Amplifier circuit and envelope tracking power supply modulator

Abstract

This invention discloses an amplifier circuit, comprising: a voltage-to-current conversion circuit for generating a current signal based on an input voltage signal, wherein the voltage-to-current conversion circuit includes: an operational transconductance amplifier for outputting the current signal at its output port; and a current-to-voltage conversion circuit for generating an output voltage signal based on the current signal, wherein the current-to-voltage conversion circuit includes: a linear amplifier, wherein the input port of the linear amplifier is coupled to the output port of the operational transconductance amplifier, and the output voltage signal originates from the output signal at the output port of the linear amplifier. This invention proposes an amplifier circuit using a linear amplifier with unity-gain feedback to achieve better power efficiency.

Description

Technical Field

[0001] This invention relates to the field of circuit technology, and more particularly to an amplifier circuit and an envelope tracking power supply modulator. Background Technology

[0002] Power amplifiers (PAs) are used to amplify radio-frequency (RF) signals used for radio transmission. PAs are commonly found in wireless communication devices, driving the transmitter's antenna. PA power consumption is critical for battery-powered wireless communication devices. Traditionally, PAs are biased using a fixed supply voltage. When the RF input signal to the PA is at its maximum level, a peak RF output power condition typically occurs. However, when the PA backs off from the peak RF output power condition, the excess input power must be dissipated by the PA because it is not converted into usable RF output power. In other words, a traditional fixed PA supply voltage results in a significant amount of power loss as heat. Envelope tracking is a technique that dynamically modulates the PA's supply voltage using the envelope of the RF input signal. This allows the PA to always be closer to its peak level and significantly improves PA efficiency. In other words, envelope tracking modulates the PA supply voltage to track the envelope of the RF input signal to reduce the amount of power dissipated as heat.

[0003] In wireless communication, bandwidth is the frequency range occupied by a modulated carrier signal. With advancements in wireless communication technology, the bandwidth used by a modulated carrier signal is becoming increasingly wider. For example, bandwidth requirements in 5G New Radio (NR) applications are rapidly increasing. Therefore, envelope tracking power modulators require wide-bandwidth linear amplifiers to provide the modulated power supply voltage to the power amplifier (PA) with a peak-to-average power ratio (PAPR) output signal. However, typical linear amplifiers often consume significant quiescent current to achieve a wide envelope tracking bandwidth. Therefore, typical wideband envelope tracking designs are very power-intensive.

[0004] Therefore, an innovative amplifier design is needed that achieves wideband envelope tracking with reduced quiescent current consumption. Summary of the Invention

[0005] In view of this, the present invention provides an amplifier circuit and an envelope tracking power supply modulator to solve the above problems.

[0006] According to a first aspect of the present invention, an amplifier circuit is disclosed, comprising:

[0007] A voltage-to-current conversion circuit is used to generate a current signal based on an input voltage signal, wherein the voltage-to-current conversion circuit includes: an operational transconductance amplifier for outputting the current signal at the output port of the operational transconductance amplifier; and

[0008] A current-to-voltage conversion circuit for generating an output voltage signal based on a current signal, wherein the current-to-voltage conversion circuit includes a linear amplifier, wherein the input port of the linear amplifier is coupled to the output port of the operational transconductance amplifier, and the output voltage signal originates from the output signal of the output port of the linear amplifier.

[0009] According to a second aspect of the present invention, an envelope tracking power modulator is disclosed, comprising:

[0010] An amplifier circuit is used to receive an envelope input and generate an amplifier output based on the envelope input, wherein the amplifier output participates in setting the modulation power supply voltage of a power amplifier. The amplifier circuit includes:

[0011] A voltage-to-current conversion circuit for generating a current signal based on an envelope input, wherein the voltage-to-current conversion circuit includes: an operational transconductance amplifier for outputting the current signal at an output port of the operational transconductance amplifier; and a current-to-voltage conversion circuit for generating an amplifier output based on the current signal, wherein the current-to-voltage conversion circuit includes: a linear amplifier, wherein the input port of the linear amplifier is coupled to the output port of the operational transconductance amplifier, the output port of the linear amplifier is coupled to the power amplifier, and the amplifier outputs an output signal from the output port of the linear amplifier.

