A radio frequency amplifier and radio frequency amplification module

Abstract

The application belongs to the technical field of radio frequency circuit, and specifically provides a radio frequency amplifier and a radio frequency amplification module to solve the problem that the radio frequency amplifier in the prior art is difficult to consider low delay and high pre-distortion compensation simultaneously. The radio frequency amplifier in the application comprises a second harmonic compensation circuit, an isolation circuit and a radio frequency amplification circuit. The radio frequency amplification circuit comprises a common source amplification unit constructed by a field effect tube, and the second harmonic compensation circuit comprises a common source amplification unit constructed by a field effect tube and provided with a second harmonic gain adjusting end. The second harmonic compensation circuit is provided with the second harmonic gain adjusting end, the amplification multiple of the second harmonic is controlled by the adjusting voltage of the adjusting end, thereby offsetting the second harmonic generated by the radio frequency amplification circuit, and further improving the output linearity of the radio frequency amplifier, improving the communication quality and reducing the error rate. Meanwhile, the application synchronously provides a radio frequency amplification module to realize feedback closed loop and complete second harmonic suppression.

Description

Technical Field

[0001] This invention belongs to the field of radio frequency circuit technology, and specifically provides a radio frequency amplifier and a radio frequency amplification module. Background Technology

[0002] As a crucial component of wireless transmitters, radio frequency (RF) amplifiers (RF amplifiers) can suffer from harmonic distortion due to their nonlinear characteristics. The fundamental frequency generates second and third harmonics, creating spurious radiation that interferes with adjacent channel systems. This leads to constellation point distortion and a surge in bit error rate (BER) in complex modulation methods such as OFDM, severely degrading communication quality. Furthermore, the nonlinear characteristics of RF amplifiers can cause intermodulation distortion, generating intermodulation products during multi-carrier input, directly causing adjacent channel interference and reduced system sensitivity. Additionally, it can lead to gain compression, causing output power to no longer increase linearly with input, resulting in a decrease in effective power and gain. To suppress the nonlinearity of RF amplifiers, existing technologies mainly include power back-off, predistortion linearization, or the use of high-linearity devices to build push-pull circuits and balanced power amplifier structures. Predistortion linearization is divided into analog predistortion and digital predistortion. Analog predistortion has slightly lower accuracy and limited bandwidth, while digital predistortion suffers from high system complexity and delay. To address these issues, this invention proposes an RF amplifier and RF amplification module. Summary of the Invention

[0003] The purpose of this invention is to provide a radio frequency amplifier that solves the problem that existing radio frequency amplifiers cannot simultaneously achieve low latency and high predistortion compensation.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0005] A radio frequency amplifier includes: a second harmonic compensation circuit, an isolation circuit, and a radio frequency amplification circuit;

[0006] The radio frequency amplifier circuit includes a common-source amplifier unit constructed using field-effect transistors, and the second harmonic compensation circuit includes a common-source amplifier unit constructed using field-effect transistors and equipped with a second harmonic gain adjustment terminal.

[0007] The input terminal of the second harmonic compensation amplifier circuit serves as the input terminal of the radio frequency amplifier. The output terminal of the second harmonic compensation amplifier circuit is connected to the input terminal of the isolation circuit. The output terminal of the isolation circuit is connected to the input terminal of the radio frequency amplifier circuit. The output terminal of the radio frequency amplifier circuit serves as the output terminal of the radio frequency amplifier.

[0008] The second harmonic gain adjustment terminal of the second harmonic compensation circuit is connected to the adjustment voltage. The second harmonic gain of the second harmonic compensation circuit changes with the adjustment voltage. The second harmonic gain is the amplification factor of the second harmonic compensation circuit for the input radio frequency signal at twice the frequency.

[0009] The input radio frequency signal is input through the input terminal of the second harmonic compensation circuit. By adjusting the voltage, the second harmonic gain of the second harmonic compensation circuit meets the preset requirements, so that the input radio frequency signal is linearly amplified by the radio frequency amplifier circuit.

[0010] Furthermore, the second harmonic compensation circuit includes: a field-effect transistor Q1, an inductor L1, a resistor R1, a resistor R2, a resistor R3, a resistor R4, a capacitor C1, a capacitor C2, and a capacitor C3.

[0011] The first terminal of capacitor C1 serves as the input terminal of the second harmonic compensation circuit. The second terminal of capacitor C1 is connected to the first terminal of resistor R1, and the second terminal of resistor R1 is connected to the second terminal of inductor L1 and the first terminal of resistor R2.

