Digital envelope tracking supply modulator for RF power amplifier

Abstract

The present invention relates to a digital envelope tracking supply modulator for an RF power amplifier. The digital envelope tracking supply modulator for an RF power amplifier according to an aspect of the present invention is a digital envelope tracking supply modulator for an RF power amplifier, the modulator variably operating a power supply according to the envelope of an RF signal and comprising: at least two voltage sources; at least one first switch, each of which is turned on to connect two different voltage sources of the at least two voltage sources in series; and at least one second switch which, when the first switch is turned off, is turned on to provide a current path bypassing the first switch and any one voltage source connected to the first switch.

Description

Digital envelope tracking power modulator for RF power amplifier

[0001] The present invention relates to a digital envelope tracking power modulator for an RF power amplifier.

[0002] RF power amplifiers designed to linearly amplify RF signals suffer from low power efficiency and suffer from high energy consumption and heat generation issues. In particular, the efficiency of RF power amplifiers decreases even further when amplifying Orthogonal Frequency Division Multiplexing (OFDM) signals with a high Peak-to-Average Power Ratio (PAPR).

[0003] In this regard, Envelope Tracking (ET) technology is being disclosed to improve back-off power efficiency by modulating the power supply voltage of an RF power amplifier. ET technology increases the back-off power efficiency of an RF power amplifier by using a high-speed supply modulator (SM) to supply a power supply voltage to the RF power amplifier that can track the envelope of a communication signal.

[0004] Conventional analog ETs primarily use power modulators with a hybrid structure, such as that shown in Fig. 11, to track the envelope of wide-bandwidth wireless communication signals and achieve high-efficiency characteristics. The hybrid power modulator features a parallel structure of an analog linear amplifier with a push-pull output buffer and a high-efficiency switching amplifier. This hybrid structure has a limitation in that the maximum bandwidth is restricted by the bandwidth of the analog amplifier. Furthermore, due to the requirements for minimum time alignment, it is difficult to track envelope signals with a bandwidth of 100 MHz or more.

[0005] Accordingly, a digital ET that generates discrete power supply voltages with a step waveform has been proposed to overcome the limitations of existing analog ETs. Referring to Fig. 12, the existing digital ET has a structure in which a DC voltage is generated in advance using a pre-regulator, and then a single DC voltage level is selected using a level selection switch and connected to the RF power amplifier power supply VCC. In other words, the existing digital ET selects one of the predetermined DC voltage levels for each node and connects it to the RF power amplifier. This existing technology has the problem that as the number of digital ET waveform levels increases, the number of required capacitors also increases, leading to an increase in Bill of Material (BOM) costs.

[0006] The objective of the present invention is to solve the above problem by providing a digital envelope tracking power modulator for an RF power amplifier that outputs a multi-level voltage to the RF power amplifier by changing the connection combination of voltage sources through a switch in accordance with the envelope signal.

[0007] The objectives of the present invention are not limited to those mentioned above, and other unmentioned objectives will be clearly understood from the description below.

[0008] A digital envelope tracking power modulator for an RF power amplifier according to one aspect of the present invention for achieving the aforementioned purpose, wherein the digital envelope tracking power modulator for an RF power amplifier operates to vary the power according to the envelope of an RF signal, comprises at least two voltage sources, at least one first switch that serially connects two different voltage sources from each of the at least two voltage sources when each is turned on, and at least one second switch that provides a current path that bypasses the first switch and any one of the voltage sources connected to the first switch when the first switch is turned off.

[0009] According to the present invention, by changing the connection combination of voltage sources through a switch in accordance with the envelope signal, it has the effect of enabling the generation of many DC levels with fewer voltage sources than conventional power modulators for digital ETs.

[0010] The effects of the present invention are not limited to those mentioned above, and other unmentioned effects will be clearly understood by those skilled in the art from the description in the claims.

[0011] FIG. 1 is a circuit diagram of a digital envelope tracking power modulator for an RF power amplifier according to one embodiment of the present invention.

