A microwave / millimeter-wave Class B / J power amplifier

Abstract

A microwave / millimeter-wave Class B / J power amplifier includes a drive amplification and harmonic generation circuit and an amplifier circuit. The radio frequency (RF) input signal RFin is input through the signal input terminal of the drive amplification and harmonic generation circuit, and the signal output terminal of the drive amplification and harmonic generation circuit is connected to the signal input terminal of the amplifier circuit. The amplifier circuit outputs the amplified RF signal. This invention utilizes a pre-stage drive amplifier of a multi-stage power amplifier to simultaneously amplify the fundamental signal, generate harmonics, and control the phase and amplitude of the harmonics. The fundamental and harmonic signals are simultaneously input into the main amplifier to achieve waveform control and improve power amplifier efficiency. By controlling the phase difference and amplitude ratio between the second harmonic and the fundamental wave through the drive amplifier, the efficiency of the Class B / J power amplifier can be improved, reaching a maximum efficiency of 95.2%. Furthermore, the normalized voltage peak value is lower than that of traditional Class B / J power amplifiers. It features a simple structure, significantly improved efficiency, enhanced circuit reliability, small area, and low cost.

Description

Technical Field

[0001] This invention relates to the field of power amplifier technology, and in particular to a microwave / millimeter-wave Class B / J power amplifier. Background Technology

[0002] Modern wireless communication applications, such as satellite communication and 5G communication, are increasingly demanding high-efficiency, high-speed, low-cost, and highly integrated RF front-ends, creating an urgent need for high-output-power, high-efficiency, and low-cost silicon-based microwave / millimeter-wave power amplifiers. However, achieving high-output-power (watt-level), high-efficiency, and wideband silicon-based microwave / millimeter-wave power amplifiers remains a significant challenge.

[0003] The gate bias of a traditional Class B power amplifier is V g Equal to the threshold voltage V of the tube TH The conduction angle is 180°, and the maximum output power is Among them, I DC This is the DC component of the drain current. Class B power amplifiers only consider the influence of the fundamental frequency and do not consider the influence of harmonics on the operating state. At high frequencies, high-order harmonics generated by parasitic parameters may reduce their efficiency.

[0004] Because traditional Class B power amplifiers do not consider the impact of higher harmonics on the operating state of MOSFETs, it is difficult to achieve high efficiency at high frequencies. To achieve high-efficiency power amplification at high frequencies, a Class J power amplifier was designed. Through passive matching circuitry and higher harmonic impedance control, the drain voltage waveform is controlled, and efficiency is improved. The phase difference between the voltage and current in the Class J power amplifier is 45° / -45°.

[0005] Gate bias V of a Class J power amplifier g Equal to the threshold voltage V of the tube TH The resonant cavity at the drain exhibits low impedance at the second harmonic frequency, enabling control of the drain voltage waveform. This conventional Class J power amplifier only controls the fundamental and higher harmonic matching of the passive load, achieving a peak efficiency of only 78.5%, the same as an ideal Class B power amplifier. However, when the fundamental power of the Class J power amplifier is the same as that of the Class B power amplifier, the peak voltage exceeds 2V. DD In silicon-based low-voltage processes, output power and bandwidth must be sacrificed to ensure reliability.

[0006] Existing harmonic injection power amplifiers split the input signal into two paths via a power divider. One path generates higher harmonics through a harmonic generator, then further generates phase- and amplitude-adjustable higher harmonics through a variable phase shifter and variable attenuator, which are then combined with the other signal and output by an amplifier. This technology employs an additional higher harmonic generation circuit and injects harmonics through power combining with the main power amplifier to achieve waveform control and efficiency improvement. However, the additional second harmonic generation circuit increases circuit area and power consumption, limiting efficiency gains.

