Biasing circuit and radio frequency power amplifier

Abstract

The invention discloses a biasing circuit and a radio frequency power amplifier, and belongs to the technical field of amplifiers. The bias circuit comprises bias control modules which are arranged in one-to-one correspondence with amplifiers at all levels in the radio frequency power amplifier; the bias control module comprises a coupling control unit and a clamping transistor. The coupling control unit is used for filtering the radio-frequency signal of the bias end and then outputting the radio-frequency signal through a second connecting end of the coupling control unit; a parasitic clamping diode is arranged between the control electrode and the first electrode of the clamping transistor, and the parasitic clamping diode is used for chopping a signal of the second connecting end of the coupling control unit, so that the change trend of the direct current component of the voltage of the first electrode of the clamping transistor is the same as the change trend of the envelope amplitude of the radio frequency signal; the voltage of the first electrode of the clamping transistor passes through the coupling control unit and then is provided to the bias end as a bias voltage. According to the embodiment of the invention, the working state of the amplifier is optimized by adjusting the bias voltage in real time.

Description

Technical Field

[0001] The present invention relates to the technical field of amplifiers, and in particular to a bias circuit and a radio frequency power amplifier. Background Art

[0002] As a core component of wireless communication systems, radio frequency (RF) power amplifiers play a vital role in the signal transmission process. Their main task is to amplify the weak input signal to a power level sufficient to drive the antenna, thereby achieving long-distance communication. The performance of RF power amplifiers directly affects the signal quality, transmission range and overall efficiency of wireless communication systems, so their importance is self-evident.

[0003] However, RF power amplifiers face severe challenges of nonlinear distortion in actual operation. This distortion is mainly manifested in amplitude distortion and phase distortion, which is more significant in high-power output states. When the amplifier enters the nonlinear working area, the distortion of the output signal increases sharply, which not only reduces the signal quality, but also may lead to a significant increase in the bit error rate, thus affecting the stability and reliability of the entire communication system. Summary of the invention

[0004] The present invention provides a bias circuit and a radio frequency power amplifier, which adopt a dynamic bias technology to compensate for the intrinsic distortion behavior of the radio frequency power amplifier, optimize the working state of the amplifier by adjusting the bias voltage in real time, and are beneficial to improving the stability and reliability of the communication system.

[0005] In a first aspect, an embodiment of the present invention provides a bias circuit, which is applied to a radio frequency power amplifier; the radio frequency power amplifier includes at least one amplifier stage;

[0006] The bias circuit comprises: a bias control module arranged in one-to-one correspondence with each of the amplifiers;

[0007] The bias control module comprises:

[0008] A coupling control unit; a first connection end of the coupling control unit is connected to the bias end of the amplifier corresponding to the bias control module; the coupling control unit is used to filter the radio frequency signal of the bias end and output it through the second connection end of the coupling control unit;

[0009] A clamping transistor; the control electrode of the clamping transistor is connected to a reference voltage, the first electrode of the clamping transistor is connected to the second connection terminal, and the second electrode of the clamping transistor is connected to a power supply voltage; wherein a parasitic clamping diode is provided between the control electrode and the first electrode of the clamping transistor, and the parasitic clamping diode is used to chop the signal of the second connection terminal of the coupling control unit so that the variation trend of the DC component of the voltage of the first electrode of the clamping transistor is the same as the variation trend of the envelope amplitude of the radio frequency signal; the voltage of the first electrode of the clamping transistor is provided to the bias terminal as a bias voltage after passing through the coupling control unit.

[0010] Optionally, the clamping transistor is a metal semiconductor field effect transistor or a high electron mobility transistor.

[0011] Optionally, the coupling control unit includes: at least one inductor, or a series-parallel structure of at least one resistor and at least one inductor, or a series-parallel structure of at least one resistor, at least one inductor and at least one capacitor.

[0012] Optionally, the coupling control unit includes: a first resistor and a first inductor; the first resistor and the first inductor are connected in parallel between the first connection end and the second connection end.

[0013] Optionally, the bias circuit further includes: at least one reference voltage generating module; the reference voltage generating module is used to generate the reference voltage, and an output end of the reference voltage generating module is correspondingly connected to a control electrode of at least one of the clamp transistors;

[0014] and / or,

[0015] At least one filter module; one of the filter modules is correspondingly connected to the control electrode of at least one of the clamping transistors.

