second terminal of the inductor L2. In some embodiments, the switch circuit is further connected to a load. The BUCK circuit provides some of the required current to the load, reduces the output current of the operational amplifier, thereby reducing the power consumption of the operational amplifier and improving the efficiency.

[0040] For the convenience of understanding, in the following, the envelope tracking device provided by the present disclosure will be further described by way of specific embodiments.

[0041] As shown in FIG. 14, the envelope tracking device includes a digital-to-analog converter 307, a bias resistor R7, a constant current source signal circuit 304, a boost circuit formed by a capacitor C1 and a Zener diode VD1, an amplifier circuit, an inductor L11, a BUCK switch circuit formed by a first MOSFET Q1 and a second MOSFET Q2. The amplifier circuit includes an operational amplifier 301 and a feedback network composed of a feedback resistor R6. For the connection relationship between each part, reference may be made to FIG. 14. The power supply minus end of the digital-to-analog converter DAC307 is grounded, and its output end is connected in series to the bias resistor R7. The other end of the bias resistor R7 is connected to one side of the Zener diode VD1 where the anode is connected in parallel to the capacitor C1. Also, the anode of the Zener diode VD1 is further connected to the constant current source signal circuit 304. One end of the cathode of the Zener diode VD1 is connected to the inverting input end 3013 of the operational amplifier 301. The operational amplifier 301 operates in a floating ground manner. The operational amplifier 301 includes a non-inverting input end 3011, a power supply minus end V-, a power supply plus end V+, an output end 3012 of the operational amplifier, and an inverting input end 3013. A reference voltage VREF is applied to the non-inverting input end 3011. The power supply minus end V- is connected to a first voltage source VEE having current output / input capability. The power supply plus end V+ is connected to a second voltage source VCC. The voltage value of the reference voltage VREF is greater than the voltage value of the first voltage source VEE and less than the second voltage source VCC. The voltage value of the first voltage source VEE is greater than zero. The first end of the feedback resistor R6 is connected to the inverting input end 3013, and its second end is connected to the output end 3012 of the operational amplifier, and is arranged to transmit the output voltage signal of the output end 3012 of the operational amplifier to the inverting input end 3013. The first end of the inductor L1 is connected to the output end of the operational amplifier. The source of the first MOSFET Q1 is grounded, and its drain is connected to the second end of the inductor L1. The drain of the second MOSFET Q2 is connected to the power supply, and its source is connected to the second end of the inductor L1.

[0042] The digital - analog converter DAC 307 outputs an envelope - tracking input current signal IA1, then superimposes a constant - current source current signal IA2 of the constant - current source signal circuit, generates a target envelope - tracking input current signal IA, and transmits the envelope - tracking input current signal to the inverting input terminal 3013 of the operational amplifier 301 via a boosting circuit composed of a capacitor C1 and a Zener diode VD1. The amplification circuit is arranged to perform closed - loop conversion amplification on the target envelope - tracking input current signal, and the output terminal 3012 of the operational amplifier outputs an envelope - tracking output voltage VOUT. The feedback resistor R6 of the amplification circuit transmits the output voltage signal of the output terminal 3012 of the operational amplifier to the inverting input terminal 3013 to form closed - loop conversion amplification.

[0043] Note that depending on different DAC model numbers, the output envelope - tracking input current signal may be either a positive current, that is, the current direction flows out from the DAC output terminal, or a negative current, that is, the current direction flows into the DAC output terminal. When the output envelope - tracking input current signal is a positive current, it is necessary to arrange a constant - current source signal circuit for converting the envelope - tracking input current signal into a target envelope - tracking input current signal that meets subsequent requirements.

[0044] Based on circuit principles, in an ideal situation, the magnitude of the current flowing through the resistor R6 is consistent with the magnitude of the input envelope - tracking input current signal.

[0045] Note that for transmitting the current signal, even after passing through the boosting circuit, the magnitude of the target envelope - tracking input current signal remains unchanged. That is, when there is a constant - current source circuit, after superimposing the envelope - tracking input current signal and the constant - current source current signal, the magnitude of the obtained target envelope - tracking input current signal is consistent with the magnitude of the target envelope - tracking input current signal flowing out from the boosting circuit. When there is no constant - current source circuit, the magnitudes of the envelope - tracking input current signal and the target envelope - tracking input current signal are consistent.