[0007] In their paper "Theory and Design of High-Efficiency Broadband Class-B / J Power Amplifiers With Active Second Harmonic Injection" (IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES, VOL.71, NO.10, OCTOBER 2023), Liu et al. proposed a theoretical and design method for a high-efficiency broadband continuous-wave Class-B / J power amplifier (PA), combined with active second harmonic injection technology. By injecting the second harmonic component generated by the auxiliary power amplifier, the optimal phase shift parameter α between the drain voltage and current can be appropriately selected, thereby improving the efficiency and power of traditional Class-B / J power amplifiers. However, because this technique uses an additional active second harmonic injection circuit, it increases the circuit area and power consumption, limiting efficiency improvement. Summary of the Invention

[0008] To overcome the shortcomings of the prior art, the present invention aims to provide a microwave / millimeter-wave Class B / J power amplifier that utilizes a multi-stage power amplifier pre-amplifier to simultaneously amplify the fundamental signal, generate harmonics, and control the phase and amplitude of harmonics. This allows the main amplifier to simultaneously input the fundamental and second harmonics, and simultaneously shape the voltage and current waveforms at the drain of the transistor, thereby achieving higher power and efficiency.

[0009] To achieve the above objectives, the present invention provides the following technical solution:

[0010] A microwave / millimeter-wave Class B / J power amplifier includes a drive amplification and harmonic generation circuit and an amplifier circuit. The radio frequency (RF) input signal RFI is input through the signal input terminal of the drive amplification and harmonic generation circuit. The signal output terminal of the drive amplification and harmonic generation circuit is connected to the signal input terminal of the amplifier circuit. The amplifier circuit outputs an amplified RF signal. The drive amplification and harmonic generation circuit is used for input matching and second harmonic generation. The amplifier circuit further amplifies the output signal generated by the drive amplification and second harmonic generation circuit.

[0011] The drive amplification and harmonic generation circuit includes an input matching and harmonic generation circuit and a drive amplification and harmonic phase / amplitude control circuit; the amplification circuit includes a main amplifier and an output matching circuit; wherein the radio frequency input signal RFin is input through the input terminal of the input matching and harmonic generation circuit, the radio frequency signal output terminal of the input matching and harmonic generation circuit is connected to the radio frequency signal input terminal of the drive amplification and harmonic phase / amplitude control circuit, the signal output terminal of the drive amplification and harmonic phase / amplitude control circuit is connected to the signal input terminal of the main amplifier, the signal output terminal of the main amplifier is connected to the output matching circuit, and the output matching circuit outputs a radio frequency signal RFout.

[0012] The input matching and harmonic generation circuit includes a first transformer T1. The radio frequency signal input terminal RFin is connected to the signal input terminal of the first transformer T1. The first transformer T1 performs input matching and single-ended to differential conversion of the signal, and generates second harmonics by utilizing the asymmetry of the transformer.

[0013] The drive amplification and harmonic phase / amplitude control circuit includes a drive amplifier and a second transformer T2, used to complete the amplification of the fundamental and second harmonics and the phase / amplitude control of the fundamental and second harmonics; wherein, the signal output terminal of the drive amplifier is connected to the signal input terminal of the second transformer T2.

[0014] The drain current of the MOS transistor in the main amplifier is:

[0015]

[0016] Where I1 and I2 are the maximum values ​​of the fundamental and second harmonic currents generated at the drain, respectively.

[0017] The drain voltage of the MOS transistor in the main amplifier is:

[0018] v d =(V DD -V th (1-coswt)(1-αsinwt)=(V DD -V th )×(1-coswt-αsinwt+αsinwtcoswt)

[0019] Among them, V DD V is the DC drain voltage of the MOSFET. th α is the threshold voltage of the MOSFET, and α is a design parameter.

[0020] From the above formula, the fundamental impedance and second harmonic impedance required by the output matching circuit can be calculated as follows:

[0021]

[0022] Based on the above expressions for drain current and voltage, the DC power consumption of the microwave / millimeter-wave Class B / J power amplifier is:

[0023]

[0024] Where I1 is the maximum value of the fundamental current generated at the drain, V DD V is the DC drain voltage of the MOSFET. th This is the threshold voltage of the MOSFET.