[0016] Optionally, the radio frequency power amplifier comprises a plurality of amplifiers connected in cascade; the bias circuit comprises a plurality of clamp transistors having the same number as the amplifiers;

[0017] The bias circuit includes a reference voltage generating module, the output end of which is connected to the control electrode of each clamp transistor;

[0018] Alternatively, the bias circuit comprises: a plurality of reference voltage generating modules, and output ends of the plurality of reference voltage generating modules are connected to control electrodes of the plurality of clamp transistors in a one-to-one correspondence.

[0019] Optionally, the reference voltage generating module includes: a second resistor, a third resistor, a fourth resistor, a first transistor and a second transistor;

[0020] The first end of the second resistor is connected to the first electrode of the clamp transistor corresponding to the reference voltage generating module, the second end of the second resistor, the first end of the third resistor and the first electrode of the second transistor are all grounded, the second end of the third resistor is respectively connected to the first electrode of the first transistor and the control electrode of the second transistor, the second electrode of the second transistor is respectively connected to the control electrode of the first transistor and the output end of the reference voltage generating module, the second electrode of the first transistor is respectively connected to the control electrode of the first transistor and the first end of the fourth resistor, and the second end of the fourth resistor is connected to the power supply voltage.

[0021] Optionally, the radio frequency power amplifier comprises a plurality of amplifiers connected in cascade; the bias circuit comprises a plurality of clamp transistors having the same number as the amplifiers;

[0022] The bias circuit includes a filter module, and the filter module is connected to the control electrode of each clamp transistor;

[0023] Alternatively, the bias circuit includes: a plurality of filter modules, connected to the control electrodes of the plurality of clamp transistors in a one-to-one correspondence.

[0024] Optionally, the filtering module includes: a first capacitor; a first end of the first capacitor is connected to a control electrode of the clamping transistor corresponding to the filtering module, and a second end of the first capacitor is grounded.

[0025] In a second aspect, an embodiment of the present invention further provides a radio frequency power amplifier, comprising: at least one stage of amplifier, and a bias circuit as provided in any embodiment of the present invention.

[0026] In the bias circuit provided in the embodiment of the present invention, the RF signal processing link of each amplifier is simplified to include only a coupling control unit and a clamping transistor. More specifically, the RF signal processing link is composed only of a coupling control unit and a parasitic clamping diode in the clamping transistor. This design eliminates the dependence on complex signal chains, can significantly reduce signal processing delays, lay the foundation for broadband operation, and realize a high-speed broadband dynamic bias circuit. When the RF signal enters the processing link, the bias voltage will dynamically increase with the increase of the RF signal envelope amplitude, and dynamically decrease with the decrease of the RF signal envelope amplitude, thereby achieving an accurate dynamic bias effect. This adaptive adjustment mechanism can effectively compensate for the inherent nonlinear characteristics of the RF power amplifier and significantly improve the linearity and efficiency of the RF power amplifier. In summary, the bias circuit provided in the embodiment of the present invention adopts dynamic bias technology to compensate for the intrinsic distortion behavior of the RF power amplifier, optimizes the working state of each amplifier stage by adjusting the bias voltage in real time, and can realize the signal linearization of the RF power amplifier within a broadband range, meet the urgent demand of the communication system for high bandwidth, and help improve the stability and reliability of the communication system.

[0027] It should be understood that the contents described in this section are not intended to identify the key or important features of the embodiments of the present invention, nor are they intended to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0029] Figure 1 is a structural schematic diagram of a radio frequency power amplifier provided by an embodiment of the present invention;

[0030] Figure 2 is a schematic structural diagram of a bias circuit provided by an embodiment of the present invention;

[0031] Figure 3 is a structural schematic diagram of an amplifier provided by an embodiment of the present invention;

[0032] Figure 4 It is a schematic diagram of compensation effect of bias terminal voltage provided by an embodiment of the present invention;

[0033] Figure 5 is a schematic diagram of compensation effect of an AM-AM characteristic provided by an embodiment of the present invention;

[0034] Figure 6 is a schematic structural diagram of another radio frequency power amplifier provided by an embodiment of the present invention;

[0035] Figure 7 is a schematic structural diagram of another bias circuit provided by an embodiment of the present invention;

[0036] Figure 8 is a characteristic curve diagram of a radio frequency power amplifier without using a bias circuit;

[0037] Fig. 9 It is a characteristic curve diagram of a radio frequency power amplifier using the bias circuit provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0038] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work 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 and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions.