[0046] In some embodiments, a bias resistor provides the necessary bias voltage for normal operation to the DAC, and the magnitude of the bias voltage is VREF - boost circuit self-pressure drop - feedback resistor pressure drop.

[0047] In some embodiments, the conversion formula between the target envelope tracking input current signal and the output envelope tracking output voltage VOUT is satisfied by the output envelope tracking output voltage VOUT = reference voltage VREF + resistance value of the feedback resistor * target envelope tracking input current signal IA. Note that since the boost current transmits the current signal, when there is no constant current source circuit in the circuit, the magnitudes of the target envelope tracking input current signal IA and the envelope tracking input current signal IA1 are the same.

[0048] Note that the amplitude of the output voltage of the output envelope tracking output voltage VOUT is between VREF and VCC.

[0049] With the above circuit, the envelope tracking input current signal IA1 is amplified to become the output envelope tracking output voltage VOUT. The absolute value of the actual operating voltage of the operational amplifier 301 itself is VCC - VEE, and the actual output swing is between VREF - VEE and VCC - VEE. Thus, the operational amplifier can operate in a floating ground manner, reducing the loss of the operational amplifier 301 itself and improving the efficiency. For example, when VCC = 30V, VREF = 10V, and VEE = 8V, the power supply voltage of the operational amplifier is 22V. For the operational amplifier itself, the output voltage is within the range of 2V to 20V. Compared with the case where the operational amplifier operates directly grounded, for the same amplification result, the operational amplifier is supplied with 30V of power, and the output voltage is in the range of 12V to 30V, reducing the amplification loss and improving the efficiency.

[0050] As shown in FIGS. 15-1 and 15-2, when the envelope tracking device of the embodiment of the present disclosure is operating, signal waveforms at different positions are shown. IA is the target envelope tracking input current signal, which is a signal that changes at a high frequency. VOUT is the output envelope tracking output voltage after amplification by the circuit, and its amplitude value is between VREF and VCC. The input current signal IA and the output voltage VOUT have a linear amplification relationship. The power supply voltage at the positive power supply terminal of the operational amplifier is VCC, the power supply voltage at its negative power supply terminal is VEE, and the reference voltage VREF is applied to its non-inverting input terminal, where VRFE > VEE > 0.

[0051] The envelope tracking device provided by the embodiment of the present disclosure includes an amplification circuit composed of an operational amplifier and a feedback network, and a boost circuit. After the target envelope tracking input current signal is transmitted by the boost circuit, it is converted using the amplification circuit to obtain the envelope tracking output voltage. In the related art, when the amplitude of the output voltage of envelope tracking is high and the swing is large, in the linear amplification process, the loss of the operational amplifier is large and the efficiency is low. This solves the problem and realizes a more effective conversion for the target envelope tracking input current signal, improves the conversion efficiency of the operational amplifier, reduces the amplification loss, and improves the user experience.

[0052] Preferably, the negative power supply terminal of the DAC is grounded, the negative terminal of the operational amplifier is not directly grounded. Even if the envelope tracking input current signal output from the DAC passes through the boost circuit, it is not affected. The current signal is applied to the inverting input terminal of the operational amplifier, amplified linearly by the operational amplifier, and then output for use by the subsequent power amplification load. This solves the problem related to signal transmission caused by the DAC and the operational amplifier not operating while being grounded at the same time.

[0053] Preferably, the negative power supply terminal V- of the operational amplifier is connected to a high voltage source (the power supply voltage of the power supply V+ is higher than that of the V- terminal), and is not directly grounded. In this way, the actual power supply voltage of the operational amplifier is the voltage difference between the positive power supply terminal V+ and the negative power supply terminal V-, which reduces the power supply voltage range of the actual operation of the operational amplifier, and is equivalent to the operational amplifier operating in a floating ground state, reducing the power consumption of the operational amplifier and improving the amplification efficiency.

[0054] Preferably, when the envelope tracking input current signal output from the DAC is positive, one constant current source circuit is added, subtraction is performed on the two current signals, and then the target envelope tracking input current signal for the operational amplifier is obtained.