[0012] FIG. 2 is a diagram showing an output voltage waveform generated according to the envelope in a digital envelope tracking power modulator for an RF power amplifier according to one embodiment of the present invention.

[0013] FIG. 3 is a circuit diagram of a digital envelope tracking power modulator for an RF power amplifier according to another embodiment of the present invention.

[0014] FIG. 4 is a diagram showing the output voltage waveform generated according to the envelope in a digital envelope tracking power modulator for an RF power amplifier according to another embodiment of the present invention.

[0015] Figure 5 is a diagram showing a state including an additional voltage source for providing an offset voltage to the power modulator of Figure 3.

[0016] FIG. 6 is a circuit diagram of a digital envelope tracking power modulator for an RF power amplifier according to another embodiment of the present invention.

[0017] FIG. 7 is a diagram showing an output voltage waveform generated according to an envelope in a digital envelope tracking power modulator for an RF power amplifier according to another embodiment of the present invention of FIG. 6.

[0018] FIG. 8 is a circuit diagram of a digital envelope tracking power modulator for an RF power amplifier according to another embodiment of the present invention.

[0019] FIG. 9 is a diagram showing an output voltage waveform generated according to an envelope in a digital envelope tracking power modulator for an RF power amplifier according to another embodiment of the present invention of FIG. 8.

[0020] FIG. 10 is a diagram showing the structure of a digital envelope tracking power modulator for an RF power amplifier according to another embodiment of the present invention.

[0021] Figure 11 is a diagram showing the power modulator structure of a conventional analog ET.

[0022] Figure 12 is a diagram showing the structure of a conventional digital ET power modulator.

[0023] A digital envelope tracking power modulator for an RF power amplifier according to one aspect of the present invention for achieving the aforementioned purpose, wherein the digital envelope tracking power modulator for an RF power amplifier operates to vary the power according to the envelope of an RF signal, comprises at least two voltage sources, at least one first switch that serially connects two different voltage sources from the at least two voltage sources when each is turned on, and at least one second switch that provides a current path that bypasses the first switch and any one voltage source connected to the first switch when the first switch is turned off.

[0024] The advantages and features of the present invention, and the methods for achieving them, will become clear by referring to the embodiments described below in detail together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below but may be implemented in various different forms. These embodiments are provided merely to ensure that the disclosure of the present invention is complete and to fully inform those skilled in the art of the scope of the invention, and the present invention is defined only by the claims. Meanwhile, the terms used in this specification are for describing the embodiments and are not intended to limit the present invention. In this specification, the singular form includes the plural form unless specifically stated otherwise in the text.

[0025] The present invention relates to a digital envelope tracking power modulator for an RF power amplifier that varies the power supply according to the envelope of an RF signal and supplies a multi-level DC voltage to the RF power amplifier.

[0026] In particular, the present invention is characterized by the technical feature that it is possible to generate more DC levels with a smaller voltage source compared to conventional digital envelope tracking power modulators.

[0027] These technical features can be achieved by a configuration that changes the voltage level of a power supply output to an RF power amplifier by changing the connection combination of voltage sources through the switching operation of the first switch and the second switch, comprising at least two voltage sources each having a preset voltage level, at least one first switch that serially connects two different voltage sources from the at least two voltage sources when each is turned on, and at least one second switch provided in pair with each first switch, which provides a current path that bypasses the first switch and any one voltage source connected to the first switch when the first switch is turned off.

[0028] A digital envelope tracking power modulator for an RF power amplifier according to embodiments of the present invention will be described in detail below with reference to the attached drawings.

[0029] Referring to FIG. 1, a digital envelope tracking power modulator (100) for an RF power amplifier according to one embodiment of the present invention may include a plurality of voltage sources (101, 102, 103, 104) each having a unit voltage (1V), a plurality of first switches (111, 112, 113), and a plurality of second switches (121, 122, 123).