[0025] The fundamental power of the microwave / millimeter-wave Class B / J power amplifier is:

[0026]

[0027] Based on the DC power consumption and fundamental frequency power, the drain efficiency of the microwave / millimeter-wave Class B / J power amplifier can be calculated as follows:

[0028]

[0029] I1 and I2 satisfy: That is, the conduction angle is 180°.

[0030] Compared with the prior art, the beneficial effects of the present invention are:

[0031] 1. This invention utilizes a multi-stage power amplifier's pre-amplifier (i.e., the driver amplifier and harmonic generator) to simultaneously amplify the fundamental signal, generate harmonics, and control the phase and amplitude of harmonics. The fundamental and harmonic signals are simultaneously input into the main amplifier to achieve waveform control and improve the efficiency of the power amplifier.

[0032] 2. By adjusting the output matching circuit of the main amplifier, the present invention can adjust the matching circuit and the resonant cavity circuit according to the second harmonic component in the input signal.

[0033] 3. This invention uses the asymmetry of the input matching circuit of the driver amplifier to generate a second harmonic, which, together with the amplified fundamental frequency signal, serves as the input signal of the main power amplifier; or it uses the nonlinearity of the active circuit of the driver amplifier to generate a second harmonic, which, together with the amplified fundamental frequency signal, serves as the input signal of the main power amplifier; or it uses other methods to make the driver amplifier generate a second harmonic, which, together with the amplified fundamental frequency signal, serves as the input signal of the main power amplifier; it has the advantages and innovations of simple circuit architecture, no need for additional hardware overhead, high efficiency, and small area.

[0034] 4. This invention improves the efficiency of Class B / J power amplifiers by controlling the phase difference and amplitude ratio between the second harmonic and the fundamental frequency through a driving amplifier. The maximum efficiency can reach 95.2%.

[0035] 5. By adjusting the phase relationship between the fundamental wave and the second harmonic, this invention can reduce the voltage peak value when the phase difference between the two is 90°, thereby improving the output power and bandwidth of the power amplifier and improving its reliability.

[0036] 6. This invention utilizes the existing circuit structure of a multi-stage cascaded power amplifier, without additional hardware overhead or power consumption.

[0037] In summary, this invention utilizes a pre-amplifier of a multi-stage power amplifier to simultaneously amplify the fundamental signal, generate harmonics, and control the phase and amplitude of harmonics. It simultaneously inputs the fundamental and second harmonics to the main amplifier and simultaneously shapes the voltage and current waveforms at the drain of the transistor. This eliminates the need for an additional active second harmonic injection circuit, thereby achieving higher power and efficiency. Attached Figure Description

[0038] Figure 1 This is a schematic diagram of the structural principle of the present invention.

[0039] Figure 2 This is a structural schematic diagram of an embodiment of the present invention.

[0040] Figure 3 This is a comparison chart of the reliability improvement of the present invention compared to the traditional Class B / J power amplifier; wherein, (a) is the reliability improvement chart of the traditional Class B / J power amplifier; and (b) is the reliability improvement chart of the present invention. Detailed Implementation

[0041] To more clearly illustrate the technical solution and advantages of the present invention, the present invention will be described in detail below with reference to specific implementation steps. It should be noted that the implementation steps described below are only for explaining the present invention and are not intended to limit the present invention.

[0042] See Figure 1 A microwave / millimeter-wave Class B / J power amplifier includes a drive amplifier and harmonic generation circuit and an amplifier circuit. The radio frequency (RF) input signal RFin is input through the signal input terminal of the drive amplifier and harmonic generation circuit. The signal output terminal of the drive amplifier and harmonic generation circuit is connected to the signal input terminal of the amplifier circuit. The amplifier circuit outputs an amplified RF signal. The drive amplifier and harmonic generation circuit are used for input matching and second harmonic generation of the power amplifier. Figure 1 RF output from drv The amplifier circuit is used to further amplify and output the output signal generated by the drive amplification and second harmonic generation circuit, i.e. Figure 1 The radio frequency signal RFout is output from the device.