[0055] Preferably, when the envelope tracking input current signal output from the DAC is negative, if necessary, one constant current source circuit is added, subtraction is performed on the two current signals, and then the target envelope tracking input current signal for the operational amplifier is obtained.

[0056] Preferably, the output parallel connection switch circuit provides a part of the current required by the load of the power amplifier, reduces the output current of the operational amplifier, and improves the efficiency of the operational amplifier.

[0057] Embodiment 2 This embodiment further provides an envelope tracking method. As shown in FIG. 16, the method includes: S1601: The boosting circuit obtains the target envelope tracking input current signal; S1602: Transmit the target envelope tracking input current signal to the amplification circuit; S1603: The amplification circuit performs closed-loop conversion amplification on the target envelope tracking input current signal and outputs the envelope tracking output voltage.

[0058] In some embodiments, the above envelope tracking method can be applied to the envelope tracking device described in any one of the above embodiments.

[0059] In some embodiments, the target envelope tracking input current signal may be directly the envelope current signal output from a digital-to-analog converter (DAC), or may be the current signal obtained after further processing the envelope current signal output from the digital-to-analog converter (DAC).

[0060] In some embodiments, the amplification circuit includes an operational amplifier and a feedback network, and the operational amplifier operates in a floating ground mode.

[0061] In some embodiments, the negative power supply terminal of the operational amplifier is connected to a high first voltage source VEE, the first voltage source VEE is smaller than a second voltage source VCC connected to the positive power supply terminal of the operational amplifier, a reference voltage VREF is applied to the non-inverting input terminal of the operational amplifier, and the relationship among the three is VCC > VREF > VEE > 0V. By the above arrangement, the floating ground operation of the operational amplifier is realized.

[0062] Note that in order to transmit the current signal, even if it passes through a boost circuit, the magnitude of the target envelope tracking input current signal remains unchanged. That is, if there is a constant current source circuit, after superimposing the envelope tracking input current signal and the constant current source current signal, the magnitude of the obtained target envelope tracking input current signal is consistent with the magnitude of the target envelope tracking input current signal flowing out from the boost circuit. If there is no constant current source circuit, the magnitudes of the envelope tracking input current signal and the target envelope tracking input current signal are consistent.

[0063] In some embodiments, those skilled in the art may set the magnitude of the reference voltage VREF applied to the non-inverting input terminal of the operational amplifier as needed.

[0064] Note that based on the operational amplifier principle, the voltage levels of the non-inverting input terminal 3011 and the inverting input terminal 3013 are the same.

[0065] In some embodiments, the first voltage source VEE connected to the negative power supply terminal V- is smaller than the second voltage source VCC connected to the positive power supply terminal V+, and is not directly grounded. Thus, the actual power supply voltage of the operational amplifier is the voltage difference between the positive power supply terminal V+ and the negative power supply terminal V-, which reduces the power supply voltage range of the actual operation of the operational amplifier. This corresponds to the operational amplifier operating in a floating ground state, reducing the power consumption of the operational amplifier and improving the amplification efficiency.

[0066] In some embodiments, it has a first voltage source current output / input capability.

[0067] In some embodiments, the feedback network in the amplification circuit is formed by a feedback resistor R, and the feedback resistor is connected between the inverting input terminal and the output terminal of the operational amplifier. Based on the circuit principle, in an ideal situation, the magnitude of the current flowing through the feedback resistor is consistent with the magnitude of the current of the target envelope tracking input current signal IA. The target envelope tracking input current signal IA is applied to the inverting input terminal of the operational amplifier after passing through a boost circuit, and after being converted by the operational amplifier and the feedback resistor R, the amplified envelope tracking output voltage VOUT is obtained. In some embodiments, the conversion formula between the target envelope tracking input current signal IA and the output envelope tracking output voltage VOUT satisfies VOUT = VREF + R6 * IA. The amplitude of the VOUT output voltage is between VREF and VCC. With this circuit, the target envelope tracking input current signal IA is amplified to become the output envelope tracking output voltage VOUT. The absolute value of the actual operating voltage of the operational amplifier OP4 itself is VCC - VEE, and the actual output swing is between VREF - VEE and VCC - VEE. Thereby, the operational amplifier can operate in a floating ground state, reducing the loss of the operational amplifier OP4 itself and improving the efficiency.

