Active negative feedback circuit and power amplifier
By connecting an active device in parallel in the active negative feedback circuit and using the gate-source capacitance to compensate for the gate-drain capacitance, the problem of reduced linearity and efficiency of transistors under large-signal conditions is solved, achieving high linearity and high efficiency in the saturation region.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- DYNAX SEMICON
- Filing Date
- 2025-11-17
- Publication Date
- 2026-05-01
AI Technical Summary
In existing technologies for radio frequency applications, it is difficult to maintain the linearity of transistors under large signal operating conditions, especially when the gate-drain capacitance changes significantly in saturation, leading to a decrease in linearity and efficiency.
An active negative feedback circuit is adopted, which connects the first and second active devices in parallel. The gate-source capacitance of the first active device is used to compensate the gate-drain capacitance of the second active device, keeping the capacitance constant when the input power changes, thereby improving linearity.
Under large-signal operating conditions, it improves the linearity of transistors, enhances AMAM&M performance, reduces gate-drain capacitance variation, and improves the overall linearity and efficiency of the circuit.
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Figure CN121966468A_ABST
Abstract
Description
Active negative feedback circuit and power amplifier Technical Field
[0001] This invention relates to the field of microelectronics technology, and more particularly to an active negative feedback circuit and a power amplifier. Background Technology
[0002] With the development of microelectronics technology and wireless communication base stations and other equipment, the quality requirements for transmitted signals are increasing. This necessitates that, in addition to focusing on the output power and efficiency of power amplifiers, radio frequency applications must also pay close attention to the linearity of transistors under power amplifier operating conditions. Summary of the Invention
[0003] This invention provides an active negative feedback circuit and a power amplifier to improve circuit linearity.
[0004] According to one aspect of the present invention, an active negative feedback circuit is provided, comprising:
[0005] A coupler is provided, wherein an RF input signal is received at its input terminal, and the RF input signal is divided into a feedback signal and a main signal; wherein the feedback signal is output from the first output terminal of the coupler, and the main signal is output from the second output terminal of the coupler.
[0006] The first active device, wherein the gate of the first active device is coupled to the first output terminal of the coupler;
[0007] The second active device has its gate coupled to the second output terminal of the coupler; the drain of the second active device is coupled to the source of the first active device.
[0008] The gate of the first active device is also connected to a first gate power supply voltage, and the drain of the first active device is connected to a first drain power supply voltage.
[0009] The gate of the second active device is also connected to a second gate power supply voltage, and the drain of the second active device is also connected to a second drain power supply voltage. The drain of the second active device outputs an RF output signal.
[0010] Optionally, the size of the first active device is smaller than the size of the second active device.
[0011] Optionally, the ratio of the gate-drain capacitance to the gate-source capacitance of the first active device is a first set value; and the ratio of the gate-drain capacitance to the gate-source capacitance of the second active device is a first set value.
[0012] The ratio of the gate width of the first active device to the gate width of the second active device is less than the first set value.
[0013] Optionally, the ratio of the size of the first active device to the size of the second active device is a second set value;
[0014] The coupler is configured such that the ratio of the feedback signal output from its first output terminal to the main signal output from its second output terminal is the second set value.
[0015] Optionally, the active negative feedback circuit also includes:
[0016] A phase conversion module is connected between the source of the first active device and the drain of the second active device to compensate for the phase difference between the first active device and the second active device.
[0017] Optionally, the phase conversion module includes a 50-ohm λ / 4 transmission line.
[0018] Optionally, the first drain supply voltage is twice the second drain supply voltage;
[0019] The first gate supply voltage is the sum of the gate-source voltage of the first active device and the second drain supply voltage.
[0020] Optionally, the active negative feedback circuit also includes:
[0021] A radio frequency input module, wherein the coupler is coupled to the radio frequency input signal through the radio frequency input module;
[0022] The radio frequency output module outputs the radio frequency output signal through the drain of the second active device.