[0012] The amplifier circuit of this invention includes: a voltage-to-current conversion circuit for generating a current signal based on an input voltage signal, wherein the voltage-to-current conversion circuit includes: an operational transconductance amplifier for outputting the current signal at the output port of the operational transconductance amplifier; and a current-to-voltage conversion circuit for generating an output voltage signal based on the current signal, wherein the current-to-voltage conversion circuit includes: a linear amplifier, wherein the input port of the linear amplifier is coupled to the output port of the operational transconductance amplifier, and the output voltage signal originates from the output signal at the output port of the linear amplifier. This invention proposes an amplifier circuit using a linear amplifier with unity-gain feedback to achieve better power efficiency. Because this invention uses an operational transconductance amplifier, the feedback factor β can be made 1, which is larger than the feedback factor β of a typical design (typically less than 1, for example, 0.5), thus reducing the quiescent current of the current-to-voltage conversion circuit. Attached Figure Description

[0013] Figure 1This is a block diagram illustrating an envelope tracking supply modulator according to an embodiment of the present invention.

[0014] Figure 2 This is a diagram illustrating an amplifier circuit according to an embodiment of the present invention.

[0015] Figure 3 This is a diagram illustrating a source (degenerated amplifier) ​​according to an embodiment of the present invention.

[0016] Figure 4 The illustration shows a source degenerated amplifier with transconductance boosting according to an embodiment of the present invention.

[0017] Figure 5 This is a diagram illustrating a two-stage amplifier having at least one compensation capacitor according to an embodiment of the present invention. Detailed Implementation

[0018] In the following detailed description of embodiments of the invention, reference is made to the accompanying drawings, which form part of the invention, and which illustrate specific preferred embodiments in which the invention can be practiced. These embodiments have been described in sufficient detail to enable those skilled in the art to practice them, and it should be understood that other embodiments may be utilized, and mechanical, structural, and procedural changes may be made, without departing from the spirit and scope of the invention. Therefore, the following detailed description should not be construed as limiting, and the scope of the embodiments of the invention is defined only by the appended claims.

[0019] It will be understood that although the terms “first,” “second,” “third,” “primary,” “secondary,” etc., may be used herein to describe various elements, components, regions, layers, and / or portions, these elements, components, regions, layers, and / or portions should not be limited by these terms. These terms are used only to distinguish one element, component, region, layer, or portion from another region, layer, or portion. Therefore, without departing from the teachings of the inventive concept, the first or primary element, component, region, layer, or portion discussed below may be referred to as a second or secondary element, component, region, layer, or portion.

[0020] Furthermore, for ease of description, spatial relative terms such as “below,” “under,” “under,” “above,” and “above” may be used herein to describe the relationship of an element or feature to it. Another element or feature is shown in the figure. In addition to the orientation described in the figure, the spatial relative terms are also intended to cover different orientations of the device during use or operation. The device may be oriented in other ways (rotated 90 degrees or otherwise), and the spatial relative descriptive terms used herein may be interpreted accordingly. Additionally, it will be understood that when a layer is referred to as being “between” two layers, it may be the only layer between the two layers, or there may be one or more intermediate layers.

[0021] The terms “about,” “roughly,” and “about” generally mean a range of ±20%, ±10%, ±5%, ±3%, ±2%, ±1%, or ±0.5% of a specified value. The specified values ​​in this invention are approximate. Unless otherwise specified, the specified values ​​include the meanings of “about,” “roughly,” and “about.” The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used herein, the singular terms “a,” “an,” and “the” are also intended to include the plural forms unless the context clearly indicates otherwise.

[0022] What will be understood is that when an element or layer is referred to as being “on,” “connected to,” “coupled to,” or “adjacent to” another element or layer, it can be directly on, connected to, coupled to, or adjacent to that other element or layer, or there may be intermediate elements or layers. Conversely, when an element is referred to as being “directly on,” “directly connected to,” “directly coupled to,” or “immediately adjacent to” another element or layer, there are no intermediate elements or layers.

