Power amplifier, power amplifier bias circuit thereof and radio frequency module

Abstract

The invention provides a power amplifier, a power amplifier bias circuit thereof and a radio frequency module, the power amplifier bias circuit comprises a first bias used for being connected with a radio frequency input end of the power amplifier and comprising a thermal coupling tube which is in common ground connection with the power amplifier; the second bias is used for being connected with the radio frequency input end and comprises a cold coupling tube; and the thermal coupling compensation proportion in the thermal coupling tube in the first path of bias and the cold coupling tube in the second path of bias can be adjusted so as to control the gain amplitude of the electric heating loop.

Description

Technical Field

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

[0002] Power amplifiers (PA) are widely used in various fields such as communications, audio, lasers, radars, etc. For example, wireless local area networks (WLAN) share the same frequency bandwidth between transmitters (Tx) and receivers (Rx), which means that during the communication process, transmission and reception cannot be performed at the same frequency at the same time, otherwise signal conflicts will occur. For this reason, WLAN systems use time division duplexing (TDD), which is a method of separating the transmission and reception signals in time.

[0003] In TDD mode, the WLAN system controls the transmission and reception of signals through a fast switching switch. When the receiver (Rx) is receiving a signal, the transmitter (Tx) is turned off to prevent the transmission signal from interfering with the reception signal. Conversely, when Tx is sending a signal, Rx is turned off. This fast switching is usually implemented by a dedicated switch circuit in hardware, which can complete the switch from transmission to reception or from reception to transmission in microseconds. PA is a key part of the wireless communication system. The WLAN system needs to work in TDD mode. PA must be able to work stably in both static (i.e., transmission or reception remains unchanged) and dynamic (i.e., transmission and reception are frequently switched) operation modes, which means that PA needs to meet both static error vector magnitude (SEVM) and dynamic error vector magnitude (DEVM). It takes time for PA to go from turning on to a stable gain state. This period of thermal steady-state response time after turning on is the main reason why the dynamic error vector magnitude is worse than the static error vector magnitude. At present, there is a lack of effective solutions to optimize the DEVM of PA. Summary of the invention

[0004] In order to solve the existing technical problems, the present application provides a power amplifier bias circuit, a power amplifier and a radio frequency module that can optimize the DEVM of a PA.

[0005] In a first aspect, an embodiment of the present application provides a power amplifier bias circuit, comprising: a first bias path, used to be connected to a radio frequency input terminal of a power amplifier, and comprising a thermal coupling tube connected to a common ground with the power amplifier;

[0006] A second bias path, used to be connected to the RF input terminal, comprising a cold coupling tube;

[0007] The thermal coupling compensation ratios in the thermal coupling tube in the first bias path and the cold coupling tube in the second bias path are adjustable to control the amplitude of the electrothermal loop gain.

[0008] In a second aspect, a bias power circuit is provided, comprising:

[0009] A first bias path, used to be connected to a radio frequency input terminal of a power amplifier, and comprising a thermal coupling tube connected to the power amplifier;

[0010] A second bias path, used to be connected to the RF input terminal, comprising a cold coupling tube;

[0011] The distance between the thermocoupler and the power amplifier die is smaller than the distance between the cold coupler and the power amplifier die, and the thermal coupling compensation ratios in the thermocoupler in the first bias path and the cold coupler in the second bias path are adjustable to control the amplitude of the electrothermal loop gain.

[0012] In a third aspect, a power amplifier is provided, comprising:

[0013] It comprises a power amplifier die and a power amplifier bias circuit as described in any embodiment of the present application;

[0014] The power amplifier die includes a first die array and a second die array which are symmetrically arranged, and the thermal coupling tube is located on a center line between the first die array and the second die array.

[0015] In a fourth aspect, a radio frequency module is provided, comprising the power amplifier described in any embodiment of the present application.