[0012] The first terminal of inductor L1 serves as the second harmonic gain adjustment terminal of the second harmonic compensation circuit, and is connected to the adjustment voltage Vc.

[0013] The second end of resistor R2 is connected to the gate of field-effect transistor Q1 and the first end of capacitor C2, and the second end of capacitor C2 is grounded;

[0014] The first end of resistor R3 is connected to the source of field-effect transistor Q1, and the second end of resistor R3 is grounded.

[0015] The first end of resistor R4 is connected to the supply voltage Vdd, and the second end of resistor R4 is connected to the drain of field-effect transistor Q1 and the first end of capacitor C3. The second end of capacitor C3 serves as the output terminal of the second harmonic compensation circuit.

[0016] Furthermore, the isolation circuit includes: a field-effect transistor Q2, an inductor L2, a resistor R5, and a capacitor C4;

[0017] The gate of the field-effect transistor Q2 serves as the input terminal of the isolation circuit and is connected to the output terminal of the second harmonic compensation circuit.

[0018] The first terminal of inductor L2 is connected to the supply voltage Vdd, and the second terminal of inductor L2 is connected to the drain of field-effect transistor Q2;

[0019] The source of the field-effect transistor Q2 is connected to the first terminal of resistor R5 and the first terminal of capacitor C4. The second terminal of resistor R5 is grounded, and the second terminal of capacitor C4 serves as the output terminal of the isolation circuit.

[0020] Furthermore, the radio frequency amplifier circuit includes: field-effect transistor Q3 and field-effect transistor Q4;

[0021] The gate of MOSFET Q3 serves as the input terminal of the RF amplifier circuit and is connected to the output terminal of the isolation circuit. The source of MOSFET Q3 is grounded, and the drain of MOSFET Q3 is connected to the source of MOSFET Q4. The gate of MOSFET Q4 is connected to the bias voltage Vb, and the drain of MOSFET Q4 is connected to the supply voltage Vdd. At the same time, the drain of MOSFET Q4 is led out to the output terminal of the RF amplifier circuit.

[0022] Furthermore, the radio frequency amplifier circuit also includes inductors L3 and L4, with inductor L3 connected between the gate of the field-effect transistor Q4 and the bias voltage source, and inductor L4 connected between the drain of the field-effect transistor Q4 and the power supply voltage source.

[0023] Furthermore, the radio frequency amplifier circuit also includes: a resistor R6 and a capacitor C5. The first end of the resistor R6 is connected to the drain of the field-effect transistor Q4, and the second end of the resistor R6 is connected to the first end of the capacitor C5. The second end of the capacitor C5 serves as the output terminal of the radio frequency amplifier circuit.

[0024] Furthermore, the preset requirement for the second harmonic gain of the second harmonic compensation circuit is as follows: ,in, This represents the second-order gain coefficient of the second-harmonic compensation circuit. This represents the linear gain coefficient of the RF amplifier circuit. This represents the second-order gain coefficient of the RF amplifier circuit.

[0025] Meanwhile, based on the above-mentioned radio frequency amplifier, the present invention also provides a radio frequency amplification module, including: the above-mentioned radio frequency amplifier, and further including: a coupler, a bandpass filter, a detector and a control unit;

[0026] The lower cutoff frequency of the bandpass filter is higher than the frequency of the input radio frequency signal of the radio frequency amplifier, and the upper cutoff frequency of the bandpass filter is higher than twice the frequency of the input radio frequency signal of the radio frequency amplifier.

[0027] The input terminal of the coupler is connected to the output terminal of the radio frequency amplifier circuit, the output terminal of the coupler is connected to the input terminal of the bandpass filter, the output terminal of the bandpass filter is connected to the input terminal of the detector, and the output terminal of the detector is connected to the signal input terminal of the control unit.

[0028] The output terminal of the control unit outputs the adjustment voltage of the second harmonic compensation circuit in the radio frequency amplifier according to the output signal of the detector, thus forming a feedback closed loop.

[0029] Furthermore, the detector includes: a phase-locked loop, a phase shifter, an analog multiplier, and a low-pass filter;

[0030] The reference terminal of the phase-locked loop is connected to the input radio frequency signal of the radio frequency amplifier, the input terminal of the phase shifter is connected to the output terminal of the phase-locked loop, the two input terminals of the analog multiplier are respectively connected to the output terminal of the phase shifter and the output terminal of the bandpass filter, the output terminal of the analog multiplier is connected to the input terminal of the low-pass filter, and the output terminal of the low-pass filter serves as the output terminal of the detector.