[0068] In some embodiments, the amplification circuit transmits the output voltage signal of the operational amplifier back to the negative terminal of the operational amplifier through a feedback network.

[0069] In some embodiments, before obtaining the target envelope tracking input current signal, the constant current source signal circuit further comprises a step of converting the envelope tracking input current signal into the target envelope tracking input current signal.

[0070] It should be noted that the target envelope tracking input current signal is a current signal that meets the requirements of the boost circuit, and its signal direction is a negative current, that is, its signal direction flows from the second end of the boost circuit to the first end of the boost circuit. The constant current source signal circuit provides a DC constant current source current signal with a constant output magnitude. Regarding the direction and magnitude of the constant current source current signal, those skilled in the art can set it as needed.

[0071] In some embodiments, when the envelope tracking input current signal is a negative current and the constant current source current signal is a positive current, the target envelope tracking input current signal is obtained by subtracting the constant current source current signal of the constant current source signal circuit from the envelope tracking input current signal, and the envelope tracking input current signal is greater than the constant current source current signal of the constant current source signal circuit.

[0072] In some embodiments, when the envelope tracking input current signal is a negative current and the constant current source current signal is a negative current, the target envelope tracking input current signal is obtained by adding the constant current source current signal of the constant current source signal circuit to the envelope tracking input current signal.

[0073] It should be noted that for the constant current source signal circuit 304, the current signal flowing into the constant current source signal circuit 304 is a negative current, and the current signal flowing out of the constant current source signal circuit 304 is a positive current.

[0074] It should be noted that when the envelope tracking input current signal is a negative current, it is necessary to determine whether to arrange the constant current source signal circuit as needed.

[0075] In some embodiments, when the envelope tracking input current signal is a positive current, the target envelope tracking input current signal is obtained by subtracting the envelope tracking input current signal from the constant current source current signal of the constant current source signal circuit, and the envelope tracking input current signal is less than the constant current source current signal of the constant current source signal circuit.

[0076] In addition, when the envelope tracking input current signal is a positive current, a constant current source signal circuit is necessarily arranged, thereby generating a DC current signal constant current source current signal with a constant magnitude, and processing the envelope tracking input current signal so that the target envelope tracking input current signal meets the requirements.

[0077] In addition, the constant current source current signal may be a positive current or a negative current. Regarding the magnitude and direction of the constant current source current signal, those skilled in the art may set it based on the magnitude and direction of the corresponding envelope tracking input current signal, thereby processing the envelope tracking input current signal through the DC current signal constant current source current signal with a constant magnitude generated from the constant current source signal circuit so that the target envelope tracking input current signal meets the requirements.

[0078] In addition, when the envelope tracking input current signal IA1 is a negative current, the current direction of the constant current source current signal IA2 may be a positive current or a negative current. When the envelope tracking input current signal IA1 is a positive current, the current direction of the constant current source current signal IA2 can only be other than a negative current.

[0079] In some embodiments, the envelope tracking method further includes a step of reducing the output current of the operational amplifier by the switch circuit providing a part of the current of the load.

[0080] In some embodiments, the output parallel connection switch circuit provides a required part of the current of the load, reduces the output current of the operational amplifier, and improves the efficiency of the operational amplifier. Note that the load may be a power amplifier.

[0081] In some embodiments, the envelope tracking method further includes a step of outputting the envelope tracking input current signal by a digital-to-analog converter.

[0082] Note that the negative power supply terminal of the digital-to-analog converter (DAC) is grounded, and its output terminal is connected to the first terminal of the boost circuit, and is arranged to output an envelope tracking input current signal by conversion.

[0083] Note that when a constant current source signal circuit is not arranged between the digital-to-analog converter (DAC) and the boost circuit, the envelope tracking input current signal is the target envelope tracking input current signal. Note that when the envelope tracking input current signal is a negative current, the current flows from the output terminal of the digital-to-analog converter into the digital-to-analog converter.

[0084] In some embodiments, the envelope tracking method further comprises the step of providing a bias voltage required for normal operation to the digital-to-analog converter by a bias resistor.