[0023] Note: (i) the same features will be represented by the same reference numerals throughout the figures and will not necessarily be described in detail in every figure in which they appear, and (ii) a series of figures may show different aspects of a single item, each of which is associated with various reference labels that may appear throughout the series or only in selected figures of the series.

[0024] Figure 1This is a block diagram illustrating an envelope tracking supply modulator (ETSM) according to an embodiment of the present invention. The ETSM 100 is arranged according to the envelope input S ENV Generate modulated (post-modulated) power supply voltage V PA And modulate the power supply voltage V PA This is supplied to power amplifier (PA) 101. PA 101 is modulated by the power supply voltage V. PA Power supply to amplify radio frequency (RF) signal S RF To generate an RF output PA_OUT with the desired TX power, wherein the RF output PA_OUT is transmitted into the air via antenna 102. In this embodiment, ETSM 100 employs a hybrid ETSM architecture and includes a switching converter (SWC) 104 and an amplifier circuit 106. SWC 104 is a DC-DC converter arranged via inductor L DC Generates a regulated DC voltage output V to the output port N_OUT of the ETSM 100. DC For example, SWC 104 can be implemented by a buck converter. Amplifier circuit 106 is used to receive the envelope input S. ENV And based on the envelope input S ENV Generates amplifier output (which is the output voltage signal) V AC Envelope input S ENV This originates from the transmit (TX) baseband signal generated by the modulator / demodulator (Modem) in a wireless transceiver. For example, the TX baseband signal (digital signal) is fed into an envelope tracking digital baseband circuit (which may include an envelope detection block, power scaling block, lookup table, upsampling block, etc.). The result is that the TX baseband signal is output from the envelope tracking digital baseband circuit, converted into an analog signal (voltage signal) by a digital-to-analog converter, and then processed by an analog filter to serve as the envelope input (voltage signal) S of the analog signal (voltage signal). ENV However, this is for illustrative purposes only and does not imply limitation of the invention. Since the invention focuses on amplifier design, further description of the generation of the envelope input SENV is omitted for brevity.

[0025] Amplifier circuit 106 will output V from the amplifier. AC Transmitted to the output port N_OUT of the ETSM 100. Based on the hybrid ETSM architecture, the regulated DC voltage V... DC and amplifier output V AC The modulation power supply voltage V of PA is jointly controlled PA 101. More specifically, the regulated DC voltage V DCDetermine the modulation power supply voltage V PA The DC section (i.e., the low-frequency section) of the amplifier outputs V. AC Determine the modulation power supply voltage V PA The AC section (i.e., the high-frequency section).

[0026] In this embodiment, the amplifier circuit 106 employs the proposed broadband amplifier architecture, thus using voltage-to-current conversion to achieve the unity feedback factor and input common-mode rejection of the linear amplifier. Figure 1 As shown, amplifier circuit 106 includes a voltage-to-current conversion circuit (labeled "V / I Conv") 108 and a current-to-voltage conversion circuit (labeled "I / V Conv") 110. Voltage-to-current conversion circuit 108 converts the input voltage signal (e.g., envelope input S) according to the input voltage signal (e.g., envelope input S). ENV Generate current signal I ENV The current-to-voltage conversion circuit 110 is used to convert the current signal I... ENV Generate an output voltage signal (e.g., amplifier output V). AC Output voltage signal (e.g., amplifier output V) AC The current is generated at the output port NA of the current-to-voltage conversion circuit 110, which is coupled to SWC 104 through inductor L. DC It should be noted that the current-to-voltage conversion circuit 110 is not required to convert the current signal I. ENV The input resistance is converted to the input voltage of the linear amplifier. Further details of the proposed broadband amplifier architecture are described below.