[0023] Optionally, the active negative feedback circuit also includes:
[0024] The first gate DC power supply arm, the gate of the first active device is coupled to the first gate power supply voltage through the first gate DC power supply arm;
[0025] The first drain DC power supply arm, the drain of the first active device is coupled to the first drain power supply voltage through the first drain DC power supply arm;
[0026] The gate of the second active device is coupled to the second gate supply voltage through the second gate DC power supply arm.
[0027] The drain of the second active device is coupled to the drain supply voltage through the second drain DC power supply arm.
[0028] Optionally, the first active device includes a GaN HEMT device; and the second active device includes a GaNHEMT device.
[0029] According to another aspect of the present invention, a power amplifier is provided, comprising: an active negative feedback circuit as described in any embodiment of the present invention.
[0030] In this embodiment of the invention, the gate-source of the first active device and the gate-drain of the second active device are connected in parallel. The gate-source capacitance Cgs1 is between the gate and source of the first active device, and the gate-drain capacitance Cgd2 is between the gate and drain of the second active device. After parallel connection, the gate-drain capacitance Cgd of the second active device becomes the sum of the gate-source capacitance Cgs1 and the gate-drain capacitance Cgd2. The gate-source capacitance Cgs1 of the first active device is used to compensate for the gate-drain capacitance Cgd2 of the second active device. Because the gate-source capacitance Cgs1 and the gate-drain capacitance Cgd2 can achieve dynamic balance, the compensated gate-drain capacitance Cgd of the second active device can remain as constant as possible as the input power Pin increases. That is, this embodiment of the invention is advantageous because, under large-signal operating conditions, the change in the gate-drain capacitance Cgd of the second active device is small throughout the linear region to the saturation region, thereby improving the linearity of the entire circuit and improving the AMAM&M performance.
[0031] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of the present invention, nor is it intended to limit the scope of the invention. Other features of the invention will become readily apparent from the following description. Attached Figure Description
[0032] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0033] Figure 1 is a schematic diagram of the formation of intrinsic capacitance by a common source structure of a GaN HEMT device according to an embodiment of the present invention;
[0034] Figure 2 is a schematic diagram of an active negative feedback circuit provided in an embodiment of the present invention;
[0035] Figure 3 is a schematic diagram of another active negative feedback circuit provided in an embodiment of the present invention;
[0036] Figure 4 is a schematic diagram of another active negative feedback circuit provided in an embodiment of the present invention;
[0037] Figure 5 is a schematic diagram of another active negative feedback circuit provided in an embodiment of the present invention. Detailed Implementation
[0038] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.
[0039] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.
[0040] To better understand the technical solutions provided in the embodiments of this invention, the linearity of a gallium nitride high electron mobility transistor (GaN HEMT) is explained below using this example. Research shows that GaN HEMT devices typically operate under large-signal conditions, and the sources of their nonlinearity can be determined by two core static indices: AMAM and AMPM. AMAM stands for Amplitude-to-Amplitude, representing the compression or expansion of the output envelope amplitude when the input signal envelope (AM) is plotted on the x-axis. AMPM, on the other hand, represents the offset of the output carrier phase relative to the ideal phase when the input envelope amplitude is plotted on the x-axis. The changes in AMAM and AMPM parameters are mainly due to the variation of the gate-drain capacitance Cgd of the transistor device with the input power. Regarding the variation of the gate-drain capacitance Cgd with input power, related technologies have improved methods at the transistor device level, such as increasing the device's gm (transconductance) flatness to reduce the influence of Miller capacitance on the input and output terminals; or improving gate control capability by adopting structures such as fin gates. However, these methods can only improve the linearity of transistor devices operating in the linear and weakly nonlinear regions. When operating in the saturation state, i.e. the strong nonlinear region, the effect of suppressing the change of gate-drain capacitance Cgd is poor.