[0031] When a reference radio frequency signal is input to the reference terminal of the phase-locked loop, the output terminal of the phase-locked loop outputs a frequency-doubled signal of the reference radio frequency signal.

[0032] Furthermore, the regulating voltage is expressed as:

[0033] ,

[0034] in, The regulating voltage for the second harmonic compensation circuit. This is the proportionality coefficient. The integral coefficient is... This is the output signal of the detector.

[0035] Based on the above technical solution, the beneficial effects of the present invention are as follows:

[0036] This invention provides a radio frequency (RF) amplifier, comprising: a second harmonic compensation circuit, an isolation circuit, and an RF amplification circuit; wherein, the RF amplification circuit includes a common-source amplification unit constructed using field-effect transistors (FETs), and the second harmonic compensation circuit includes a common-source amplification unit constructed using FETs and equipped with a second harmonic gain adjustment terminal; the second harmonic compensation circuit is provided with a second harmonic gain adjustment terminal, and the amplification factor of the second harmonic is controlled by adjusting the voltage of the adjustment terminal, thereby canceling the second harmonic generated by the RF amplification circuit, thereby improving the output linearity of the RF amplifier, improving communication quality, and reducing the bit error rate.

[0037] Simultaneously, this invention also provides an RF amplification module, including a coupler, a bandpass filter, a detector, and a control unit. The detector obtains the second harmonic amplitude contained in the output RF signal, and the control unit outputs the input voltage of the adjustment terminal of the second harmonic compensation circuit according to the output signal of the detector, realizing a feedback closed loop, thereby completing the compensation of the harmonic signal. Therefore, this invention can significantly improve the linearity of RF amplification and suppress the generation of second harmonics through the RF amplification module. Compared with digital predistortion RF amplification modules, it has less delay and significantly reduced complexity; compared with analog predistortion RF amplification modules, it has higher output linearity. Attached Figure Description

[0038] Figure 1 The schematic diagram of the second harmonic compensation circuit in the radio frequency amplifier provided by the present invention.

[0039] Figure 2 The schematic diagram of the isolation circuit and the radio frequency amplification circuit in the radio frequency amplifier provided by the present invention.

[0040] Figure 3 The schematic diagram of the radio frequency amplification module provided by the present invention. Detailed Implementation

[0041] To make the objectives, technical solutions, and beneficial effects of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0042] This invention provides a radio frequency amplifier, comprising: a second harmonic compensation circuit, an isolation circuit, and a radio frequency amplification circuit;

[0043] The radio frequency amplifier circuit includes a common-source amplifier unit constructed using field-effect transistors, and the second harmonic compensation circuit includes a common-source amplifier unit constructed using field-effect transistors and equipped with a second harmonic gain adjustment terminal.

[0044] The input terminal of the second harmonic compensation amplifier circuit serves as the input terminal (Vin) of the radio frequency amplifier. The output terminal of the second harmonic compensation amplifier circuit is connected to the input terminal of the isolation circuit. The output terminal of the isolation circuit is connected to the input terminal of the radio frequency amplifier circuit. The output terminal of the radio frequency amplifier circuit serves as the output terminal (Vout) of the radio frequency amplifier.

[0045] The second harmonic gain adjustment terminal of the second harmonic compensation circuit is connected to an adjustment voltage (Vc). The second harmonic gain of the second harmonic compensation circuit changes with the adjustment voltage. The second harmonic gain is the amplification factor of the second harmonic compensation circuit for the input radio frequency signal at twice the frequency.

[0046] The input radio frequency signal is input through the input terminal of the second harmonic compensation circuit. By adjusting the voltage, the second harmonic gain of the second harmonic compensation circuit meets the preset requirements, so that the input radio frequency signal is linearly amplified by the radio frequency amplifier circuit.

[0047] Specifically, the radio frequency amplifier circuit in this invention includes an amplifier unit built on a common-source structure based on a field-effect transistor. Due to the characteristics of the field-effect transistor, this unit will generate the second harmonic of the input signal. For an enhancement-mode MOSFET, the relationship between its drain current in the saturation region and its gate voltage satisfies the square law (ideal model).

[0048] ,

[0049] in, Drain current, Gate-source voltage, Threshold voltage, This is a process constant;

[0050] The square law dictates that the relationship between drain current and gate-source voltage is a quadratic curve, not a linear one. Only within a very small signal range near the quiescent operating point can the curve be approximated as a straight line (small-signal linear approximation) through Taylor expansion, achieving approximate linear amplification. Once the input signal amplitude increases, the change in gate-source voltage will cover the nonlinear region of the curve, and the change in drain current will no longer be proportional to the gate-source voltage, directly causing nonlinear distortion.