[0030] A plurality of voltage sources (101, 102, 103, 104) may include a 101 voltage source (101), a 102 voltage source (102), and a 103 voltage source (103), one end of which is directly connected to an RF power amplifier (PA), and a 104 voltage source (104), the other end of which is connected to ground.

[0031] A plurality of first switches (111, 112, 113) may include a first switch (111), a first switch (112), and a first switch (113).

[0032] The 111 switch (111) may connect the 101 voltage source (101) and the 102 voltage source (102) in series as one end is connected to the other end of the 101 voltage source (101) and the other end is connected to one end of the 102 voltage source (102).

[0033] The 112 switch (112) may connect the 102 voltage source (102) and the 103 voltage source (103) in series as one end is connected to the other end of the 102 voltage source (102) and the other end is connected to one end of the 103 voltage source (103).

[0034] The 113 switch (113) may connect the 103 voltage source (103) and the 104 voltage source (104) in series as one end is connected to the other end of the 103 voltage source (103) and the other end is connected to one end of the 104 voltage source (104).

[0035] A plurality of second switches (121, 122, 123) may include a first switch (121), a first switch (122), and a first switch (123).

[0036] The 121 switch (121) may be paired with the 111 switch (111) such that one end is connected to one end of the 111 switch (111) and the other end of the 101 voltage source (101), and the other end is connected to ground.

[0037] The 121 switch (121) may provide a current path that bypasses the 111 switch (111) and the 102 voltage source (102) by connecting the other end of the 101 voltage source (101) to ground as the 111 switch (111) turns on when the 111 switch (111) turns off.

[0038] The 122 switch (122) may be paired with the 112 switch (112) such that one end is connected to one end of the 112 switch (112) and the other end of the 102 voltage source (102), and the other end is connected to ground.

[0039] The 122 switch (122) may provide a current path that bypasses the 112 switch (112) and the 103 voltage source (103) by connecting the other end of the 102 voltage source (102) to ground as the 112 switch (112) turns on when the 112 switch (112) turns off.

[0040] The 123 switch (123) may be paired with the 113 switch (113), with one end connected to one end of the 113 switch (113) and the other end of the 103 voltage source (103), and the other end connected to ground.

[0041] The 123 switch (122) may provide a current path that bypasses the 113 switch (113) and the 104 voltage source (104) by connecting the other end of the 103 voltage source (103) to ground as the 113 switch (113) turns on when the 113 switch (113) turns off.

[0042] At this time, by turning off the 111 switch (111), turning on the 121 switch (121), and turning off the 112 switch (112), the 113 switch (113), the 122 switch (122), and the 123 switch (123), only the 101 voltage source (101) is connected between the RF power amplifier (PA) and ground, so that a voltage of 1V is output to the RF power amplifier (PA).

[0043] By turning on the 111 switch (111), turning off the 121 switch (121), turning off the 112 switch (112), turning on the 122 switch (122), and turning off the 113 switch (113) and the 123 switch (123), the 101 voltage source (101) and the 102 voltage source (102) can be connected between the RF power amplifier (PA) and ground, thereby allowing a voltage of 2V to be output to the RF power amplifier (PA).

[0044] By turning on the 111 switch (111), turning off the 121 switch (121), turning on the 112 switch (112), turning off the 122 switch (122), turning off the 113 switch (113), turning off the 113 switch (123), and turning on the 123 switch (123), the 101 voltage source (101), the 102 voltage source (102), and the 103 voltage source (103) are connected between the RF power amplifier (PA) and ground, so that a voltage of 3V is output to the RF power amplifier (PA).

[0045] By turning on the 111 switch (111), turning off the 121 switch (121), turning on the 112 switch (112), turning off the 122 switch (122), turning on the 113 switch (113), and turning off the 123 switch (123), the 101 voltage source (101), the 102 voltage source (102), the 103 voltage source (103), and the 104 voltage source (104) are connected between the RF power amplifier (PA) and ground, so that a voltage of 4V is output to the RF power amplifier (PA).