[0027] Figure 2 This is a diagram illustrating an amplifier circuit according to an embodiment of the present invention. Figure 1 The amplifier circuit 106 shown can be derived from... Figure 2 The amplifier circuit 200 shown is implemented. Figure 1 PA 101 shown can serve as the load 201 of amplifier circuit 200, wherein the load 201 can be a resistor R connected in parallel. PA and capacitor C PA Modeling, and routing inductors L through printed circuit boards (PCBs) PCBCoupled to amplifier circuit 200. Amplifier circuit 200 includes voltage-to-current conversion circuit (or voltage-to-current conversion circuit) 202 and current-to-voltage conversion circuit (or current-to-voltage conversion circuit) 204. Voltage-to-current conversion circuit 202 includes input filter bank 212 and operational transconductance amplifier (OTA) 214 with transconductance Gm. In this embodiment, the envelope input S ENV The input voltage signal of amplifier circuit 200 is a differential signal composed of a positive signal VP and a negative signal VN. Input filter bank 212 is located at the envelope input S... ENV The envelope input S is processed by OTA 214 before processing. ENV Noise filtering is applied. OTA 214 filters the envelope input S through the input filter bank 212. ENV The voltage-to-current converter generates a current signal I at output port N3. ENV , where I ENV =Gm*S ENV .

[0028] The current-to-voltage conversion circuit 204 includes a linear amplifier (LA) 216, a feedback network 218, and an optional AC coupling capacitor CAC. The input port of LA 216 may include a first input node N1 and a second input node N2, where the voltage signal V provided by the digital-to-analog converter (DAC) is... DAC The signal I is coupled to the first input node N1 and is generated by the voltage-to-current conversion circuit 202 (specifically OTA 214). ENV The input port of LA 216 (specifically, the second input node N2 of LA 216) is directly connected to the output port (second input node) N2 of OTA 214, so that LA 216 has no input resistance. Feedback network 218 is coupled between the input port of LA 216 (specifically, the second input node N2 of LA 216) and the output port N4 of LA 216, and includes at least one resistor R. FB and at least one optional capacitor C FB Resistor R FB This is a feedback resistor used to return a portion of the output signal (output voltage) LA_OUT from the output port N4 of LA 216 to the second input node N2 of LA 216. In this embodiment, the feedback resistor R... FB Network 218 further processes the current signal I ENVThe current-to-voltage conversion is implemented in the feedback network 218. Capacitor C is then used in this network. FB In the case of capacitor C FB It can be used for noise filtering. However, this does not imply a limitation of the invention. Alternatively, capacitor C can be omitted from the feedback network 218. FB .

[0029] like Figure 2 As shown, LA 216 generates an output signal LA_OUT at output port N4, where the amplifier output V of amplifier circuit 200... AC It is derived from the output signal (output voltage) LA_OUT. The AC coupling capacitor C is implemented in the current-to-voltage conversion circuit 204. AC In this case, the amplifier output V AC This is achieved by connecting the output signal LA_OUT through an AC coupling capacitor C. AC And obtained. AC coupling capacitor C AC The output signal LA_OUT can be DC smoothed, allowing LA 216 to operate at a lower voltage range to further reduce quiescent current. However, this does not imply limitation of the invention. In some embodiments of the invention, the AC coupling capacitor C of the current-to-voltage conversion circuit 204 may be omitted. AC The output signal LA_OUT can be directly used as the amplifier output V. AC .

[0030] Due to the inherent characteristics of the OTA 214, the output impedance R of the OTA 214 is... OUT (That is, the impedance (or resistance) of OTA 214 as viewed from the current-to-voltage conversion circuit 204) is very large. Therefore, the feedback factor β of the feedback network 218 can be considered to have a value equal to 1. In other words, due to the large output impedance ROUT of the OTA, the feedback network 218 can have a unit feedback factor (β = 1). The feedback factor β of the feedback network 218 can be expressed by the following formula.