[0051] For the common-source amplification unit used in this embodiment, its nonlinear transmission equation can be expanded into a polynomial using Taylor series. Since the higher-order terms account for a small proportion, the higher-order small terms are ignored, and only the second-order nonlinearity is retained. Its transmission equation is expressed as follows:

[0052] ,

[0053] in, The output of the common-source amplifier unit. The linear gain coefficient of the common-source amplifier unit. For the input of the common-source amplifier unit, This represents the second-order gain coefficient of the common-source amplifier unit;

[0054] If the input of the common-source amplifier unit contains a sine wave ( , Angular frequency, (where time is the variable), then the quadratic term in the transport equation expands to:

[0055] ,

[0056] Therefore, it can be seen that after the sine wave is nonlinearly amplified (after double gain amplification), the output waveform will generate a second harmonic waveform.

[0057] Based on this, the present invention provides a second harmonic compensation circuit and an isolation circuit at the front end of the radio frequency amplifier circuit; wherein, the second harmonic compensation circuit generates a second harmonic signal that compensates for the above-mentioned nonlinear amplification characteristics, adjusts its amplification factor, and cancels the nonlinearity; and, the circuit is provided with a second harmonic gain adjustment terminal, and by changing the adjustment voltage of the adjustment terminal, its second harmonic amplification factor is changed accordingly.

[0058] In terms of specific connection structure, the second harmonic compensation circuit of the present invention has an input terminal, an output terminal and a second harmonic gain adjustment terminal, which are respectively used to input radio frequency signal (amplified signal), output signal (signal containing second harmonic amplification) and adjust voltage.

[0059] The output of the second harmonic compensation circuit is connected to the input of the isolation circuit. The isolation circuit is used to isolate the second harmonic compensation circuit from the RF amplifier circuit and to perform impedance matching. The RF signal is output to the RF amplifier circuit through the isolation circuit. Finally, after being amplified by the RF amplifier circuit, a high linearity RF amplified signal is output.

[0060] In some embodiments, the second harmonic compensation circuit is as follows: Figure 1 As shown, it specifically includes: field-effect transistor Q1, inductor L1, resistor R1, resistor R2, resistor R3, resistor R4, capacitor C1, capacitor C2, and capacitor C3.

[0061] The first terminal of capacitor C1 serves as the input terminal of the second harmonic compensation circuit. The second terminal of capacitor C1 is connected to the first terminal of resistor R1, and the second terminal of resistor R1 is connected to the second terminal of inductor L1 and the first terminal of resistor R2.

[0062] The first terminal of inductor L1 serves as the second harmonic gain adjustment terminal of the second harmonic compensation circuit, and is connected to the adjustment voltage Vc.

[0063] The second end of resistor R2 is connected to the gate of field-effect transistor Q1 and the first end of capacitor C2, and the second end of capacitor C2 is grounded;

[0064] The first end of resistor R3 is connected to the source of field-effect transistor Q1, and the second end of resistor R3 is grounded.

[0065] The first end of resistor R4 is connected to the supply voltage Vdd, and the second end of resistor R4 is connected to the drain of field-effect transistor Q1 and the first end of capacitor C3. The second end of capacitor C3 serves as the output terminal of the second harmonic compensation circuit.

[0066] Specifically, the common-source amplifier unit of the radio frequency amplifier circuit in this invention typically operates in the saturation region, meaning that the voltage relationship between each electrode satisfies: and Similarly, the second harmonic compensation circuit also adopts a common-source structure with saturated amplification, and its transmission equation is expressed as:

[0067] ,

[0068] in, For the RF output of the second harmonic compensation circuit, This is the RF input for the second harmonic compensation circuit. This represents the linear gain coefficient of the second harmonic compensation circuit. This represents the second-order gain coefficient of the second harmonic compensation circuit.

[0069] Typically, the amplification factor of an isolation circuit is 1. Therefore, by combining the transmission equations of the second harmonic compensation circuit and the RF amplifier circuit, we obtain:

[0070] ,

[0071] Ignoring higher-order terms, we get: ,

[0072] To eliminate the second harmonic, then: Therefore, the condition for obtaining second harmonic compensation is: The linear gain coefficient of a typical second harmonic compensation circuit If set to 1, the compensation conditions will be updated as follows: In other words, adjusting the second-order gain coefficient of the second harmonic compensation circuit. This is also the second harmonic gain of the aforementioned second harmonic compensation circuit, thereby completing the compensation of the second harmonic.