[0046] According to the above configuration, a digital envelope tracking power modulator (100) for an RF power amplifier according to one embodiment of the present invention has an output signal (SM) having four voltage levels corresponding to an envelope signal (Envelope) as shown in FIG. 2. OUT Can generate ).

[0047] However, one embodiment of the present invention using a single unit voltage source has a limitation in that it cannot efficiently track communication signals with a large PAPR (Peak-to-Average Power Ratio).

[0048] Specifically, 4G LTE and 5G NR signals using OFDM signals generally have a PAPR of 6 dB (DFT-s-OFDM) or 9 dB (CP-OFDM). The levels of an envelope signal with a 6 dB PAPR typically have a power spectral density of less than 50% of the peak voltage. For example, if the peak voltage of the envelope signal is 4 V, most of the envelope signal operates at 2 V or less. Therefore, to increase the efficiency of RF power amplifier power supply, fine multi-level voltage generation through non-monovoltage sources is required.

[0049]

[0050] Accordingly, in another embodiment of the present invention, fine envelope tracking is made possible by using a plurality of voltage sources that provide voltages of different preset voltage levels to generate more levels of voltage according to the connection combination of the voltage sources.

[0051] Referring to FIG. 3, a digital envelope tracking power modulator (200) for an RF power amplifier according to another embodiment of the present invention may include a plurality of voltage sources (201, 202, 203) each having a voltage of a different voltage level, a plurality of first switches (211, 212, 213), and a plurality of second switches (221, 222, 223).

[0052] A plurality of voltage sources (201, 202, 203) may include a 201 voltage source (201), a 202 voltage source (202), and a 203 voltage source (203), each having one end directly connected to an RF power amplifier (PA).

[0053] At this time, each voltage source (201, 202, 203) may provide a voltage of a different level.

[0054] Here, different voltage levels may include voltage levels that increase in multiples of 2, starting from the smallest first voltage level in order of magnitude.

[0055] For example, in the case of three voltage sources, the multiple voltage sources may each provide a voltage of any one of a first voltage level, a second voltage level which is twice the first voltage level, and a third voltage level which is twice the second voltage level.

[0056] Specifically, multiple voltage sources may each provide a voltage of multiple voltage levels calculated according to the following mathematical formula.

[0057]

[0058] (i=1, …, n)

[0059] Here, the maximum voltage value can be predetermined by the user to be greater than the peak voltage value of the envelope signal, and n represents the total number of voltage sources.

[0060] Referring to FIG. 3, the 201 voltage source (201) has a maximum voltage value of 4.9 (2 0 +2 1 +2 2 Divide by ) and 2 2 It provides a voltage of 2.8V calculated by multiplying, and the 202nd voltage source (202) provides a maximum voltage value of 4.9 (2 0 +2 1 +2 2 Divide by ) and 2 1 It provides a voltage of 1.4V calculated by multiplying, and the 203rd voltage source (203) provides a maximum voltage value of 4.9 (2 0 +2 1 +2 2 Divide by ) and 2 0 It may provide a voltage of 0.7V calculated by multiplying.

[0061] A plurality of first switches (211, 212, 213) may include a second switch (211), a second switch (212), and a second switch (213).

[0062] The 211 switch (211) may connect the 201 voltage source (201) and the 202 voltage source (202) in series as one end is connected to the other end of the 201 voltage source (201) and the other end is connected to one end of the 202 voltage source (202).

[0063] The 212 switch (212) may connect the 202 voltage source (202) and the 203 voltage source (203) in series as one end is connected to the other end of the 202 voltage source (202) and the other end is connected to one end of the 203 voltage source (203).

[0064] The 213 switch (213) may connect the other end of the 203 voltage source (203) to ground as it operates, with one end connected to the other end of the 203 voltage source (203) and the other end connected to ground.

[0065] A plurality of second switches (221, 222, 223) may include a second switch (221), a second switch (222), and a second switch (223).

[0066] The 221 switch (221) may be paired with the 211 switch (211) such that one end is connected to one end of the 201 voltage source (201) and the other end is connected to the other end of the 211 switch (211) and one end of the 202 voltage source (202).