[0085] In some embodiments, the magnitude of the bias voltage is VREF - the voltage drop of the boost circuit itself - the voltage drop of R7.

[0086] In some embodiments, the boost circuit comprises a Zener diode and a capacitor connected in parallel, and the anode of the Zener diode is connected to the capacitor in parallel at the end which is the first terminal of the boost circuit.

[0087] In some embodiments, the boost circuit is formed by a Zener diode and a capacitor connected in parallel. In this case, the target envelope tracking input current signal is connected from the end of the Zener diode connected in parallel to the capacitor to the second end of the bias resistor, and provides the required bias voltage during operation to the output port of the digital-to-analog converter. The magnitude of the voltage is VREF - Zener diode voltage drop - bias resistor voltage drop. One end of the cathode of the Zener diode is connected to one end of the capacitor in parallel and then connected to the inverting input terminal of the operational amplifier. After the voltage is increased by the Zener diode, the target envelope tracking input current signal is transmitted to the inverting input terminal of the operational amplifier. The target envelope tracking input current signal flows through both the capacitor and the Zener diode, and most of the current signal flows through the capacitor, thereby improving the voltage stabilizing effect of the Zener diode.

[0088] In some embodiments, the boost circuit includes a constant voltage power supply.

[0089] In some embodiments, the constant voltage power supply provides an appropriate stable voltage, transmits the target envelope tracking input current signal to the inverting input terminal of the operational amplifier, and after being amplified by the operational amplifier, is arranged to obtain the envelope tracking output voltage VOUT. In this case, the required bias voltage during operation is provided to the output port of the digital-to-analog converter. The magnitude of the voltage is VREF - constant voltage power supply voltage - bias resistor voltage drop.

[0090] In some embodiments, the switch circuit includes an inductor whose first end is connected to the output terminal of the operational amplifier, a first MOSFET whose source is grounded and whose drain is connected to the second end of the inductor, and a second MOSFET whose drain is connected to the power supply and whose source is connected to the second end of the inductor.

[0091] In some embodiments, the switch circuit is further connected to a load, and the BUCK circuit reduces the output current of the operational amplifier, thereby reducing the power consumption of the operational amplifier and improving the efficiency.

[0092] Embodiment 3 The following further describes the above envelope tracking method with specific embodiments. Referring to FIG. 17, as shown in FIG. 17, the specific envelope tracking method is as follows: S1701: The digital-to-analog converter outputs an envelope tracking input current signal. S1702: The constant current source signal circuit converts the envelope tracking input current signal into a target envelope tracking input current signal. S1703: The boost circuit obtains the target envelope tracking input current signal. S1704: Transmit the target envelope tracking input current signal to the amplifier circuit. S1705: The amplifier circuit performs closed-loop conversion amplification on the target envelope tracking input current signal and outputs an envelope tracking output voltage. S1706: By the switch circuit providing a part of the current of the load, reducing the output current of the operational amplifier.

[0093] Note that the amplifier circuit includes an operational amplifier and a feedback network. The feedback network transmits the output voltage signal at the output end of the operational amplifier to the inverting input end of the operational amplifier and is arranged to form closed-loop conversion amplification.

[0094] Note that depending on different DAC type numbers, the output envelope tracking input current signal is either a positive current, that is, the current direction flows out from the DAC output end, or a negative current, that is, the current direction flows into the DAC output end. When the output envelope tracking input current signal is a positive current, it is necessary to arrange a constant current source signal circuit for converting the envelope tracking input current signal into a target envelope tracking input current signal that meets subsequent requirements.

[0095] Note that based on the circuit principle, in an ideal situation, the magnitude of the current flowing through resistor R6 is consistent with the magnitude of the input envelope tracking input current signal.

[0096] Note that for transmitting the current signal, even after passing through the boost circuit, the magnitude of the target envelope tracking input current signal remains unchanged. That is, when there is a constant current source circuit, after superimposing the envelope tracking input current signal and the constant current source current signal, the magnitude of the obtained target envelope tracking input current signal is consistent with the magnitude of the target envelope tracking input current signal flowing out from the boost circuit. When there is no constant current source circuit, the magnitudes of the envelope tracking input current signal and the target envelope tracking input current signal are the same.