[0016] The power amplifier bias circuit provided in the above embodiment has two bias paths, namely, a first bias path and a second bias path. The first bias path includes a thermocouple connected to the power amplifier, and the second bias path includes a cold coupler. The thermocouple and the cold coupler form different ratios of the thermocouple bias and the cold coupler bias due to the difference in whether they are connected to the common ground of the power amplifier tube core or the difference in the relative size of the physical distance between the thermocouple and the power amplifier tube core. The ratio of the thermocouple bias and the cold coupler bias can be adjusted, so that the thermal coupling compensation ratio of the thermocouple in the first bias path and the cold coupler in the second bias path can be adjusted to control the amplitude of the electrothermal loop gain. Therefore, by adjusting the thermal coupling compensation ratio of the thermocouple and the cold coupler, accurate compensation of the thermal coupling coefficient can be achieved, the thermal transient response time of the power amplifier can be shortened, and the DEVM of the power amplifier can be improved.

[0017] The power amplifier and RF module provided in the above embodiments belong to the same concept as the corresponding power amplifier bias circuit embodiments, and thus have the same technical effects as the corresponding power amplifier bias circuit embodiments, which will not be described in detail here. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 A graph created for the thermal transient response of a single biased PA bias circuit.

[0019] Figure 2 The circuit topology diagram of the power amplifier bias circuit with single-channel bias.

[0020] Figure 3 for Figure 2 The temperature compensation schematic diagram of the power amplifier bias circuit is shown.

[0021] Figure 4 for Figure 2 Schematic diagram of thermal coupling compensation of the power amplifier bias circuit shown.

[0022] Figure 5 A schematic diagram of the circuit principle of a power amplifier bias circuit provided in one embodiment of the present application.

[0023] Figure 6 A circuit topology diagram of a power amplifier bias circuit provided in one embodiment of the present application.

[0024] Figure 7 A schematic diagram of the layout of a power amplifier bias circuit provided in one embodiment of the present application.

[0025] Figure 8 A schematic diagram of the actual layout of a power amplifier bias circuit provided in one embodiment of the present application.

[0026] Fig. 9 A curve chart established for the thermal transient response of the power amplifier bias circuit provided in an embodiment of the present application.

[0027] Fig.10 A schematic diagram of the effect of the circuit loop gain of the power amplifier bias circuit provided in an embodiment of the present application. DETAILED DESCRIPTION

[0028] The technical solution of the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0029] In order to make the purpose, technical solutions and advantages of the present application clearer, the present application will be further described in detail below in conjunction with the accompanying drawings. The described embodiments should not be regarded as limiting the present application. All other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of this application.

[0030] In the following description, the expression "some embodiments" is involved, which describes a subset of all possible embodiments. It should be noted that "some embodiments" may be the same subset or different subsets of all possible embodiments, and may be combined with each other without conflict.

[0031] In the following description, the terms "first, second, third" involved are merely used to distinguish similar objects and do not represent a specific ordering of the objects. It can be understood that "first, second, third" can be interchanged with a specific order or sequence where permitted, so that the embodiments of the present application described herein can be implemented in an order other than that illustrated or described herein.

[0032] In studying how to improve the dynamic error vector magnitude (DEVM) of a power amplifier (PA), the inventors of the present application conducted the following research on factors affecting the DEVM of the PA.

[0033] like Figure 1 As shown, the inventors analyzed the thermal transient response settling time of a power amplifier of a single-path biased power amplifier bias circuit. Thermal transient response refers to the response characteristics of a power amplifier when subjected to a sudden temperature change. Specifically, when a power amplifier experiences a temperature change in a short period of time, its output performance will be affected, and this effect is called thermal transient response.

[0034] The power amplifier bias circuit for single-channel biasing can be an adaptive active linear bias structure, such as Figure 2 As shown, it uses two transistors Q N1 , Q N2 The current mirror structure can be formed by adjusting the ratio of the emitter areas of the two transistors to accurately control the current replication or amplification ratio. N1 The base of transistor Q N2 The function of the inductor DcFeed connected in series between the base and the RF signal is to prevent the RF signal from leaking into the bias circuit. It can effectively block the path of the RF signal entering the bias circuit. The current limiting resistor R N2 The role of the transistor is to enhance the stability of the power amplifier and adjust the linearity performance. N2 The emitter of Bypass Ground, the first bypass capacitor C Bypass It can prevent the RF signal from leaking into the bias circuit, effectively cut off the path of the RF signal entering the bias circuit, and the transistor Q N1 The base and emitter are connected via a second bypass capacitor C be grounded, since transistor Q N1 For a transistor with negative temperature feedback, it needs to share the ground with the power tube PA. The RF signal may leak from the emitter of the power tube PA. The second bypass capacitor C be These leaked RF signals can be effectively bypassed to ground to prevent them from interfering with the bias circuit.