[0067] The 221 switch (221) may provide a current path that bypasses the 201 voltage source (201) and the 211 switch (211) by connecting one end of the 201 voltage source (201) to the other end of the 211 switch (211) and one end of the 202 voltage source (202) as the 211 switch (211) turns on when the 211 switch (211) turns off.

[0068] The 222 switch (222) may be paired with the 212 switch (212) such that one end is connected to one end of the 202 voltage source (202) and the other end is connected to the other end of the 212 switch (212) and one end of the 203 voltage source (203).

[0069] The 222 switch (222) may provide a current path that bypasses the 202 voltage source (202) and the 212 switch (212) by connecting one end of the 202 voltage source (202) to the other end of the 212 switch (212) and one end of the 203 voltage source (203) as the 212 switch (212) turns on when the 212 switch (212) turns off.

[0070] The 223 switch (223) may be paired with the 213 switch (213) such that one end is connected to one end of the 203 voltage source (203) and the other end is connected to ground.

[0071] The 223 switch (223) may provide a current path that bypasses the 203 voltage source (203) and the 213 switch (213) by connecting one end of the 203 voltage source (203) to ground as the 213 switch (213) turns on when the 213 switch (213) turns off.

[0072] At this time, by turning off the 211 switch (211), turning on the 221 switch (221), turning off the 212 switch (212), turning on the 222 switch (222), turning on the 213 switch (213), and turning off the 223 switch (223), only the 203 voltage source (203) is connected between the RF power amplifier (PA) and ground, thereby allowing 0.7V according to the voltage level of the 203 voltage source (203) to be output to the RF power amplifier (PA).

[0073] By turning off the 211 switch (211), turning on the 221 switch (221), turning on the 212 switch (212), turning on the 222 switch (222), turning off the 213 switch (213), and turning on the 223 switch (223), only the 202 voltage source (202) is connected between the RF power amplifier (PA) and ground, thereby allowing 1.4V according to the voltage level of the 202 voltage source (202) to be output to the RF power amplifier (PA).

[0074] By turning off the 211 switch (211), turning on the 221 switch (221), turning on the 212 switch (212), turning on the 222 switch (222), turning off the 222 switch (222), turning off the 213 switch (213), and turning on the 223 switch (223), the 202 voltage source (202) and the 203 voltage source (203) are connected in series between the RF power amplifier (PA) and ground, thereby allowing the RF power amplifier (PA) to output 2.1V, which is the sum of the voltage levels of the 202 voltage source (202) and the 203 voltage source (203).

[0075] Specifically, in another embodiment of the present invention, a voltage source (V) connected in series between an RF power amplifier (PA) and ground according to the on or off operation of a plurality of first switches (211, 212, 213) and a plurality of second switches (221, 222, 223) is provided. con ) and the voltage output by the RF power amplifier (PA) accordingly (SM out ) is as shown in Table 1 below.

[0076] 211212213221222223V con SM OUT (V)1 Off Off Off On On On - 02 Off Off On On On Off 2030.73 Off On Off On Off On 2021.44 Off On On On Off Off 202, 2032.15 On Off Off Off On On 2012.86 On Off On Off On Off 201, 2033.57 On On Off Off Off On 201, 2024.28 On On On Off Off Off 201, 202, 2034.9

[0077] According to the above configuration, the present invention can generate a number of multi-level voltages equal to 2 squared by the number of voltage sources according to the connection combination of a plurality of voltage sources (201, 202, 203) based on the on or off operation of a plurality of first switches (211, 212, 213) and a plurality of second switches (221, 222, 223). Referring to FIG. 4, a digital envelope tracking power modulator (200) for an RF power amplifier according to another embodiment of the present invention has an output signal (SM) having 8 voltage levels corresponding to an envelope signal. OUT You can verify that it generates ).

[0078] It can be confirmed that the resolution is improved by twofold by generating four more output levels with one less voltage source compared to the digital envelope tracking power modulator for an RF power amplifier according to one embodiment of the present invention using a single unit voltage.