[0040] An embodiment of the present invention provides a bias circuit applied to a radio frequency power amplifier. The bias circuit can optimize the working state of the amplifier by adjusting the bias voltage in real time, utilizing the significant influence of the bias voltage of the radio frequency power amplifier on its amplitude and phase transfer characteristics. Figure 1 is a schematic diagram of the structure of a radio frequency power amplifier provided by an embodiment of the present invention. Figure 1, the RF power amplifier PA includes at least one amplifier 10. The RF power amplifier PA is used to amplify the RF input signal RFin to obtain the RF output signal RFout, and the bias terminal G of each amplifier 10 receives a bias voltage to keep the amplifier 10 in linear operation. Each amplifier 10 can adopt any existing structure, which is not specifically limited here. Among them, the RF input signal RFin will form a RF signal transmitted to the bias terminal G after filtering and frequency selection of the internal matching network of the RF power amplifier PA, and the power of the RF signal follows the power change of the RF input signal RFin (or the RF output signal RFout), for example, the power of the RF input signal RFin increases, and the RF signal also increases. The bias circuit 200 provided in the embodiment of the present invention aims to make the bias voltage provided to the bias terminal G of each amplifier 10 follow the dynamic change of the power of the RF signal through an innovative dynamic bias circuit design, for example, increase with the increase of the RF signal power, and decrease with the decrease of the RF signal power, so as to realize accurate compensation of the nonlinear characteristics of the RF power amplifier PA. The structure of the bias circuit 200 is described below.

[0041] See also Figure 1 , the bias circuit 200 includes: a bias control module 20 arranged in one-to-one correspondence with each amplifier 10; Figure 1 For the convenience of explanation, the RF power amplifier PA is exemplarily provided to include a first-stage amplifier 10, and correspondingly, the bias circuit 200 includes a bias control module 20, but this is not intended to limit the present invention.

[0042] The bias control module 20 includes: a coupling control unit 210 and a clamping transistor T0. The first connection terminal N1 of the coupling control unit 210 is connected to the bias terminal G of the amplifier 10 corresponding to the bias control module 20. The coupling control unit 210 is used to filter the RF signal of the bias terminal G and output it through the second connection terminal N2 of the coupling control unit 210. The control electrode of the clamping transistor T0 is connected to the reference voltage VREF, the first electrode of the clamping transistor T0 is connected to the second connection terminal N2, and the second electrode of the clamping transistor T0 is connected to the power supply voltage VDD. Figure 1 At the position circled by the red dotted circle, a parasitic clamping diode is provided between the control electrode and the first electrode of the clamping transistor T0. The parasitic clamping diode is used to chop the signal provided by the second connection terminal N2 of the coupling control unit 210, so that the change trend of the DC component of the voltage of the first electrode of the clamping transistor T0 is the same as the change trend of the envelope amplitude of the RF signal; the voltage of the first electrode of the clamping transistor T0 is provided to the bias terminal G as a bias voltage after passing through the coupling control unit 210.

[0043] Specifically, see Figure 2 , the RF signal at the bias terminal G is as follows Figure 2As shown by the red curve on the right side of the first connection terminal N1 of the coupling control unit 210, the larger the envelope amplitude is, the higher the power of the RF signal is. The bias control module 20 is equivalent to a one-port circuit. The RF signal enters from the first connection terminal N1 of the coupling control unit 210, is processed by the bias control module 20, and forms a bias voltage, which is then output from the first connection terminal N1 of the coupling control unit 210.