[0097] In some embodiments, a bias resistor provides the necessary bias voltage for normal operation to the DAC, and the magnitude of the bias voltage is VREF - the voltage drop of the boost circuit itself - the voltage drop of the feedback resistor.

[0098] In some embodiments, the conversion formula between the target envelope tracking input current signal and the output envelope tracking output voltage VOUT is satisfied by the output envelope tracking output voltage VOUT = reference voltage VREF + the resistance value of the feedback resistor * the target envelope tracking input current signal IA. Note that for transmitting the current signal by the boost current, when there is no constant current source circuit in the circuit, the magnitudes of the target envelope tracking input current signal IA and the envelope tracking input current signal IA1 are the same.

[0099] Note that the amplitude of the output voltage of the output envelope tracking output voltage VOUT is between VREF and VCC.

[0100] With the above circuit, the envelope tracking input current signal IA1 is amplified to become the output envelope tracking output voltage VOUT. The absolute value of the actual operating voltage of the operational amplifier itself is VCC - VEE, and the actual output swing is between VREF - VEE and VCC - VEE. Thus, the operational amplifier can operate in a floating ground manner, reducing the loss of the operational amplifier itself and improving the efficiency. For example, when VCC = 30V, VREF = 10V, and VEE = 8V, the power supply voltage of the operational amplifier is 22V. For the operational amplifier itself, the output voltage is within the range of 2 - 20V. Compared with the case where the operational amplifier operates directly grounded, for the same amplification result, the operational amplifier is supplied with 30V of power, and the output voltage is in the range of 12 - 30V, reducing the amplification loss and improving the efficiency.

Industrial Applicability

[0101] In the envelope tracking method provided by the embodiments of the present disclosure, a boost circuit is used to obtain a target envelope tracking input current signal. The boost circuit transmits the target envelope tracking input current signal to an amplification circuit. The amplification circuit includes an operational amplifier and a feedback network. The operational amplifier operates in a floating ground manner. The amplification circuit performs closed-loop conversion amplification on the target envelope tracking input current signal to output an envelope tracking output voltage. In the related prior art, when the amplitude of the output voltage of envelope tracking is high and the swing is large, in the linear amplification process, the loss of the operational amplifier is large and the efficiency is low. This solves the problem and realizes more effective amplification for the target envelope tracking input current signal, improves the conversion efficiency of the operational amplifier, reduces the amplification loss, and improves the user experience.

[0102] In some cases, at least one step shown or described can be executed according to an order different from that described in the above embodiments.

[0103] The above content is a more detailed description of the embodiments of the present disclosure in combination with specific embodiments, and the specific implementation of the present disclosure is not limited to these descriptions. For those skilled in the art, several simple deductions or substitutions may be made on the premise of not departing from the concept of the present disclosure, and all of them should be included in the protection scope of the present disclosure.

Claims

1. An envelope tracking device, wherein the envelope tracking device includes an amplifier circuit and a boost circuit, the amplifier circuit includes an operational amplifier and a feedback network, the operational amplifier includes a non-inverting input terminal, a power supply negative terminal, a power supply positive terminal, an output terminal of the operational amplifier, and an inverting input terminal. A reference voltage VREF is applied to the non-inverting input terminal. The power supply negative terminal is connected to a first voltage source VEE. The power supply positive terminal is connected to a second voltage source VCC. The voltage value of the reference voltage VREF is greater than the voltage value of the first voltage source VEE and less than the second voltage source VCC. The voltage value of the first voltage source VEE is greater than zero. A first terminal of the boost circuit receives a target envelope tracking input current signal, and a second terminal thereof is connected to the inverting input terminal. The target envelope tracking input current signal is transmitted to the inverting input terminal by the boost circuit and then transmitted to the operational amplifier. The boost circuit increases the voltage or provides a stable voltage without changing the magnitude of the target envelope tracking input current signal passing through the boost circuit so that the voltage value of the inverting input terminal of the operational amplifier is greater than the voltage value of the first voltage source VEE. A first terminal of the feedback network is connected to the inverting input terminal, and a second terminal thereof is connected to the output terminal of the operational amplifier. The output voltage signal of the output terminal of the operational amplifier is arranged to be transmitted to the inverting input terminal. The amplifier circuit is arranged to perform closed-loop conversion amplification on the target envelope tracking input current signal. An output terminal of the operational amplifier is an envelope tracking device that outputs an envelope tracking output voltage.