[0079] That is, the digital envelope tracking power modulator for an RF power amplifier according to another embodiment of the present invention tracks the envelope signal more finely than the digital envelope tracking power modulator for an RF power amplifier according to one embodiment of the present invention and can improve power efficiency.

[0080] However, the power modulator for the actual RF power amplifier must generate an offset voltage to satisfy the minimum knee voltage required for the RF power amplifier.

[0081] Accordingly, a digital envelope tracking power modulator (200) for an RF power amplifier according to another embodiment of the present invention may further include a 204 voltage source (204) for providing an offset voltage as shown in FIG. 5.

[0082] The 204th voltage source (204) can be installed between the other end of the 213th switch (213), the other end of the 223rd switch (223), and ground.

[0083] At this time, a voltage source (V) connected in series between the RF power amplifier (PA) and ground according to the on or off operation of the plurality of first switches (211, 212, 213) and the plurality of second switches (221, 222, 223) con ) and the voltage output by the RF power amplifier (PA) accordingly (SM out ) is as shown in Table 2 below.

[0084] 211212213221222223V con SM OUT (V)1 Off Off Off On On On 2040.7 2 Off Off On On On Off 203, 2041.4 3 Off On Off On Off On 202, 2042.1 4 Off On On On Off Off 202, 203, 2042.8 5 On Off Off Off On On 201, 2043.5 6 On Off On Off On Off 201, 203, 2044.2 7 On On Off Off Off On 201, 202, 2044.9 8 On On On Off Off Off 201, 202, 203, 2045.6

[0085] Meanwhile, wireless communication signals with a PAPR of 6-9 dB, which are commonly used these days, have power spectral densities that are mostly located at 1 / 2 or 1 / 4 of the peak voltage. Therefore, the performance of supply modulation can be further improved by generating discrete levels so that the supply voltage of the RF power amplifier has fine values ​​at the level with high power spectral density.

[0086] Accordingly, a digital envelope tracking power modulator for an RF power amplifier according to another embodiment of the present invention further includes an additional voltage source, one end of which is directly connected to the power amplifier, and a third switch, which connects the other end of the additional voltage source to ground according to the ON operation, thereby ensuring linearity by generating a relatively large level of voltage through the additional voltage source, while generating a fine level of voltage below half the level of the peak voltage.

[0087] Referring to FIG. 6, a digital envelope tracking power modulator (300) for an RF power amplifier according to another embodiment of the present invention may include a plurality of voltage sources (301, 302, 303) each having a voltage of a different voltage level, a plurality of first switches (311, 312, 313), a plurality of second switches (321, 322, 323), an additional voltage source (330), and a third switch (340).

[0088] A plurality of voltage sources (301, 302, 303) may include a 301 voltage source (301), a 302 voltage source (302), and a 303 voltage source (303) that are directly connected to an RF power amplifier (PA).

[0089] At this time, the 303rd voltage source (303), the 302nd voltage source (302), and the 301st voltage source (301) may each provide voltage levels of 0.35V, 0.7V, and 1.4V, which increase in multiples of 2, starting from the smallest voltage level of 0.35V in order of size.

[0090] A plurality of first switches (311, 312, 313) may include a 311 switch (311), a 312 switch (312), and a 313 switch (313).

[0091] The 311 switch (311) may connect the 301 voltage source (301) and the 302 voltage source (302) in series as one end is connected to the other end of the 301 voltage source (301) and the other end is connected to one end of the 302 voltage source (302).

[0092] The 312 switch (312) may connect the 302 voltage source (302) and the 303 voltage source (303) in series as one end is connected to the other end of the 302 voltage source (302) and the other end is connected to one end of the 303 voltage source (303).

[0093] The 313 switch (313) may connect the other end of the 303 voltage source (303) to ground as it operates, with one end connected to the other end of the 303 voltage source (303) and the other end connected to ground.