[0044] For any bias control module 20, the RF signal enters the bias control module 20 signal chain through the connected bias terminal G, and the entire dynamic bias process begins. The coupling control unit 210 can accurately adjust the attenuation amplitude of the RF signal when it enters the clamping transistor T0. This step is crucial for the subsequent dynamic bias. The coupling control unit 210 is, for example, a filter network with a frequency response, which can control the swing of the RF signal at different frequency points according to actual needs to achieve filtering of the RF signal. The control electrode of the clamping transistor T0 is connected to a stable reference voltage VREF. Under the premise that the control electrode voltage of the clamping transistor T0 is stable, when the RF signal enters the first electrode of the clamping transistor T0 after filtering, under the action of the parasitic clamping diode, the negative half cycle of the RF signal will be chopped. Among them, the parasitic clamping diode is, for example, a Schottky diode. After its rectification and chopping action, most of the negative half cycle of the signal of the first electrode of the clamping transistor T0 is chopped, and the remaining signal waveform is shown as the red curve on the left side of the first connection terminal N1 of the coupling control unit 210. After the above-mentioned chopping action, the equivalent DC level of the first electrode of the clamp transistor T0 is shown as the blue solid line, indicating that the DC component of the voltage of the first electrode of the clamp transistor T0 increases with the increase of the RF signal amplitude and decreases with the decrease of the RF signal amplitude; correspondingly, the DC component (or baseband component) of the voltage difference between the control electrode and the first electrode of the clamp transistor T0 decreases with the increase of the RF signal amplitude, that is, the turn-on voltage of the parasitic clamp diode decreases with the increase of the RF signal amplitude. In summary, the control electrode voltage of the clamp transistor T0 is fixed, and with the effect of the parasitic clamp diode, the change trend of the DC component of the voltage of the first electrode of the clamp transistor T0 can be the same as the change trend of the envelope amplitude of the RF signal. This characteristic is the core mechanism for realizing dynamic adjustment of the bias voltage.

[0045] Exemplarily, the power supply voltage VDD is a stable power supply voltage, for example, the same as the power supply voltage of the amplifier 10, which can be a DC voltage of 5V, 3V or 3.3V. The reference voltage VREF is a stable voltage, which can be provided by a power supply or a reference voltage generating circuit of any structure.

[0046] At present, traditional dynamic bias circuits are usually based on complex control logic and contain long signal processing chains, such as envelope detection circuits, buffer circuits, etc. This design performs well in low-bandwidth applications. However, with the rapid evolution of modern communication standards, the limitations of traditional dynamic bias circuits are becoming increasingly prominent when facing the needs of current high-bandwidth communication systems. The delay and complexity of the signal chain make it difficult for traditional circuits to meet the requirements of 5G and future communication systems for high-speed and broadband signal processing. In addition, with the rapid development of mobile communications and Internet of Things technologies, higher requirements are also placed on the efficiency and linearity of RF power amplifiers. While ensuring signal quality, it is necessary to further improve power efficiency and reduce energy consumption and heat generation.

[0047] In the bias circuit 200 provided in the embodiment of the present invention, the RF signal processing link of each amplifier 10 is simplified to include only the coupling control unit 210 and the clamping transistor T0. More specifically, the RF signal processing link is composed of only the coupling control unit 210 and the parasitic clamping diode in the clamping transistor T0. This design eliminates the dependence on complex signal chains, can significantly reduce signal processing delays, lays the foundation for achieving broadband operation, and realizes a high-speed broadband dynamic bias circuit. When the RF signal enters the processing link, the bias voltage will dynamically increase as the RF signal envelope amplitude increases, and dynamically decrease as the RF signal envelope amplitude decreases, thereby achieving an accurate dynamic bias effect. This adaptive adjustment mechanism can effectively compensate for the inherent nonlinear characteristics of the RF power amplifier PA, and significantly improve the linearity and efficiency of the RF power amplifier PA. To sum up, the bias circuit provided in the embodiment of the present invention adopts dynamic bias technology to compensate for the intrinsic distortion behavior of the RF power amplifier PA, and optimizes the working state of each stage of amplifier 10 by adjusting the bias voltage in real time. It can realize signal linearization of the RF power amplifier PA within a broadband range, meet the urgent demand of the communication system for high bandwidth, and is conducive to improving the stability and reliability of the communication system.