[0031] Where R OUT >>R FB (1)

[0032] Compared to traditional LA designs with a feedback factor β less than 1, operational amplifiers require greater quiescent current to achieve higher open-loop gain to meet the target closed-loop gain requirement. To address this issue, this invention proposes using an operational amplifier with a large output impedance R... OUTThe voltage-to-current conversion circuit 202 is used to make the feedback factor β equal to 1, thus allowing the LA216 to meet the same target closed-loop gain requirement with lower quiescent current consumption. In other words, this invention proposes an amplifier circuit using an LA with unity-gain feedback to achieve better power efficiency. Because this invention uses OTA to achieve a feedback factor β of 1, which is larger than the feedback factor β of a typical design (typically less than 1, for example 0.5), the quiescent current of the current-to-voltage conversion circuit 204 can be reduced.

[0033] As mentioned above, the amplifier output V AC The AC portion (i.e., the high-frequency portion) of the modulation supply voltage VPA is determined. Therefore, conventional LA designs may be affected by input common-mode (CM) oscillations due to envelope tracking oscillations at the modulation supply voltage VPA, which are fed back to the LA's voltage input. To address this issue, this invention proposes using a voltage-to-current conversion circuit 202 to provide a current-mode input to the LA 216 instead of a voltage-mode input, where the current signal I... ENV Unaffected by envelope tracking oscillations in modulated power supply voltage V PA In short, the voltage-to-current conversion circuit 202 provides input CM suppression in current mode, thus ensuring a small CM voltage swing for LA 216. Because LA 216 has a fixed CM voltage level at its input, it can improve linearity and reduce quiescent current consumption.

[0034] The closed-loop gain G of amplifier circuit 200 can be expressed by the following formula.

[0035]

[0036] Due to the feedback resistor R FB The resistance value is fixed, and the variation of the transconductance Gm provided by the OTA 214 will affect the stability of the closed-loop gain G. In order to achieve a stable transconductance Gm, this invention proposes to use a source degenerated amplifier. Figure 3 This is a schematic diagram of a source degradation amplifier according to an embodiment of the present invention. Figure 2 The OTA 214 shown can be... Figure 3 The source degradation amplifier 300 shown is implemented. For simplicity, Figure 3Only a portion of the source-degraded amplifier 300 is shown. The source-degraded amplifier 300 includes a differential pair with source degradation, wherein the differential pair consists of two P-channel metal-oxide-semiconductor (PMOS) transistors MP1 and MP2. The source terminal of PMOS transistor MP1 is connected in series with one end of resistor R1 (R1 = Rdeg), and the source terminal of PMOS transistor MP2 is connected in series with one end of resistor R2 (R2 = Rdeg). The other ends of resistors R1 and R2 are both coupled to the power supply voltage VDD through a current source 302. The transconductance Gm of the source-degraded amplifier 300 can be expressed using the following formula.

[0037]

[0038] In equation (3) above, g m This represents the transconductance of each PMOS transistor MP1 / MP2. If g m and R deg One or two of them are appropriately set to g m ·R deg If >>1, then the transconductance Gm of the source degenerate amplifier 300 can be expressed by the following formula.

[0039] Where g m ·R deg >>1, of which (4)

[0040] Therefore, in which g m ·R deg Under the condition that >>1, the closed-loop gain G of amplifier circuit 200 can be expressed by the following formula.

[0041]

[0042] Since the closed-loop gain G is determined by the ratio of the resistance of the feedback resistor to the resistance of the source degradation resistor, the closed-loop gain G is a fixed value regardless of the operation of amplifier circuit 200.

[0043] In some embodiments of the present invention, transconductance enhancement techniques may be employed to ensure that the conditions are met. Figure 4 This is a diagram illustrating a source degradation amplifier with transconductance boosting according to an embodiment of the present invention. Figure 2 The OTA 214 shown can be... Figure 4The source-degradation amplifier 400 shown is implemented. The source-degradation amplifier 400 includes PMOS transistors MP1 and MP2, NMOS transistors MN1 and MN2, amplifiers A1 and A2, resistors R1 and R2, and a current source 402. The source-negative feedback amplifier 400 has a differential pair with source-negative feedback, consisting of two NMOS transistors MN1 and MN2. One end of the source-end series resistor R1 (R1 = Rdeg) of NMOS transistor MN1, and one end of the source-end series resistor R2 (R2 = Rdeg) of NMOS transistor MN2, are connected to ground voltage GND via the current source 402. Specifically, amplifier A1 is used to increase the transconductance of NMOS transistor MN1, and amplifier A2 is used to increase the transconductance of NMOS transistor MN2.