2. The envelope tracking device further includes a constant current source signal circuit, wherein the constant current source signal circuit is connected to the first terminal of the boost circuit and is arranged to convert an envelope tracking input current signal into a target envelope tracking input current signal. The envelope tracking device according to claim 1.

3. The envelope tracking device further includes a switch circuit, the switch circuit is connected to the output end of the operational amplifier and the load, and is arranged to reduce the output current of the operational amplifier. The switch circuit is composed of a BUCK circuit and includes an inductor with its first end connected to the output end of the operational amplifier, a first MOSFET with its source grounded and its drain connected to the second end of the inductor, and a second MOSFET with its drain connected to the power supply and its source connected to the second end of the inductor. The envelope tracking device according to claim 1.

4. The envelope tracking device further includes a digital-to-analog converter. The power supply minus end of the digital-to-analog converter is grounded, and its output end is connected to the first end of the boost circuit and is arranged to output an envelope tracking input current signal by conversion. The envelope tracking device according to any one of claims 1 to 3.

5. The envelope tracking device further includes a bias resistor. The bias resistor is connected between the output end of the digital-to-analog converter and the first end of the boost circuit and is arranged to provide a necessary bias voltage for normal operation to the digital-to-analog converter. The envelope tracking device according to claim 4.

6. The boost circuit includes a Zener diode and a capacitor connected in parallel. The end of the Zener diode where the anode is connected in parallel to the capacitor is used as the first end of the boost circuit, and the end of the Zener diode where the cathode is connected in parallel to the capacitor is used as the second end of the boost circuit. The envelope tracking device according to any one of claims 1 to 3.

7. The boost circuit is composed of a constant voltage power supply, and the plus end of the constant voltage power supply is connected to the inverting input end. The envelope tracking device according to any one of claims 1 to 3.

8. An envelope tracking method, the envelope tracking method includes The boosting circuit is a step of obtaining a target envelope tracking input current signal and transmitting the target envelope tracking input current signal to an amplifying circuit. The amplifying circuit includes an operational amplifier and a feedback network. The operational amplifier operates in a floating ground mode. The boosting circuit increases the voltage or provides a stable voltage without changing the magnitude of the target envelope tracking input current signal passing through the boosting circuit, such that the voltage value at the inverting input terminal of the operational amplifier is greater than the voltage value of the first voltage source VEE at the power supply minus terminal of the operational amplifier. The amplifying circuit performs closed-loop conversion amplification on the target envelope tracking input current signal to output an envelope tracking output voltage. The envelope tracking method includes these steps.

9. Before obtaining the target envelope tracking input current signal, The envelope tracking method according to claim 8 further includes a step of converting an envelope tracking input current signal into the target envelope tracking input current signal by a constant current source signal circuit.

10. The envelope tracking method includes a step of reducing the output current of the operational amplifier by a switch circuit. The switch circuit is composed of a BUCK circuit and includes an inductor with its first end connected to the output end of the operational amplifier, a first MOSFET with its source grounded and its drain connected to the second end of the inductor, and a second MOSFET with its drain connected to the power supply and its source connected to the second end of the inductor. The envelope tracking method according to claim 9 further includes this step.

11. The envelope tracking method The envelope tracking method according to claim 9 further includes a step of outputting the envelope tracking input current signal by a digital-to-analog converter.

12. The envelope tracking method The envelope tracking method according to claim 11 further includes a step of providing a bias voltage required for normal operation to the digital-to-analog converter by a bias resistor.

13. The boosting circuit includes a Zener diode and a capacitor connected in parallel. The end of the Zener diode where the anode is connected in parallel to the capacitor is used as the first end of the boosting circuit, and the end of the Zener diode where the cathode is connected in parallel to the capacitor is used as the second end of the boosting circuit. The envelope tracking method according to any one of claims 8 to 10 is as described above.

14. The boosting circuit is composed of a constant voltage power supply, and the positive terminal of the constant voltage power supply is connected to the inverting input terminal of the operational amplifier. The envelope tracking method according to any one of claims 8 to 10.

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