[0048] Figure 3 is a structural schematic diagram of an amplifier provided by an embodiment of the present invention; Figure 4 It is a schematic diagram of compensation effect of bias terminal voltage provided by an embodiment of the present invention; Figure 5 It is a schematic diagram of the compensation effect of an AM-AM characteristic provided by an embodiment of the present invention. Figure 3 In the figure, the input end of the amplifier 10 is represented by Port1, and the output end is represented by Port2; Figure 4 In FIG. 1 , the horizontal axis represents the output power Po of the amplifier 10 (i.e., the power of the radio frequency signal output by the amplifier 10), and the vertical axis represents the voltage VG of the bias terminal G of the amplifier 10; Figure 5In FIG. 1 , the horizontal axis represents the output power Po of the amplifier 10, and the vertical axis represents the AM-AM characteristic of the amplifier 10, which is used to characterize the normalization of the gain. Among them, the AM-AM characteristic mainly focuses on the relationship between the amplitude of the output signal and the amplitude of the input signal. AM-AM distortion refers to the distortion in the amplitude of the output signal and the input signal, that is, amplitude-to-amplitude distortion. Figure 4 and Figure 5 In FIG. 1 , the solid line represents the conventional characteristic of the amplifier 10 when the bias circuit 200 is not used, and the dotted line represents the characteristic obtained after dynamic bias compensation is performed by the bias circuit 200. It can be seen that after the bias compensation of the bias circuit 200, the bias voltage can increase with the increase of the output power of the amplifier 10, and the AM-AM change is more gentle, which effectively improves the linearity of the amplifier 10.

[0049] Continue to see Figure 2 On the basis of the above embodiments, the bias circuit 200 optionally further includes at least one reference voltage generating module 30. The reference voltage generating module 30 is used to generate a reference voltage. The output end of a reference voltage generating module 30 is connected to the control electrode of at least one clamping transistor T0. The reference voltage provided by the reference voltage generating module 30 can be used as a reference bias voltage of the control electrode of the clamping transistor T0 to ensure the stable operation of the entire system.

[0050] When the RF power amplifier includes only one stage amplifier 10, the bias circuit 200 includes one reference voltage generating module 30. When the RF power amplifier includes only multiple stages amplifier 10, the bias circuit 200 includes one or more reference voltage generating modules 30, which can be set according to actual needs, as long as the control electrode of each clamp transistor T0 has a correspondingly connected reference voltage generating module 30.

[0051] Figure 6 FIG. 1 is a schematic diagram of the structure of another radio frequency power amplifier provided by an embodiment of the present invention. Figure 6 Exemplarily, the radio frequency power amplifier PA includes a cascade-connected multi-stage amplifier 10. From the input end to the output end of the radio frequency power amplifier PA, for example, the multi-stage amplifier 10 is connected in series. Figure 6Exemplarily, the RF power amplifier PA includes a three-stage amplifier 10, for example, a pre-driver stage amplifier (Pre DS), a driver stage amplifier (DS) and a power output stage amplifier (PS) in sequence. In the case where the RF power amplifier PA includes a multi-stage amplifier 10, the bias circuit 200 includes a plurality of bias control modules 20 having the same number as the amplifier 10, and correspondingly has a plurality of clamp transistors having the same number as the amplifier 10. In this case, the bias circuit 200 may be configured to include a reference voltage generating module 30, and the output end of the reference voltage generating module 30 is connected to the control electrode of each clamp transistor T0. Alternatively, the bias circuit 200 may also be configured to include: a plurality of reference voltage generating modules 30, and the output ends of the plurality of reference voltage generating modules 30 may be connected to the control electrodes of the plurality of clamp transistors T0 in a one-to-one correspondence.

[0052] On the basis of the above embodiments, the bias circuit 200 may further include at least one filter module 40; one filter module 40 is connected to the control electrode of at least one clamping transistor T0. Due to the effect of the parasitic capacitance of the transistor, there may be a radio frequency signal coupled to the control electrode of the clamping transistor T0. By setting the filter module 40, the high-frequency radio frequency signal can be effectively filtered out, and the stability of the voltage of the control electrode of the clamping transistor T0 can be ensured, so that the reference voltage will not fluctuate up and down due to the influence of the coupled radio frequency signal, which is conducive to improving the accuracy of the bias control.

[0053] When the RF power amplifier includes only one stage amplifier 10, the bias circuit 200 includes one filter module 40. When the RF power amplifier includes only multiple stages amplifier 10, the bias circuit 200 includes one or more filter modules 40, which can be set according to actual needs, as long as the control electrode of each clamping transistor T0 has a correspondingly connected filter module 40.