[0044] With the advancement of wireless communication technology, the bandwidth used by a modulated carrier signal is becoming increasingly wider. For example, the bandwidth requirements in 5G New Radio (NR) applications are rapidly increasing. Therefore, envelope tracking power modulators require wide-bandwidth linear amplifiers to provide the modulated power supply voltage to the power amplifier. When using amplifier circuit 200 with a source negative feedback amplifier having transconductance boost for broadband applications, the present invention further proposes using a two-stage amplifier with at least one compensation capacitor as a transconductance boost amplifier (e.g., amplifiers A1 or A2 shown in the diagram). Figure 4 This is to ensure that the conditions are still met at higher frequencies. In prior art, the voltage signal (e.g., envelope input (voltage signal) S) is typically directly applied. ENV Converted to modulated power supply voltage V PA For example, voltage-to-voltage conversion can be performed directly using components such as voltage converters. In prior art circuits, the feedback factor β is less than 1, requiring the operational amplifier to consume a larger quiescent current to achieve a larger open-loop gain to meet the target closed-loop gain requirement. In this invention, such as... Figure 1 As shown, this invention adds a voltage-to-current conversion circuit 108 and a current-to-voltage conversion circuit 110, that is, first converting the envelope input (voltage signal) S... ENV Converted to current signal I ENV Then the current signal I ENV Converted to amplifier output (output voltage signal) V AC This leads to the modulation power supply voltage V. PA The solution of this invention makes the circuit feedback factor β equal to 1, thus allowing the LA 216 to meet the same target closed-loop gain requirement with lower quiescent current consumption. Furthermore, in the prior art, a resistor is placed between the filter and the linear amplifier. In this invention, however, as... Figure 2As shown, this invention adds an OTA214 between the input filter bank 212 and the second input node N2 of LA 216 for broadband applications. Furthermore, this invention eliminates the resistor found in the prior art (i.e., there is no resistor between OTA 214 and the second input node N2 of LA 216; they are directly connected), therefore the output impedance R of OTA 214 is... OUT The feedback factor β of the feedback network 218 is very large. Therefore, the feedback factor β of the feedback network 218 is equal to 1. This reduces the bandwidth requirement to achieve the same frequency, reduces the bandwidth requirement of the linear amplifier, and reduces the power consumption of the linear amplifier.

[0045] Figure 5 This is a diagram illustrating a two-stage amplifier with at least one compensation capacitor according to an embodiment of the present invention. Figure 4 Each of the amplifiers A1 and A2 shown can be generated by Figure 5 The two-stage amplifier 500 shown is implemented. The two-stage amplifier 500 receives the input voltage V. INN and V INP And generate an output voltage V OUTP To transconductance boost target (e.g., Figure 4 The NMOS transistor MN1 or MN2 shown is illustrated. Figure 5 As shown, the two-stage amplifier 500 includes PMOS transistors MP1, MP2, MP3, NMOS transistors MN1, MN2, MN3, resistor R, current source 502, and Miller compensation capacitor C. M and feedforward compensation capacitor C FF Miller compensation capacitor C M and / or feedforward compensation capacitor C FF The use of this method can guarantee the transconductance g of NMOS transistors MN1 / MN2 m The performance is still improved at higher frequencies. In this embodiment, the Miller compensation capacitor C M and feedforward compensation capacitor C FF All of these are implemented in the two-stage amplifier 500. However, this is for illustrative purposes only and does not imply limitation of the invention. In an alternative design, the two-stage amplifier 500 can be modified to omit the feedforward compensation capacitor C. FF In another alternative design, the two-stage amplifier 500 can be modified to omit the Miller compensation capacitor C. M .

[0046] Those skilled in the art will readily observe that numerous modifications and alterations can be made to the apparatus and method while maintaining the teachings of this invention. Therefore, the foregoing disclosure should be interpreted as being limited only by the scope and limits of the appended claims.