[0041] Figure 1 is a schematic diagram illustrating the formation of intrinsic capacitance in a common-source structure of a GaN HEMT device according to an embodiment of the present invention. Referring to Figure 1, the gate-source capacitance Cgs is formed by a parallel-plate capacitor with the two-dimensional electron gas (2DEG) near the source as the lower plate and the sidewall and lower side of the gate as the upper plate. The gate-drain capacitance Cgd is formed by the two-dimensional electron gas (2DEG) near the drain as the lower plate, and the sidewall and gate as the lower plate. Changes in the gate voltage Vgs and drain voltage Vds affect the depletion region and the two-dimensional electron gas (2DEG), thus influencing the magnitudes of the gate-source capacitance Cgs and the gate-drain capacitance Cgd. Studies have shown that regardless of changes in the gate voltage Vgs and drain voltage Vds, the LDS (source-drain distance) of the GaN HEMT device is fixed. Therefore, the gate-source capacitance Cgs and the gate-drain capacitance Cgd can be considered to be in a dynamic competitive relationship as the gate voltage Vgs and drain voltage Vds change. When the gate voltage Vgs increases and the drain voltage Vds remains constant, the gate-source capacitance Cgs increases while the gate-drain capacitance Cgd decreases. In this case, the GaNHEMT device exhibits strong gate control over the channel. Further increasing the gate voltage Vgs weakens this control, causing the gate-source capacitance Cgs to decrease while the gate-drain capacitance Cgd increases. When the drain voltage Vds is too high, the threshold voltage becomes even lower, further weakening the gate's control over the channel—a phenomenon known as DIBL (Drain-Induced Barrier Lowering) effect.
[0042] Throughout the entire transition, the sum of the gate-source capacitance Cgs and the gate-drain capacitance Cgd changes relatively little. The change in the sum of these two capacitances is primarily influenced by the capacitance formed by the gate sidewall and the two-dimensional electron gas (2DEG), while the sum of the capacitance formed by the gate bottom wall and the 2DEG remains essentially constant. Furthermore, the capacitance formed by the gate bottom wall and the 2DEG typically accounts for over 90% of the total capacitance. Therefore, it can be approximated that the sum of the gate-source capacitance Cgs and the gate-drain capacitance Cgd remains essentially constant as the GaN HEMT device transitions from the linear region to the saturation region.
[0043] Based on the above research, this invention provides an active negative feedback circuit. Figure 2 is a schematic diagram of an active negative feedback circuit provided in this invention. Referring to Figure 2, the active negative feedback circuit includes:
[0044] Coupler 10 is connected to the input terminal of the radio frequency input signal RF_in, and the radio frequency input signal RF_in is divided into a feedback signal and a main signal; wherein, the feedback signal is output from the first output terminal 11 of the coupler 10, and the main signal is output from the second output terminal 12 of the coupler 10.
[0045] The first active device PA1 has its gate g coupled to the first output terminal 11 of the coupler 10.
[0046] The second active device PA2 has its gate g coupled to the second output terminal 12 of the coupler 10; the drain d of the second active device PA2 is coupled to the source s of the first active device PA1.
[0047] The gate g of the first active device PA1 is also connected to the first gate power supply voltage Vg1, and the drain d of the first active device PA1 is connected to the first drain power supply voltage Vd1.
[0048] The gate g of the second active device PA2 is also connected to the second gate supply voltage Vg2, and the drain d of the second active device PA2 is also connected to the second drain supply voltage Vd2. The RF output signal RF_out is output from the drain d of the second active device PA2.