[0073] Combination Figure 1 The core of the second harmonic compensation circuit of this invention is a field-effect transistor Q1, which operates in the shallow saturation region. Its gate is connected to an adjustable voltage Vc through an inductor L1, and a source resistor R3 is connected to the source. By changing the adjustable voltage Vc, the static operating point of the gate of the field-effect transistor Q1 can be changed, and the second-order gain coefficient of the second harmonic compensation circuit can be further adjusted. This is because changing the gate voltage can change the channel length, and the corresponding modulation effect leads to a change in the secondary gain coefficient.

[0074] Specifically, considering the channel modulation effect of the field-effect transistor, the drain current is expressed as:

[0075] ,

[0076] in, The channel length modulation coefficient, This is the voltage between the drain and the source.

[0077] The voltage between the drain and source:

[0078] ,

[0079] in, This refers to the drain current under static conditions. Let R3 be the resistance value (source resistor). The value of resistor R4 (drain resistor);

[0080] The drain current under static conditions (ideal conditions, neglecting channel modulation effect) is expressed as:

[0081] ,

[0082] in, This represents the voltage between the gate and source under static conditions.

[0083] In summary, when the gate voltage is changed by adjusting the voltage Vc, the drain current under static conditions... As a result, the voltage between the drain and source changes. When the synchronization changes, the channel length modulation effect changes, and the corresponding quadratic gain coefficient changes. This allows for adjustment; thus, the present invention can change the secondary gain coefficient by adjusting the voltage Vc. When the compensation condition is met, the second harmonic is canceled out.

[0084] To go even further, such as Figure 1 In the second harmonic compensation circuit shown, the inductor L1 serves to pass DC and block AC. For radio frequency (RF) signals, its impedance is relatively large, blocking both the input and output RF signals, thus avoiding RF signal loss and ensuring signal transmission efficiency and gain accuracy. The resistor R2 and capacitor C2 form a low-pass filter, which can filter out spurious waveforms in the input RF signal. The capacitor C1 is the input coupling capacitor, the resistor R1 is the input impedance matching resistor, and the capacitor C3 is the output coupling capacitor.

[0085] In some implementations, the isolation circuit is as follows: Figure 2 As shown, it includes: field-effect transistor Q2, inductor L2, resistor R5 and capacitor C4;

[0086] The gate of the field-effect transistor Q2 serves as the input terminal of the isolation circuit and is connected to the output terminal of the second harmonic compensation circuit.

[0087] The first terminal of inductor L2 is connected to the supply voltage Vdd, and the second terminal of inductor L2 is connected to the drain of field-effect transistor Q2;

[0088] The source of the field-effect transistor Q2 is connected to the first terminal of resistor R5 and the first terminal of capacitor C4. The second terminal of resistor R5 is grounded, and the second terminal of capacitor C4 serves as the output terminal of the isolation circuit.

[0089] In some embodiments, the radio frequency amplifier circuit is as follows: Figure 2 As shown, it includes: field-effect transistor Q3 and field-effect transistor Q4;

[0090] The gate of MOSFET Q3 serves as the input terminal of the RF amplifier circuit and is connected to the output terminal of the isolation circuit. The source of MOSFET Q3 is grounded, and the drain of MOSFET Q3 is connected to the source of MOSFET Q4. The gate of MOSFET Q4 is connected to the bias voltage Vb, and the drain of MOSFET Q4 is connected to the supply voltage Vdd. At the same time, the drain of MOSFET Q4 is led out to the output terminal of the RF amplifier circuit.

[0091] In some embodiments, the radio frequency amplifier circuit further includes inductors L3 and L4, wherein inductor L3 is connected between the gate of the field-effect transistor Q4 and the bias voltage source, and inductor L4 is connected between the drain of the field-effect transistor Q4 and the power supply voltage source.

[0092] In some embodiments, the radio frequency amplifier circuit further includes: a resistor R6 and a capacitor C5, the first end of the resistor R6 is connected to the drain of the field-effect transistor Q4, the second end of the resistor R6 is connected to the first end of the capacitor C5, and the second end of the capacitor C5 serves as the output terminal of the radio frequency amplifier circuit.

[0093] Specifically, such as Figure 2 As shown, in the isolation circuit, the source of the field-effect transistor Q2 is connected to a source resistor R5, and is connected to a coupling capacitor C4 through the source terminal. This part is a source follower. The resistance value of R5 can be set so that the RF signal output by the coupling capacitor C4 follows the input signal of the gate of the field-effect transistor Q2, and the gain is controlled to 1. This circuit is mainly used to achieve impedance matching and signal isolation, so as to avoid the input impedance change of the subsequent circuit from affecting the operating point of the preceding circuit.