Claims

1. An amplifier circuit, characterized in that, include: A voltage-to-current conversion circuit for generating a current signal based on an input voltage signal, wherein the voltage-to-current conversion circuit includes: an operational transconductance amplifier for outputting the current signal at its output port; and... A current-to-voltage conversion circuit for generating an output voltage signal based on a current signal, wherein the current-to-voltage conversion circuit includes: a linear amplifier, wherein the input port of the linear amplifier is coupled to the output port of the operational transconductance amplifier, and the output voltage signal originates from the output signal of the output port of the linear amplifier; The current-to-voltage conversion circuit also includes: A feedback resistor is connected between the input and output ports of the linear amplifier. This operational transconductance amplifier is a source-degraded amplifier with transconductance boost, and the ratio of the output voltage signal to the input voltage signal, or the closed-loop gain G of the amplifier circuit, is determined by the resistance R of the feedback resistor. FB With the source-degraded amplifier's resistor R deg The ratio is determined, i.e., G=R FB / R deg .

2. The amplifier circuit as described in claim 1, characterized in that, There is no input resistor connected between the input port of the linear amplifier and the output port of the operational transconductance amplifier.

3. The amplifier circuit as described in claim 1, characterized in that, This source-degraded amplifier includes differential pairs with source degrade.

4. The amplifier circuit as described in claim 3, characterized in that, Each of these amplifiers is a two-stage amplifier with at least one compensation capacitor.

5. The amplifier circuit as described in claim 4, characterized in that, The differential pair includes a first transistor and a second transistor, and the source degradation amplifier also includes a first differential amplifier and a second differential amplifier; In this configuration, the first input terminal of the first differential amplifier is coupled to a negative signal, the second input terminal is directly connected to the source of the first transistor, and the output terminal is directly connected to the gate of the first transistor; the first input terminal of the second differential amplifier is coupled to a positive signal, the second input terminal is directly connected to the source of the second transistor, and the output terminal is directly connected to the gate of the second transistor. Both the first differential amplifier and the second differential amplifier are two-stage amplifiers with at least one compensation capacitor.

6. The amplifier circuit as described in claim 1, characterized in that, The current-to-voltage conversion circuit also includes: Feedback network, including the feedback resistor; The feedback network also includes: At least one capacitor is coupled between the input and output ports of the linear amplifier to filter out noise.

7. The amplifier circuit as described in claim 6, characterized in that, This feedback network has a unit feedback factor.

8. The amplifier circuit as described in claim 1, characterized in that, The current-to-voltage conversion circuit also includes: An AC coupling capacitor is connected to the output terminal of the linear amplifier to generate the output voltage signal based on the output signal of the linear amplifier.

9. The amplifier circuit as described in claim 1, characterized in that, The output voltage signal is generated at the output port of the current-to-voltage conversion circuit, which is coupled to the switching converter through an inductor.

10. An envelope tracking power supply modulator, characterized in that, include: An amplifier circuit is used to receive an envelope input and generate an amplifier output based on the envelope input, wherein the amplifier output participates in setting the modulation power supply voltage of a power amplifier. The amplifier circuit includes: A voltage-to-current conversion circuit for generating a current signal based on an envelope input, wherein the voltage-to-current conversion circuit includes: an operational transconductance amplifier for outputting the current signal at the output port of the operational transconductance amplifier; and a current-to-voltage conversion circuit for generating an amplifier output based on the current signal, wherein the current-to-voltage conversion circuit includes: a linear amplifier, wherein the input port of the linear amplifier is coupled to the output port of the operational transconductance amplifier, the output port of the linear amplifier is coupled to the power amplifier, and the amplifier outputs an output signal from the output port of the linear amplifier; The current-to-voltage conversion circuit also includes: A feedback resistor is connected between the input and output ports of the linear amplifier. This operational transconductance amplifier is a source-degraded amplifier with transconductance boost. The closed-loop gain G of this amplifier circuit is determined by the resistance R of the feedback resistor. FB With the source-degraded amplifier's resistor R deg The ratio is determined, i.e., G=R FB / R deg .

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