[0049] In this configuration, the RF output signal RF_out from the drain d of the second active device PA2 is output through the RF output module 40. A constant signal, such as ground, is connected to the source s of the second active device PA2 to achieve a source-to-ground MS structure. The source s of the first active device PA1 is coupled to the drain d of the second active device PA2, forming a CPW structure. Furthermore, the gate-source of the first active device PA1 and the gate-drain of the second active device PA2 are connected in parallel. The gate-source capacitance Cgs1 is between the gate and source of the first active device PA1, and the gate-drain capacitance Cgd2 is between the gate and drain of the second active device PA2. After parallel connection, the gate-drain capacitance Cgd of the second active device PA2 becomes the sum of the gate-source capacitance Cgs1 and the gate-drain capacitance Cgd2. The gate-source capacitance Cgs1 of the first active device PA1 is used to compensate for the gate-drain capacitance Cgd2 of the second active device PA2. Because the gate-source capacitance Cgs1 and the gate-drain capacitance Cgd2 can achieve dynamic balance, the compensated gate-drain capacitance Cgd of the second active device PA2 can remain as constant as possible as the input power Pin increases. That is, this embodiment of the invention achieves negative feedback compensation of the second active device PA2 based on the first active device PA1. This is beneficial because, under large-signal operating conditions, the change in the gate-drain capacitance Cgd of the second active device PA2 is small throughout the linear region to the saturation region, thereby improving the linearity of the entire circuit and improving the AMAM&M index.
[0050] Based on the above embodiments, optionally, the circuit performance can be further optimized by adjusting the dimensions of the first active device PA1 and the second active device PA2. Specifically, the size of the first active device PA1 is smaller than the size of the second active device PA2. Increasing the gate-drain capacitance Cgd of the second active device PA2 reduces the overall circuit gain, and in the parallel structure provided by this embodiment, the first active device PA1 only acts as negative feedback and does not actually contribute to the RF output signal RF_out, thus degrading the overall circuit efficiency. Reducing the size of the first active device PA1 helps maintain a high level of overall circuit efficiency. Furthermore, setting the size of the first active device PA1 to be smaller than the size of the second active device PA2 also allows the first active device PA1 to better compensate for the gate-drain capacitance Cgd of the second active device PA2.
[0051] Based on the above embodiments, optionally, the ratio of the gate-drain capacitance Cgd1 to the gate-source capacitance Cgs1 of the first active device PA1 is a first set value α; and the ratio of the gate-drain capacitance Cgd2 to the gate-source capacitance Cgs2 of the second active device PA2 is a first set value α; the ratio of the gate width Width1 of the first active device PA1 to the gate width Width2 of the second active device PA2 is less than the first set value α. That is, Cgd1 / Cgs1=α, Cgd2 / Cgs2=α, Width1 / Width2<α. Preferably, Cgd1 / Cgs1=α, Cgd2 / Cgs2=α, Width1 / Width2=α.
[0052] The first set value α is set based on the premise that the first active device PA1 and the second active device PA2 have high gains. Preferably, α < 1 / 5 to reduce the impact of the first active device PA1 on circuit efficiency. For the die of the active device on a fixed platform, its gate length, gate-drain pitch, and source-drain pitch are fixed. By setting the gate width of the active device, the overall size of the active device can be determined. Once the size of the active device is determined, for a fixed application, its application bias Vd (including the first drain supply voltage Vd1 and the second drain supply voltage Vd2) is fixed. Therefore, in the small-signal state, the ratio of the gate-source capacitance Cgs to the gate-drain capacitance Cgd of the active devices (including the first active device PA1 and the second active device PA2) can be determined.
[0053] For example, in one application, Vd is 28V, and the first set value α is set to α < 1 / 10. Correspondingly, the gate width Width1 of the first active device PA1 and the gate width Width2 of the second active device PA2 need to satisfy Width1 / Width2 < 1 / 10. In this embodiment of the invention, the gate-source capacitance Cgs1 of the first active device PA1 is used to compensate the gate-drain capacitance Cdg2 of the second active device PA2. Assuming Width1 / Width2 = 1 / 10, then Cgd1 / Cgd2 = 1 / 10, i.e., Cgd2 = 10Cgd1; simultaneously, Cgd1 / Cgs1 = 1 / 10, i.e., Cgs2 = 10Cgd1; at this time, Cgd2 = Cgs2. Therefore, it can be seen that the gate-source capacitance Cgs1 of the first active device PA1 and the gate-drain capacitance Cdg2 of the second active device PA2 are in the same capacitance class. The gate-source capacitance Cgs1 of the first active device PA1 can effectively compensate for the gate-drain capacitance Cdg2 of the second active device PA2.