[0054] See also Figure 6 In the case where the RF power amplifier PA includes a cascade-connected multi-stage amplifier 10, the bias circuit 200 may include a filter module 40, which is connected to the control electrodes of each clamping transistor T0. Alternatively, the bias circuit 200 may include: a plurality of filter modules 40, which are connected to the control electrodes of the plurality of clamping transistors T0 in a one-to-one correspondence.

[0055] The reference voltage generating module 30 and the filtering module 40 may constitute a DC signal processing part in the bias circuit 200 , and may be used to stabilize the potential of the control electrode of the clamping transistor T0 .

[0056] The working principle of each functional module in the bias circuit 200 is exemplarily given in the above-mentioned embodiments. The specific structure of each functional module is exemplarily described below, but it is not intended to limit the present invention.

[0057] In one implementation, the clamp transistor T0 may be a metal semiconductor field effect transistor (MESFET), a high electron mobility transistor (HEMT), or other transistors with a gate-source parasitic diode. The control electrode of the clamp transistor T0 is, for example, a gate, the first electrode is, for example, a source, and the second electrode is, for example, a drain.

[0058] In one embodiment, the coupling control unit 210 is optionally a frequency-dependent filtering attenuation circuit capable of passing direct current, and can control the attenuation amplitude when different frequency points pass through. For example, it includes: at least one inductor connected between the first connection terminal N1 and the second connection terminal N2; or, a series-parallel structure of at least one resistor and at least one inductor connected between the first connection terminal N1 and the second connection terminal N2; or, a series-parallel structure of at least one resistor, at least one inductor and at least one capacitor connected between the first connection terminal N1 and the second connection terminal N2.

[0059] Figure 7 is a schematic diagram of the structure of another bias circuit provided by an embodiment of the present invention. Figure 7 , illustratively, the coupling control unit 210 includes: a first resistor R1 and a first inductor L1; the first resistor R1 and the first inductor L1 are connected in parallel between the first connection terminal N1 and the second connection terminal N2. In this embodiment, the coupling control unit 210 is composed of the first resistor R1 and the first inductor L1, which makes the circuit structure simple, and can accurately control the attenuation amplitude of the RF signal when entering the clamping transistor T0, laying a foundation for subsequent dynamic bias.

[0060] Continue to see Figure 7 In one embodiment, optionally, the reference voltage generating module 30 includes: a second resistor R2, a third resistor R3, a fourth resistor R4, a first transistor T1, and a second transistor T2. The first end of the second resistor R2 is connected to the first electrode of the clamping transistor T0 corresponding to the reference voltage generating module 30, the second end of the second resistor R2, the first end of the third resistor R3, and the first electrode of the second transistor T2 are all grounded, the second end of the third resistor R3 is respectively connected to the first electrode of the first transistor T1 and the control electrode of the second transistor T2, the second electrode of the second transistor T2 is respectively connected to the control electrode of the first transistor T1 and the output end of the reference voltage generating module, the second electrode of the first transistor T1 is respectively connected to the control electrode of the first transistor T1 and the first end of the fourth resistor R4, and the second end of the fourth resistor R4 is connected to the power supply voltage VDD.

[0061] In this embodiment, the reference voltage generation module 30 is composed of a plurality of resistors and transistors, and provides a stable reference voltage for the clamp transistor T0 to ensure the accuracy of the bias control, thereby ensuring the stable operation of the entire system. The structure of the reference voltage generation module 30 is not intended to limit the present invention. In practical applications, other structures capable of outputting a reference voltage may also be used, such as a simple resistor voltage divider to provide a reference voltage.

[0062] Continue to see Figure 7 In one embodiment, the filter module 40 optionally includes: a first capacitor C1; a first end of the first capacitor C1 is connected to the control electrode of the clamp transistor T0 corresponding to the filter module 40, and a second end of the first capacitor C1 is grounded. In this embodiment, the filter module 40 is configured to be composed of one capacitor to simplify the circuit structure.