[0035] See also Figure 3The temperature compensation principle of the single-channel bias amplifier bias circuit is: when the input signal increases and the core temperature of the power tube PA rises, the base-emitter junction voltage V be The base current of the power tube PA increases. At the same time, the transistor Q used to provide temperature negative feedback N1 The base-emitter junction voltage V be It also decreases as the temperature rises, causing the current flowing to the transistor Q N1 The base current increases due to the transistor Q N2 The emitter current remains unchanged, which means that the current flowing through the current limiting resistor R N2 The current decreases accordingly, compensating for the increase in the base current of the power tube PA caused by the increase in temperature.

[0036] See also Figure 4 , schematic diagram of thermal coupling compensation of power amplifier bias circuit, transistor Q N1 For thermocouples, based on Figure 3 From the temperature compensation principle shown, it can be seen that the thermocouple can compensate for the thermal transient response time of the power tube PA. Adjusting the distance between the thermocouple and the power tube PA can change the thermal coupling coefficient and the degree of compensation. However, it is difficult to quantify the influence of a single thermocouple on the thermal coupling coefficient, and it is difficult to achieve accurate compensation.

[0037] Based on this, the inventor of the present application proposes a design idea of ​​a dual-path bias power amplifier bias circuit, using a dual-path bias including a thermocoupler and a cold-coupler, respectively, by changing the ratio of the thermocoupler bias to the cold-coupler bias, according to the influence of different ratios of the thermocoupler bias to the cold-coupler bias on the thermal coupling compensation, to quantify the influence of the ratio of the thermocoupler bias to the cold-coupler bias on the thermal coupling coefficient, so as to facilitate more accurate compensation. In other words, there is no need to measure the corresponding relationship between the thermocoupler bias and the thermal coupling coefficient separately, or to measure the corresponding relationship between the cold-coupler bias and the thermal coupling coefficient separately, but by obtaining the influence of the change in the ratio of the thermocoupler bias to the cold-coupler bias on the thermal coupling coefficient, and by changing the ratio of the thermocoupler bias to the cold-coupler bias, accurate compensation adjustment can be achieved.

[0038] See also Figures 5 and 6 The dual-path bias power amplifier bias circuit provided in one embodiment of the present application comprises: a first bias path 11, which is used to connect to the radio frequency input terminal RFin of the power amplifier, and comprises a thermal coupling tube Hot Q connected to the common ground of the power amplifier N1 The second bias circuit 12 is used to connect to the RF input terminal RFin, including a cold coupling tube Cold Q N1 ; The first bias 11 thermocouple Hot Q N1 And the second bias 12 cold coupling tube Cold Q N1The thermal coupling compensation ratio in the circuit can be adjusted to control the magnitude of the electrothermal loop gain.

[0039] In the above embodiment, the power amplifier bias circuit is provided with two bias paths, namely, the first bias path 11 and the second bias path 12. The first bias path 11 includes a thermal coupling tube Hot Q connected to the common ground of the power amplifier. N1 The second bias circuit 12 includes a cold coupling tube Cold Q N1 , using the first bias 11 in the thermocouple tube Hot Q N1 And the second bias 12 cold coupling tube Cold Q N1 The thermal coupling compensation ratio can be adjusted to control the amplitude of the electrothermal loop gain, so that the thermal coupling tube Hot Q N1 and cold coupling tube Cold Q N1 The thermal coupling compensation ratio can achieve accurate compensation of the thermal coupling coefficient, shorten the thermal transient response time of the power amplifier, and improve the DEVM of the power amplifier.

[0040] It should be noted that the first bias 11 thermal coupling tube Hot Q N1 And the second bias 12 cold coupling tube Cold Q N1 In an optional example, in the implementation scheme of bias adjustment for the power amplifier, the first bias 11 includes a thermal coupling tube Hot Q N1 Closed, while the second bias 12 cold coupling tube Cold Q N1 Open, the bias is entirely provided by the first bias 11 in the first limit case; and the thermal coupling tube Hot Q in the first bias 11 N1 Open, and the second bias 12 cold coupling tube Cold Q N1 Closed, the second extreme case where the bias is entirely provided by the second bias 12 .