[0054] In practical applications, the size of the first active device PA1 depends on the balance between gain (or efficiency) and linearity of the entire circuit. A smaller PA1 size can achieve greater gain and efficiency, but reduces feedback compensation and linearity. Conversely, a larger PA1 size can improve feedback compensation, but at the expense of gain and efficiency. Therefore, adjustments can be made as needed in practical applications.
[0055] It should be noted that the above analysis assumes implementation under small-signal conditions, while the embodiments of the present invention are mainly applied to large-signal conditions. However, it is understood that the feedback compensation of the first active device PA1 to the second active device PA2 under small-signal conditions is an ideal state. Under large-signal conditions, the first active device PA1 can also provide feedback compensation to the second active device PA2.
[0056] Based on the above embodiments, optionally, the ratio of the size of the first active device PA1 to the size of the second active device PA2 is a second set value β; the coupler 10 is configured such that the ratio of the feedback signal output from its first output terminal 11 to the main signal output from its second output terminal 12 is a second set value β.
[0057] The coupler 10 is configured to match the dimensions of the first active device PA1 and the second active device PA2. For example, the gate width Width represents the size of the active device, and Width1 / Width2 = β. The power distribution of the coupler 10 is determined by the gate width Wdith1 of the first active device PA1 and the gate width Width2 of the second active device PA2; that is, the power distribution ratio of the coupler 10 is also β. With this configuration, given an input power Pin, the power allocated to the branch containing the first active device PA1 is Pin × Wdith1 / (Wdith1 + Wdith2), and the power allocated to the branch containing the second active device PA2 is Pin × Wdith2 / (Wdith1 + Wdith2). This configuration helps ensure that the first active device PA1 and the second active device PA2 remain in the same operating state, thereby enabling the gate-source capacitance Cgs1 of the first active device PA1 to accurately compensate for the change in the gate-drain capacitance Cgd2 of the second active device PA2 throughout the entire operating range, achieving a dynamic balance effect.
[0058] Figure 3 is a schematic diagram of another active negative feedback circuit provided in an embodiment of the present invention. Referring to Figure 3, based on the above embodiments, the active negative feedback circuit optionally further includes: a phase conversion module 20, which is connected between the source s of the first active device PA1 and the drain d of the second active device PA2 to compensate for the phase difference between the first active device PA1 and the second active device PA2. Since the RF input signal RF_in is split into two paths, the two signals will have different phase changes when passing through different transmission lines (with inductance), thus generating a phase difference; and the drain d of the second active device PA2 will have an output capacitor, which will also generate a certain phase change. By setting the phase conversion module 20, the phase of the source s of the first active device PA1 is corrected, thereby improving the feedback compensation effect.
[0059] Furthermore, the phase conversion module 20 includes a 50-ohm λ / 4 transmission line MS1. The λ / 4 transmission line is a section of transmission line with a length equal to one-quarter of the operating wavelength. In practical applications, different phase conversion angles can be achieved by setting the length of this transmission line. Its circuit structure is simple and easy to implement.
[0060] It should be noted that in other embodiments, the phase transformation module 20 may be configured to use other circuit structures; in other embodiments, the active negative feedback circuit may be configured without the phase transformation module 20.
[0061] Based on the above embodiments, optionally, the first drain supply voltage Vd1 is twice the second drain supply voltage Vd2; the first gate supply voltage Vg1 is the sum of the gate-source voltage Vgs1 of the first active device PA1 and the second drain supply voltage Vd2. That is, Vd1 = 2Vd2, Vg1 = Vd2 + Vgs1. The second drain supply voltage Vd2 is selected according to the application requirements. The source (s) of the first active device PA1 is connected to the drain (d) of PA2. The overall voltage level of the first active device PA1 is one level higher than that of the second active device PA2. Therefore, the drain supply voltage Vd1 is set to Vd1 = 2Vd2. This setting facilitates the normal operation of the first active device PA1 and ensures that the first active device PA1 and the second active device PA2 are in the same operating state, thereby achieving a better feedback compensation effect.