[0063] In order to verify the bias voltage adjustment effect of the bias circuit provided in the embodiment of the present invention, the inventors conducted simulation verification on the relevant characteristics of the RF power amplifier without the bias circuit and the RF power amplifier with the bias circuit. The verification results can be found in Figure 8 and Fig. 9 .in, Figure 8 Indicates the relevant characteristics of the RF power amplifier without bias circuit. Fig. 9 The characteristics of the radio frequency power amplifier using the bias circuit provided by the embodiment of the present invention are shown. Figure 8 and Fig. 9 In the figure, the horizontal axis is the power of the RF output signal of the RF power amplifier, that is, the output power Pout of the RF power amplifier, in dBm; the left vertical axis represents the gain GAIN of the RF power amplifier, corresponding to the solid line curve; the right vertical axis represents the AM-PM (amplitude to phase change) characteristics of the RF power amplifier, corresponding to the dotted line curve.

[0064] Referring to the verification results, it can be seen that when the bias circuit provided by the embodiment of the present invention is adopted, when the RF signal enters the RF signal processing link through the bias terminal G, the bias voltage will dynamically increase with the increase of the signal envelope amplitude. The nonlinear distortion of the RF power amplifier is significantly suppressed. The gain curve is more linear and the AM-PM change is smoother, which not only improves the signal quality, but also expands the linear operating range of the amplifier. Therefore, the adaptive adjustment mechanism provided by the embodiment of the present invention can effectively compensate for the inherent nonlinear characteristics of the RF power amplifier and significantly improve the linearity and efficiency of the amplifier.

[0065] In summary, the embodiment of the present invention proposes an innovative dynamic bias circuit, whose structure includes a reference voltage generation module 30, a filtering module 40, a coupling control unit 210 and a clamping transistor T0 with a parasitic clamping diode. This combination not only simplifies the circuit structure, but also realizes accurate compensation for the nonlinear characteristics of the RF power amplifier, and can generate a bias voltage that quickly tracks the signal envelope, thereby effectively compensating for the intrinsic distortion of the RF power amplifier, bringing significant performance improvement to the RF power amplifier.

[0066] Specifically, as the output power of the RF power amplifier increases, this circuit can accurately counteract the nonlinear characteristics of amplitude early compression and phase lag by adjusting the bias voltage in real time. This dynamic compensation mechanism not only significantly improves the linearity of the RF power amplifier under high power conditions, but also expands its effective operating range. Therefore, even under strict high-order modulation methods, it can maintain excellent signal quality, effectively reduce the bit error rate, and improve overall communication performance.

[0067] Secondly, the embodiment of the present invention adopts a simplified RF signal processing link design, which greatly reduces the signal processing delay, has a fast response capability, and is conducive to improving the data transmission rate. This enables the bias adjustment to quickly respond to the change of the RF signal envelope, achieve effective operation within a wideband range, and meet the growing bandwidth requirements of modern communication systems. The simplified structure not only reduces the manufacturing cost, but also improves the system reliability, and facilitates integration and large-scale production.

[0068] It is worth emphasizing that the bias circuit provided by the embodiment of the present invention not only improves the overall performance of the RF power amplifier, but also has wide applicability and significant energy-saving effects. It can be applied to various types of RF power amplifiers and is suitable for a variety of application scenarios from mobile terminals to base station equipment, including but not limited to base station transmitters, mobile terminals, and satellite communication equipment. The bias circuit provided by the embodiment of the present invention can significantly improve power efficiency and reduce energy loss and heat generation by keeping the RF power amplifier in linear operation in an area closer to the saturation point. This is not only conducive to extending the battery life of mobile devices, but also reduces the energy consumption of base stations, making an important contribution to green communications.

[0069] The embodiment of the present invention further provides a radio frequency power amplifier, including the bias circuit provided by any embodiment of the present invention, and having corresponding beneficial effects. Figure 1 and Figure 6As shown, the RF power amplifier may include a bias circuit 200 and at least one amplifier 10, and each bias control module 20 in the bias circuit 200 is connected to the bias terminal G of each amplifier 10 in a one-to-one correspondence. The amplifier 10 may adopt any existing structure, which is not limited here. Exemplarily, the RF power amplifier may be applied to a wireless communication system to amplify a weak RF input signal Rfin to obtain an RF output signal RFout with a power level sufficient to drive an antenna.

[0070] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps described in the present invention can be executed in parallel, sequentially or in different orders, as long as the desired results of the technical solution of the present invention can be achieved, and this document does not limit this.