[0094] A plurality of second switches (321, 322, 323) may include a 321 switch (321), a 322 switch (322), and a 323 switch (323).

[0095] The 321 switch (321) may be paired with the 311 switch (311) such that one end is connected to one end of the 301 voltage source (301) and the other end is connected to the other end of the 311 switch (311) and one end of the 302 voltage source (302).

[0096] The 321 switch (321) may provide a current path that bypasses the 301 voltage source (301) and the 311 switch (311) by connecting one end of the 301 voltage source (301) to the other end of the 311 switch (311) and one end of the 302 voltage source (302) as the 311 switch (311) turns on when the 311 switch (311) turns off.

[0097] The 322 switch (322) may be paired with the 312 switch (312) such that one end is connected to one end of the 302 voltage source (302) and the other end is connected to the other end of the 312 switch (312) and one end of the 303 voltage source (303).

[0098] The 322 switch (322) may provide a current path that bypasses the 302 voltage source (302) and the 312 switch (312) by connecting one end of the 302 voltage source (302) to the other end of the 312 switch (312) and one end of the 303 voltage source (303) as the 312 switch (312) turns on when the 312 switch (312) turns off.

[0099] The 323 switch (323) may be paired with the 313 switch (313) such that one end is connected to one end of the 303 voltage source (303) and the other end is connected to ground.

[0100] The 323 switch (323) may provide a current path that bypasses the 303 voltage source (303) and the 313 switch (313) by connecting one end of the 303 voltage source (303) to ground as the 313 switch (313) turns on when the 313 switch (313) turns off.

[0101] An additional voltage source (330) may be directly connected to an RF power amplifier (PA) and provide a voltage level greater than the sum of the voltage levels of multiple voltage sources (301, 302, 303).

[0102] The third switch (340) may be connected to the other end of the additional voltage source (330) and connected to ground according to the operation, so that a voltage equal to the voltage level of the additional voltage source (330) is output to the RF power amplifier (PA).

[0103] In another embodiment of the present invention, a voltage source (V) connected in series between an RF power amplifier (PA) and ground according to the on or off operation of a plurality of first switches (311, 312, 313), a plurality of second switches (321, 322, 323), and a third switch (340). con ) and the voltage output by the RF power amplifier (PA) accordingly (SM out ) is as shown in Table 3 below.

[0104] 311312313321322323340V con SM OUT(V)1 Off Off Off On On On Off - 02 Off Off On On On Off Off 3030.353 Off On Off On Off On Off 3020.74 Off On On On Off Off Off 302, 3031.055 On Off Off Off On On Off 3011.46 On Off On Off On Off Off 301, 3031.757 On On Off Off Off On Off 301, 3022.18 On On On Off Off Off Off 301, 302, 3032.459 Off Off Off On On On On 3305.6

[0105] According to the above configuration, the present invention provides a large voltage level of peak voltage through an additional voltage source, but can provide a number of fine voltage levels equal to 2 squared by the number of voltage sources according to the connection combination of multiple voltage sources (201, 202, 203) at half the level of the peak voltage. Referring to FIG. 7, it can be seen that a digital envelope tracking power modulator for an RF power amplifier according to another embodiment of the present invention supports a peak level (5.6V) of an envelope signal, but generates a fine DC output level below half the level (2.8V) of the peak level.

[0106] According to another embodiment of the present invention, the envelope signal can be finely tracked below half the peak level where most of the power spectral density exists, while satisfying the linearity of the peak voltage.

[0107] Referring to FIG. 8, it can be seen that a digital envelope tracking power modulator (400) for an RF power amplifier according to another embodiment of the present invention supports a peak level (4.5V) of an envelope signal, but generates a fine DC output level above half the peak level (2.4V).

[0108] According to another embodiment of the present invention, an offset voltage required for power supply above the knee voltage of the RF power amplifier (400) is supplied, and an envelope can be finely tracked above half the peak level to generate the RMS voltage required by the system.