[0094] The RF amplifier circuit is a common-source, common-gate structure. The RF signal is input from the gate of MOSFET Q3 and output from the drain. The signal output from MOSFET Q3 is then input to the source of MOSFET Q4. The bias voltage Vb adjusts the gate voltage of MOSFET Q4, keeping the gate voltage of MOSFET Q4 fixed and operating in the deep saturation region, thus suppressing its operating point channel modulation effect. When the RF signal is input from the gate of MOSFET Q3 and output from the drain of MOSFET Q4, the RF signal is almost not reflected and almost not transmitted to the two power supply sides due to the high impedance of inductors L3 and L4. Since the MOSFET is ideally a voltage-controlled current source, the RF signal propagates in the form of current. The RF amplifier circuit is equivalent to a high-output-impedance current source, giving it extremely strong load driving capability. In addition, resistor R6 is an output impedance matching resistor used to match the impedance of the output load, and capacitor C5 is an RF output coupling capacitor.

[0095] Based on the above-mentioned radio frequency amplifier, the present invention further provides a radio frequency amplification module, such as... Figure 3 As shown, it includes: the radio frequency amplifier, and further includes: a coupler, a bandpass filter, a detector, and a control unit;

[0096] The lower cutoff frequency of the bandpass filter is higher than the frequency of the input radio frequency signal of the radio frequency amplifier, and the upper cutoff frequency of the bandpass filter is higher than twice the frequency of the input radio frequency signal of the radio frequency amplifier.

[0097] The input terminal of the coupler is connected to the output terminal of the radio frequency amplifier circuit, the output terminal of the coupler is connected to the input terminal of the bandpass filter, the output terminal of the bandpass filter is connected to the input terminal of the detector, and the output terminal of the detector is connected to the signal input terminal of the control unit.

[0098] The output terminal of the control unit outputs the adjustment voltage Vc of the second harmonic compensation circuit adjustment terminal in the radio frequency amplifier according to the signal output by the detector.

[0099] In some embodiments, the detector includes: a phase-locked loop, a phase shifter, an analog multiplier, and a low-pass filter;

[0100] The reference terminal of the phase-locked loop is connected to the input radio frequency signal of the radio frequency amplifier, the input terminal of the phase shifter is connected to the output terminal of the phase-locked loop, the two input terminals of the analog multiplier are respectively connected to the output terminal of the phase shifter and the output terminal of the bandpass filter, the output terminal of the analog multiplier is connected to the input terminal of the low-pass filter, and the output terminal of the low-pass filter serves as the output terminal of the detector.

[0101] When a reference radio frequency signal is input to the reference terminal of the phase-locked loop, the output terminal of the phase-locked loop outputs a frequency-doubled signal of the reference radio frequency signal.

[0102] Specifically, in the radio frequency amplification module provided by the present invention, an adjustable voltage is generated at the adjustment terminal of the second harmonic compensation circuit according to a first formula and the output signal of the detector, wherein the first formula is:

[0103] ,

[0104] in, This is the adjustment voltage at the adjustment terminal of the second harmonic compensation circuit. This is the proportionality coefficient. The integral coefficient is... This is the output signal of the detector;

[0105] like Figure 3 As shown, the coupler obtains a signal from the output of the RF amplifier. The bandpass filter filters the obtained signal, retaining the second harmonic component of the input signal. In other words, the second harmonic is extracted by the bandpass filter. The second harmonic is then detected to extract the harmonic amplitude. This amplitude indicates the effect of the second harmonic compensation circuit. The control unit outputs the control voltage Vc according to the harmonic amplitude, thus forming a feedback closed loop, thereby achieving second harmonic suppression and linear amplification.

[0106] Regarding the control logic, the first formula mentioned above is adopted. This formula provides the control logic for controlling the second harmonic compensation circuit based on the output signal of the detector. In fact, this control logic is proportional-integral logic, which can achieve high linearity in steady state. Simulation tests show that, through the above control logic, the second harmonic suppression ratio reaches more than 60dB, and the harmonic distortion is no higher than 0.001%.

[0107] In fact, the output signal of the detector in the first formula above is an amplitude signal with a positive or negative sign. When the amplitude signal is negative, it indicates that the phase of the second harmonic contained in the output radio frequency signal is opposite to the phase of the second harmonic of the input radio frequency signal.