[0062] Figure 4 is a schematic diagram of another active negative feedback circuit provided in an embodiment of the present invention. Referring to Figure 4, based on the above embodiments, the active negative feedback circuit may optionally further include:
[0063] The RF input module 30 and the coupler 10 are coupled to the RF input signal RF_in through the RF input module 30.
[0064] The RF output module 40 outputs the RF output signal RF_out through the drain d of the second active device PA2.
[0065] The RF input module 30 couples the RF input signal RF_in to the input terminal of the coupler 10, filtering out other signals; the RF output module 40 couples the RF output signal RF_out to the output terminal, filtering out other signals. For example, the RF input module 30 includes a first capacitor C1, and the RF output module 40 includes a second capacitor C2. The capacitors block DC and pass AC signals, thus filtering the RF signal. In other embodiments, the RF input module 30 and / or the RF output module 40 may also have impedance matching functionality.
[0066] Figure 5 is a schematic diagram of another active negative feedback circuit provided in an embodiment of the present invention. Referring to Figure 5, based on the above embodiments, the active negative feedback circuit may optionally further include:
[0067] The first gate DC power supply arm 50, the gate g of the first active device PA1 is coupled to the first gate power supply voltage Vg1 through the first gate DC power supply arm 50;
[0068] The first drain DC power supply arm 60, the drain d of the first active device PA1 is coupled to the first drain power supply voltage Vd1 through the first drain DC power supply arm 60;
[0069] The second gate DC power supply arm 70, the gate g of the second active device PA2 is coupled to the second gate power supply voltage Vg2 through the second gate DC power supply arm 70;
[0070] The second drain DC power supply arm 80 is used to couple the drain d of the second active device PA2 to the second drain power supply voltage Vd2.
[0071] The first gate DC power supply arm 50, the first drain DC power supply arm 60, the second gate DC power supply arm 70, and the second drain DC power supply arm 80 are used to isolate radio frequency (RF) signals and prevent RF signals from interfering with the DC power supply. For example, the first gate DC power supply arm 50 includes a first inductor L1, the first drain DC power supply arm 60 includes a second inductor L2, the second gate DC power supply arm 70 includes a third inductor L3, and the second drain DC power supply arm 80 includes a fourth inductor L4. The inductors have the function of blocking AC while allowing DC to pass, thus isolating the RF signal. This configuration results in a simple circuit structure that is easy to implement.
[0072] It should be noted that in other embodiments, other circuit modules can be set to integrate the radio frequency signal and the DC power supply.
[0073] Based on the above embodiments, the coupler 10 may optionally be a microstrip / stripline slot coupler, a coaxial cavity, a waveguide aperture array, or an MMIC Lange coupler, etc.
[0074] Based on the above embodiments, optionally, the first active device PA1 includes a GaN HEMT device; and the second active device PA2 includes a GaN HEMT device. GaN HEMT devices offer higher power density and operating efficiency, and their use is beneficial for improving circuit performance.
[0075] It should be noted that the above embodiments use GaN HEMT devices as examples for illustration, and are not intended to limit the invention. The invention can be applied to any type of transistor device. Furthermore, when the invention is applied at higher frequencies, since the circuit gain is already relatively low, using the embodiments of the invention may further reduce the gain of the transistor device, affecting performance. Therefore, more advanced manufacturing processes can be used, such as reducing the gate length to increase the transistor device gain, in conjunction with the active negative feedback circuit provided in the embodiments of the invention.
[0076] The present invention also provides a power amplifier, which includes an active negative feedback circuit as provided in any embodiment of the present invention and has corresponding beneficial effects.