[0071] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A bias circuit, characterized in that: Applicable to a radio frequency power amplifier; the radio frequency power amplifier comprises at least one stage of amplifier; The bias circuit comprises: a bias control module arranged in one-to-one correspondence with each of the amplifiers; The bias control module comprises: A coupling control unit; a first connection end of the coupling control unit is connected to the bias end of the amplifier corresponding to the bias control module; the coupling control unit is used to filter the radio frequency signal of the bias end and output it through the second connection end of the coupling control unit; A clamping transistor; the control electrode of the clamping transistor is connected to a reference voltage, the first electrode of the clamping transistor is connected to the second connection terminal, and the second electrode of the clamping transistor is connected to a power supply voltage; wherein a parasitic clamping diode is provided between the control electrode and the first electrode of the clamping transistor, and the parasitic clamping diode is used to chop the signal of the second connection terminal of the coupling control unit so that the variation trend of the DC component of the voltage of the first electrode of the clamping transistor is the same as the variation trend of the envelope amplitude of the radio frequency signal; the voltage of the first electrode of the clamping transistor is provided to the bias terminal as a bias voltage after passing through the coupling control unit.

2. The bias circuit according to claim 1, characterized in that: The clamping transistor is a metal semiconductor field effect transistor or a high electron mobility transistor.

3. The bias circuit according to claim 1, wherein: The coupling control unit includes: at least one inductor, or a series-parallel structure of at least one resistor and at least one inductor, or a series-parallel structure of at least one resistor, at least one inductor and at least one capacitor.

4. The bias circuit according to claim 1 or 3, characterized in that: The coupling control unit includes: a first resistor and a first inductor; the first resistor and the first inductor are connected in parallel between the first connection end and the second connection end.

5. The bias circuit according to claim 1, wherein: Also includes: at least one reference voltage generating module; The reference voltage generation module is used to generate the reference voltage, and an output end of the reference voltage generation module is correspondingly connected to the control electrode of at least one of the clamp transistors; and / or, at least one filtering module; One of the filter modules is correspondingly connected to the control electrode of at least one of the clamp transistors.

6. The bias circuit according to claim 5, characterized in that: The radio frequency power amplifier comprises a plurality of amplifiers connected in cascade; the bias circuit comprises a plurality of clamp transistors having the same number as the amplifiers; The bias circuit includes a reference voltage generating module, the output end of which is connected to the control electrode of each clamp transistor; Alternatively, the bias circuit comprises: a plurality of reference voltage generating modules, and output ends of the plurality of reference voltage generating modules are connected to control electrodes of the plurality of clamp transistors in a one-to-one correspondence.

7. The bias circuit according to claim 5 or 6, characterized in that: The reference voltage generating module comprises: a second resistor, a third resistor, a fourth resistor, a first transistor and a second transistor; The first end of the second resistor is connected to the first electrode of the clamp transistor corresponding to the reference voltage generating module, the second end of the second resistor, the first end of the third resistor and the first electrode of the second transistor are all grounded, the second end of the third resistor is respectively connected to the first electrode of the first transistor and the control electrode of the second transistor, the second electrode of the second transistor is respectively connected to the control electrode of the first transistor and the output end of the reference voltage generating module, the second electrode of the first transistor is respectively connected to the control electrode of the first transistor and the first end of the fourth resistor, and the second end of the fourth resistor is connected to the power supply voltage.

8. The bias circuit according to claim 5, characterized in that: The radio frequency power amplifier comprises a plurality of amplifiers connected in cascade; the bias circuit comprises a plurality of clamp transistors having the same number as the amplifiers; The bias circuit includes a filter module, and the filter module is connected to the control electrode of each clamp transistor; Alternatively, the bias circuit includes: a plurality of filter modules, connected to the control electrodes of the plurality of clamp transistors in a one-to-one correspondence.

9. The bias circuit according to claim 5 or 8, characterized in that: The filtering module comprises: a first capacitor; a first end of the first capacitor is connected to a control electrode of the clamping transistor corresponding to the filtering module, and a second end of the first capacitor is grounded.

10. A radio frequency power amplifier, characterized in that: include: At least one amplifier stage, and a bias circuit as claimed in any one of claims 1 to 9.

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