[0108] The detector's structure includes a second harmonic phase-locked loop (PLL). This PLL takes the RF signal input from the RF amplifier as its input and outputs a second harmonic of the input RF signal. This second harmonic signal is then phase-shifted (the phase difference between the phase-shifted second harmonic signal and the second harmonic is...). , The purpose is to avoid the phase difference between the second harmonic and the second harmonic. or difference The second harmonic output from the bandpass filter is fed into the analog multiplier, and the calculation logic of the analog multiplier conforms to the following formula:

[0109] ,

[0110] in, This is a double frequency of the RF signal output by the phase-locked loop. To extract the second harmonic from the bandpass filter, The amplitude of the second harmonic. This represents the phase difference between the second harmonic and the second harmonic of the radio frequency signal. For time variables, Angular frequency;

[0111] The above formula shows that after passing through the analog multiplier, the output signal includes a DC component. ) and a fourth harmonic signal ( The analog multiplier, after being filtered by a low-pass filter, yields a DC component, which represents the signed harmonic amplitude.

[0112] In summary, this invention provides a radio frequency amplifier, including a second harmonic compensation circuit, an isolation circuit, and a radio frequency amplification circuit. The radio frequency amplification circuit includes a common-source amplification unit constructed using field-effect transistors (FETs), and the second harmonic compensation circuit includes a common-source amplification unit constructed using FETs and equipped with a second harmonic gain adjustment terminal. The compensation circuit is equipped with a second harmonic multiplier compensation terminal, which can adjust the multiplier of the second harmonic by adjusting the compensation terminal, thereby canceling the second harmonic generated by the radio frequency amplification circuit, thereby improving the linearity of the radio frequency amplifier output, and thus improving communication quality and reducing the bit error rate.

[0113] This invention also provides an RF amplification module, including a coupler, a bandpass filter, a detector, and a control unit. The detector can obtain the second harmonic amplitude contained in the output RF signal. The output terminal of the control unit outputs an adjustment voltage to adjust the adjustment terminal of the second harmonic compensation circuit according to the output signal of the detector, so as to complete the compensation of the harmonic signal. This RF amplification module can significantly improve the linearity of RF amplification and suppress the generation of second harmonics. Compared with digital predistortion RF amplification modules, it has less delay and significantly reduced complexity. Compared with analog predistortion RF amplification modules, it has higher output linearity.

[0114] The above description is merely a specific embodiment of the present invention. Any feature disclosed in this specification may be replaced by other equivalent or similar features unless otherwise specified. All disclosed features, or steps in all methods or processes, may be combined in any way except for mutually exclusive features and / or steps.

Claims

1. A radio frequency amplifier, characterized in that, include: Second harmonic compensation circuit, isolation circuit, radio frequency amplifier circuit; The radio frequency amplifier circuit includes a common-source amplifier unit constructed using field-effect transistors, and the second harmonic compensation circuit includes a common-source amplifier unit constructed using field-effect transistors and equipped with a second harmonic gain adjustment terminal. The input terminal of the second harmonic compensation circuit serves as the input terminal of the radio frequency amplifier. The output terminal of the second harmonic compensation circuit is connected to the input terminal of the isolation circuit. The output terminal of the isolation circuit is connected to the input terminal of the radio frequency amplifier circuit. The output terminal of the radio frequency amplifier circuit serves as the output terminal of the radio frequency amplifier. The second harmonic gain adjustment terminal of the second harmonic compensation circuit is connected to the adjustment voltage. The second harmonic gain of the second harmonic compensation circuit changes with the adjustment voltage. The second harmonic gain is the amplification factor of the second harmonic compensation circuit for the input radio frequency signal at twice the frequency. The input radio frequency signal is input through the input terminal of the second harmonic compensation circuit. By adjusting the voltage, the second harmonic gain of the second harmonic compensation circuit meets the preset requirements, so that the input radio frequency signal is linearly amplified by the radio frequency amplifier circuit. The preset requirement for the second harmonic gain of the second harmonic compensation circuit is as follows: ,in, This represents the second-order gain coefficient of the second-harmonic compensation circuit. This represents the linear gain coefficient of the RF amplifier circuit. This represents the second-order gain coefficient of the RF amplifier circuit.