[0077] The power amplifier can be a monolithic microwave integrated circuit power amplifier (MMIC PA).
[0078] Furthermore, to improve the linearity of transistor devices in power amplifier circuits, digital pre-distortion (DPD) technology is typically used to correct the radio frequency (RF) signal, thereby improving metrics such as the error vector magnitude (EVM) and adjacent channel leakage ratio (ACLR) of the RF output signal. However, DPD technology not only increases terminal area and cost but also struggles to cover all power levels. The embodiments of this invention do not rely entirely on DPD technology to improve the linearity of the power amplifier, thus saving terminal area, reducing costs, and achieving full coverage across different power levels.
[0079] It should be understood that the various forms of processes shown above can be used, with steps reordered, added, or deleted. For example, the steps described in this invention can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution of this invention can be achieved, and this is not limited herein.
[0080] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.
Claims
1. An active negative feedback circuit, characterized in that, include: A coupler is provided, wherein an RF input signal is received at its input terminal, and the RF input signal is divided into a feedback signal and a main signal; wherein the feedback signal is output from a first output terminal of the coupler, and the main signal is output from a second output terminal of the coupler; a first active device is provided, wherein the gate of the first active device is coupled to the first output terminal of the coupler; a second active device is provided, wherein the gate of the second active device is coupled to the second output terminal of the coupler; the drain of the second active device is coupled to the source of the first active device; the gate of the first active device is also connected to a first gate supply voltage, and the drain of the first active device is connected to a first drain supply voltage; the gate of the second active device is also connected to a second gate supply voltage, and the drain of the second active device is also connected to a second drain supply voltage; the drain of the second active device outputs an RF output signal.
2. The active negative feedback circuit according to claim 1, characterized in that, The size of the first active device is smaller than the size of the second active device.
3. The active negative feedback circuit according to claim 2, characterized in that, The ratio of the gate-drain capacitance to the gate-source capacitance of the first active device is a first set value; and the ratio of the gate-drain capacitance to the gate-source capacitance of the second active device is a first set value; the ratio of the gate width of the first active device to the gate width of the second active device is less than the first set value.
4. The active negative feedback circuit according to claim 2, characterized in that, The ratio of the size of the first active device to the size of the second active device is a second set value; the coupler is configured such that the ratio of the feedback signal output from its first output terminal to the main signal output from its second output terminal is the second set value.
5. The active negative feedback circuit according to claim 1, characterized in that, Also includes: A phase conversion module is connected between the source of the first active device and the drain of the second active device to compensate for the phase difference between the first active device and the second active device.
6. The active negative feedback circuit according to claim 5, characterized in that, The phase transformation module includes a 50-ohm λ / 4 transmission line.
7. The active negative feedback circuit according to claim 1, characterized in that, The first drain supply voltage is twice the second drain supply voltage; the first gate supply voltage is the sum of the gate-source voltage of the first active device and the second drain supply voltage.
8. The active negative feedback circuit according to claim 1, characterized in that, Also includes: A radio frequency input module, wherein the coupler is coupled to the radio frequency input signal through the radio frequency input module; The radio frequency output module outputs the radio frequency output signal through the drain of the second active device.
9. The active negative feedback circuit according to claim 1, characterized in that, Also includes: The first gate DC power supply arm, the gate of the first active device is coupled to the first gate power supply voltage through the first gate DC power supply arm; First drain DC power supply arm, the drain of the first active device is coupled to the first drain power supply voltage through the first drain DC power supply arm; second gate DC power supply arm, the gate of the second active device is coupled to the second gate power supply voltage through the second gate DC power supply arm; second drain DC power supply arm, the drain of the second active device is coupled to the second drain power supply voltage through the second drain DC power supply arm.
10. The active negative feedback circuit according to claim 1, characterized in that, The first active device includes a GaNHEMT device; and the second active device includes a GaN HEMT device.
11. A power amplifier, characterized in that, include: The active negative feedback circuit as described in any one of claims 1-10.