[0043] See Figure 2 , Figure 2This is one embodiment of the present invention. The microwave / millimeter-wave Class B / J power amplifier described in this embodiment includes a drive amplification and harmonic generation circuit and an amplification circuit. The drive amplification and harmonic generation circuit includes an input matching and harmonic generation circuit and a drive amplification and harmonic phase / amplitude control circuit. The amplification circuit includes a main amplifier and an output matching circuit. The radio frequency (RF) input signal RFin is connected to the input terminal of the input matching and harmonic generation circuit. The RF signal output terminal of the input matching and harmonic generation circuit is connected to the RF signal input terminal of the drive amplification and harmonic phase / amplitude control circuit. The signal output terminal of the drive amplification and harmonic phase / amplitude control circuit is connected to the main amplifier. The output terminal of the main amplifier is connected to the output matching circuit, and the output matching circuit outputs a radio frequency (RFout) signal.

[0044] The input matching and harmonic generation circuit includes a first transformer T1. The radio frequency input signal RFin is connected to the signal input terminal of the first transformer T1. The output terminal of the first transformer T1 is connected to the input terminal of the driver amplifier. The positive and negative terminals of the first transformer T1 are connected to the positive and negative terminals of the driver amplifier, respectively. The first transformer T1 performs input matching and single-ended to differential conversion of the signal, and generates second harmonics by utilizing the asymmetry of the first transformer T1.

[0045] The drive amplifier and harmonic phase / amplitude control circuit is used to complete the fundamental and second harmonic amplification and the fundamental and second harmonic phase / amplitude control. Specifically, it includes a drive amplifier and a second transformer T2. The positive and negative terminals of the output of the drive amplifier are connected to the positive and negative terminals of the input of the second transformer T2, respectively. The positive and negative terminals of the output of the second transformer T2 are connected to the positive and negative terminals of the input of the main amplifier, respectively.

[0046] The amplifier circuit performs waveform shaping and Class J power amplification, specifically including a main amplifier and an output matching circuit. The positive and negative terminals of the main amplifier are connected to the positive and negative terminals of the output matching circuit, respectively. The output matching circuit outputs the radio frequency signal RFout.

[0047] In this embodiment, the input matching uses a transformer. The first transformer T1 is a transformer with the main and secondary coils coupled together. The driving amplifier uses a common source and common gate circuit. The second transformer T2 is a transformer with the main and secondary coils coupled together. The main amplifier uses a common source and common gate circuit. The output matching uses a transformer with the main and secondary coils coupled together and a matching capacitor.

[0048] When a signal is input, the non-ideal characteristics of the passive matching circuit of the driver amplifier are used to generate a differential second harmonic signal. The driver amplifier amplifies the fundamental and second harmonic signals and adjusts the phase relationship between the fundamental and second harmonics to make their phase difference 90°, ultimately achieving high-efficiency power output, reducing voltage peak and improving reliability.

[0049] like Figure 3 As shown, the normalized voltage value of the Class B / J power amplifier of the present invention is less than 1.5 times VDD, which reduces the voltage peak value compared with the conventional Class B / J power amplifier; when the fundamental power of the Class J power amplifier of the present invention is the same as that of the Class B power amplifier, the peak voltage at the drain will not exceed 2V. DD This improves the reliability, maximum output power, and available operating bandwidth of the power amplifier.

[0050] The B / J class power amplifier of the present invention utilizes the original circuit structure of a multi-stage cascaded power amplifier, without additional hardware overhead and power consumption. Compared with traditional harmonic injection amplifiers, it has a smaller circuit area and higher efficiency.