2. The radio frequency amplifier according to claim 1, characterized in that, The second harmonic compensation circuit includes: a field-effect transistor Q1, an inductor L1, a resistor R1, a resistor R2, a resistor R3, a resistor R4, a capacitor C1, a capacitor C2, and a capacitor C3. The first terminal of capacitor C1 serves as the input terminal of the second harmonic compensation circuit. The second terminal of capacitor C1 is connected to the first terminal of resistor R1, and the second terminal of resistor R1 is connected to the second terminal of inductor L1 and the first terminal of resistor R2. The first terminal of inductor L1 serves as the second harmonic gain adjustment terminal of the second harmonic compensation circuit, and is connected to the adjustment voltage Vc. The second end of resistor R2 is connected to the gate of field-effect transistor Q1 and the first end of capacitor C2, and the second end of capacitor C2 is grounded; The first end of resistor R3 is connected to the source of field-effect transistor Q1, and the second end of resistor R3 is grounded. The first end of resistor R4 is connected to the supply voltage Vdd, and the second end of resistor R4 is connected to the drain of field-effect transistor Q1 and the first end of capacitor C3. The second end of capacitor C3 serves as the output terminal of the second harmonic compensation circuit.

3. The radio frequency amplifier according to claim 1, characterized in that, The isolation circuit includes: a field-effect transistor Q2, an inductor L2, a resistor R5, and a capacitor C4; The gate of the field-effect transistor Q2 serves as the input terminal of the isolation circuit and is connected to the output terminal of the second harmonic compensation circuit. The first terminal of inductor L2 is connected to the supply voltage Vdd, and the second terminal of inductor L2 is connected to the drain of field-effect transistor Q2; The source of the field-effect transistor Q2 is connected to the first terminal of resistor R5 and the first terminal of capacitor C4. The second terminal of resistor R5 is grounded, and the second terminal of capacitor C4 serves as the output terminal of the isolation circuit.

4. The radio frequency amplifier according to claim 1, characterized in that, The radio frequency amplifier circuit includes: field-effect transistor Q3 and field-effect transistor Q4; The gate of MOSFET Q3 serves as the input terminal of the RF amplifier circuit and is connected to the output terminal of the isolation circuit. The source of MOSFET Q3 is grounded, and the drain of MOSFET Q3 is connected to the source of MOSFET Q4. The gate of MOSFET Q4 is connected to the bias voltage Vb, and the drain of MOSFET Q4 is connected to the supply voltage Vdd. At the same time, the drain of MOSFET Q4 is led out to the output terminal of the RF amplifier circuit.

5. The radio frequency amplifier according to claim 4, characterized in that, The radio frequency amplifier circuit further includes inductors L3 and L4. Inductor L3 is connected between the gate of the field-effect transistor Q4 and the bias voltage source, and inductor L4 is connected between the drain of the field-effect transistor Q4 and the power supply voltage source.

6. The radio frequency amplifier according to claim 4, characterized in that, The radio frequency amplifier circuit also includes a resistor R6 and a capacitor C5. The first end of the resistor R6 is connected to the drain of the field-effect transistor Q4, and the second end of the resistor R6 is connected to the first end of the capacitor C5. The second end of the capacitor C5 serves as the output terminal of the radio frequency amplifier circuit.

7. A radio frequency amplification module, characterized in that, include: The radio frequency amplifier of claim 1 further includes: a coupler, a bandpass filter, a detector, and a control unit; The lower cutoff frequency of the bandpass filter is higher than the frequency of the input radio frequency signal of the radio frequency amplifier, and the upper cutoff frequency of the bandpass filter is higher than twice the frequency of the input radio frequency signal of the radio frequency amplifier. The input terminal of the coupler is connected to the output terminal of the radio frequency amplifier circuit, the output terminal of the coupler is connected to the input terminal of the bandpass filter, the output terminal of the bandpass filter is connected to the input terminal of the detector, and the output terminal of the detector is connected to the signal input terminal of the control unit. The output terminal of the control unit outputs the adjustment voltage of the second harmonic compensation circuit in the radio frequency amplifier according to the output signal of the detector, thus forming a feedback closed loop.

8. The radio frequency amplification module according to claim 7, characterized in that, The detector includes: a phase-locked loop, a phase shifter, an analog multiplier, and a low-pass filter; The reference terminal of the phase-locked loop is connected to the input radio frequency signal of the radio frequency amplifier, the input terminal of the phase shifter is connected to the output terminal of the phase-locked loop, the two input terminals of the analog multiplier are respectively connected to the output terminal of the phase shifter and the output terminal of the bandpass filter, the output terminal of the analog multiplier is connected to the input terminal of the low-pass filter, and the output terminal of the low-pass filter serves as the output terminal of the detector. When a reference radio frequency signal is input to the reference terminal of the phase-locked loop, the output terminal of the phase-locked loop outputs a frequency-doubled signal of the reference radio frequency signal.

9. The radio frequency amplification module according to claim 7, characterized in that, The regulating voltage is expressed as: ， in, The regulating voltage for the second harmonic compensation circuit. This is the proportionality coefficient. The integral coefficient is... This is the output signal of the detector.

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