[0109] Meanwhile, in addition to the configuration described above, the digital envelope tracking power modulator (100, 200, 300, 400) for an RF power amplifier according to embodiments of the present invention may further include a controller (not shown) that generates a control signal for controlling the switching operation of a plurality of first switches (111~113, 211~213, 311~313, 411~413) and a plurality of second switches (121~123, 221~223, 321~323, 421~423) to track the envelope of an RF signal.

[0110] Referring to FIG. 10, a digital envelope tracking power modulator for an RF power amplifier according to another embodiment of the present invention comprises a plurality of level capacitors (C) for providing a preset level DC voltage. lv1 , C lv2 , C lv3 ), level capacitor (C lv1 , C lv2 , C lv3 It may include a level switch network (Level SW Network) comprising a plurality of first switches and second switches for connecting each voltage source, a controller (LSW Controller) that generates a control signal for turning on or off the switches included in the level switch network, output capacitor groups (Co1, Co2, Co3, Co4), first SCVB (switched-capacitor voltage balancing) switches (1st SCVB SWs), flying capacitor group A (Cf1A, Cf2A, Cf3A), flying capacitor group B (Cf1B, Cf2B, Cf3B), and second SCVB switches (2nd SCVB SWs).

[0111] According to the present invention, instead of selectively connecting any one of the voltage sources to the power amplifier through a switch, the voltage level output to the power amplifier can be changed by changing the combination of voltage sources connected to the power amplifier through the switch.

[0112] According to the present invention, a number of voltage levels equal to 2 raised to the power of the number of voltage sources can be generated according to a combination of connections of voltage sources having different levels.

[0113] In other words, it can generate more levels of voltage with a smaller voltage source compared to conventional digital ET power modulators.

[0114] Accordingly, it has the advantage of improving power efficiency by finely tracking the envelope signal.

[0115] In addition, compared to conventional digital ET power modulators for the same level, the number of capacitors required can be reduced, which can be expected to have the advantage of reducing manufacturing costs.

[0116] A person skilled in the art to which the present invention pertains will understand that the present invention may be implemented in other specific forms without altering its technical concept or essential features. Therefore, the embodiments described above should be understood as illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims set forth below rather than by the detailed description above, and all modifications or variations derived from the claims and their equivalents should be interpreted as being included within the scope of the present invention.

[0117] The present invention relates to a digital envelope tracking power modulator for an RF power amplifier.

Claims

1. A digital envelope tracking power modulator for an RF power amplifier that operates to vary the power supply according to the envelope of an RF signal, At least two voltage sources; At least one first switch that connects two different voltage sources in series from the at least two voltage sources as each turns on; and A digital envelope tracking power modulator for an RF power amplifier comprising: at least one second switch that provides a current path bypassing the first switch and any one voltage source connected to the first switch as it turns on when the first switch turns off.

2. In Paragraph 1, One of the first voltage sources among the above at least two voltage sources One is directly connected to the RF power amplifier. Digital envelope tracking power modulator for RF power amplifiers.

3. In Paragraph 2, The above first switch is One end of any one second voltage source excluding the first voltage source among the at least two voltage sources, and the other end of the other third voltage source between the second voltage source and the other third voltage source among the at least two voltage sources. Digital envelope tracking power modulator for RF power amplifiers.

4. In Paragraph 3, The above second switch is Paired with the first switch mentioned above, One end of the second voltage source and one end of the third voltage source installed Digital envelope tracking power modulator for RF power amplifiers.

5. In Paragraph 3, The above second switch is Paired with the first switch mentioned above, The one installed between the other end of the above-mentioned third voltage source and ground. Digital envelope tracking power modulator for RF power amplifiers.

6. In Paragraph 2, An additional voltage source directly connected to the RF power amplifier; and A digital envelope tracking power modulator for an RF power amplifier, further comprising a third switch installed between the additional voltage source and ground.

7. In Paragraph 1, The above at least two voltage sources Providing voltages of different voltage levels Digital envelope tracking power modulator for RF power amplifiers.

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