[0051] The Class B / J power amplifier of this invention achieves a theoretical maximum efficiency of 95.2%, which is 16.7% higher than that of conventional Class B / J power amplifiers. The normalized voltage of the Class B / J power amplifier of this invention is less than 1.5 times VDD, reducing the voltage peak compared to conventional Class B / J amplifiers. This improves the reliability, maximum output power, and available operating bandwidth of the power amplifier, without additional hardware overhead or power consumption. Furthermore, it features a smaller circuit area and higher efficiency compared to conventional harmonic injection amplifiers.

Claims

1. A microwave / millimeter-wave Class B / J power amplifier, characterized in that, The system includes a drive amplification and harmonic generation circuit and an amplification circuit. The radio frequency (RF) input signal RFI is input through the signal input terminal of the drive amplification and harmonic generation circuit. The signal output terminal of the drive amplification and harmonic generation circuit is connected to the signal input terminal of the amplification circuit, and the amplification circuit outputs the amplified RF signal. The drive amplification and harmonic generation circuit is used for input matching and second harmonic generation. The amplification circuit further amplifies the output signal generated by the drive amplification and second harmonic generation circuit. The drive amplification and harmonic generation circuit includes an input matching and harmonic generation circuit and a drive amplification and harmonic phase / amplitude control circuit. The amplification circuit includes a main amplifier and an output matching circuit. The RF input signal RFI is generated through input matching and harmonic generation. The circuit's input terminal is connected to the input terminal of the input matching and harmonic generation circuit. The RF signal output terminal of the input matching and harmonic generation circuit is connected to the RF signal input terminal of the drive amplification and harmonic phase / amplitude control circuit. The signal output terminal of the drive amplification and harmonic phase / amplitude control circuit is connected to the signal input terminal of the main amplifier. The signal output terminal of the main amplifier is connected to the output matching circuit, which outputs the RF signal RFout. The input matching and harmonic generation circuit includes a first transformer T1. The RF signal input terminal RFin is connected to the signal input terminal of the first transformer T1. The first transformer T1 performs input matching and single-ended to differential signal conversion, and utilizes the transformer's asymmetry to generate the second harmonic. The fundamental impedance and second harmonic impedance required by the output matching circuit are as follows: Where I1 and I2 are the maximum values ​​of the fundamental and second harmonic currents generated at the drain, respectively, V DD V is the DC drain voltage of the MOSFET. th α is the threshold voltage of the MOSFET, and α is a design parameter.

2. The microwave / millimeter-wave Class B / J power amplifier according to claim 1, characterized in that, The drive amplification and harmonic phase / amplitude control circuit includes a drive amplifier and a second transformer T2, used to complete the amplification of the fundamental and second harmonics and the phase / amplitude control of the fundamental and second harmonics; wherein, the signal output terminal of the drive amplifier is connected to the signal input terminal of the second transformer T2.

3. A microwave / millimeter-wave Class B / J power amplifier according to claim 1, characterized in that, The drain current of the MOS transistor in the main amplifier is: The drain voltage of the MOSFET is: v d =(V DD -V th )(1-coswt)(1-αsinwt)=(V DD -V th )× (1-coswt-αsinwt+αsinwtcoswt).

4. A microwave / millimeter-wave Class B / J power amplifier according to claim 1, characterized in that, The DC power consumption of the microwave / millimeter-wave Class B / J power amplifier is: Where I1 is the maximum value of the fundamental current generated at the drain, V DD V is the DC drain voltage of the MOSFET. th This is the threshold voltage of the MOSFET; The fundamental power of the microwave / millimeter-wave Class B / J power amplifier is: Based on the DC power consumption and fundamental frequency power, the drain efficiency of the microwave / millimeter-wave Class B / J power amplifier can be calculated as follows:

5. A microwave / millimeter-wave Class B / J power amplifier according to claim 4, characterized in that, I1 and I2 satisfy: That is, the conduction angle is 180°, and the phase difference between the fundamental frequency and the second harmonic of the amplifier is 90°.

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