[0041] In some embodiments, the thermocouple Hot Q N1 The distance between the power amplifier core Q is smaller than the cold coupling tube ColdQ N1 The distance between the power amplifier core Q. A power amplifier is a transistor that amplifies the input signal to a larger voltage, current or power level to drive a larger load or generate a larger output power, such as a triode, MOS (field effect transistor), etc. N1 , refers to the transistor that establishes thermodynamic equilibrium with the power amplifier core Q through heat flow exchange, the thermal coupling tube Hot Q N1 When the current flows through the device or the interconnection point, heat is generated and transferred to the entire substrate of the power amplifier. In this way, the heat can be transferred between the two devices to achieve thermal coupling.N1 , refers to a transistor that effectively transfers and dissipates heat from the power amplifier die Q to maintain the normal temperature of the power amplifier die Q. The working principle of cold coupling can rely on physical principles such as heat conduction, convection and radiation to achieve thermal decoupling. In this embodiment, a thermal coupling tube Hot Q is set N1 The closer the distance to the power amplifier core Q, the more effective it is to change the thermal coupling coefficient and compensation degree, thereby increasing the hot Q of the thermal coupling tube. N1 Thermal coupling compensation for power amplifiers.

[0042] Please refer to Figure 7 and Figure 8 , optional, thermocouple Hot Q N1 Located on the central axis between the symmetrically arranged power amplifier tube cores Q. In order to increase the amplification factor, the power amplifier usually includes multiple parallel power amplifier tube cores Q. In the layout of the power amplifier, the multiple parallel power amplifier tube cores Q are divided into two parts, which are symmetrically arranged on the tube core substrate, and the thermal coupling tube Hot Q N1 It is set on the central axis between the power amplifier tube core Q, which can ensure the thermal coupling tube HotQ N1 The effect on thermal coupling compensation of the power amplifier die Q is the same.

[0043] In some embodiments, the first bias path 11 also includes a thermal coupling tube Hot Q N1 The first transistor Q1 forming the current mirror structure and connected to the hot coupling tube Hot Q N1 The first bias current limiting branch is between the base and the radio frequency input terminal RFin; the first bias current limiting branch includes a first current limiting resistor R1, a first inductor L1 and a second current limiting resistor R2 connected in series in sequence; a thermal coupling tube Hot Q N1 The collector of the first transistor Q1 is connected to the first reference current source Iref1, and the emitter is connected to the power amplifier; the collector of the first transistor Q1 is connected to the bias voltage source Vcc, and the emitter is connected to the first node between the first current limiting resistor R1 and the first inductor L1, and the first node is grounded through the first bypass capacitor C1. N1 The first transistor Q1 forms a current mirror structure. By adjusting the ratio of the emitter areas of the two transistors in the first bias 11, the current replication or amplification ratio can be accurately controlled. In the first bias current limiting branch, the first current limiting resistor R1 and the second current limiting resistor R2 can enhance the thermal stability and adjustment linearity of the power amplifier. The first bypass capacitor C1 and the first inductor L1 can both prevent the RF signal from leaking into the bias circuit and effectively cut off the path of the RF signal into the first bias 11. Optionally, the thermal coupling tube Hot Q N1A third bypass capacitor C3 is connected in series between the base and emitter of the thermocouple Hot Q. The third bypass capacitor C3 can prevent the RF signal from N1 The emitter leakage connected to the power amplifier ground prevents interference with the bias circuit.

[0044] Optionally, the circuit topology structure of the second bias path 12 is the same as the circuit topology structure of the first bias path 11. Specifically, the second bias path 12 also includes a cold coupling tube Cold Q N1 The second transistor Q2 forming the current mirror structure is connected to the cold coupling tube Cold Q N1 The second current branch between the base and the RF input terminal RFin; the second bias current limiting branch includes a third current limiting resistor R3, a second inductor L2 and a fourth current limiting resistor R4 connected in series in sequence; a cold coupling tube Cold Q N1 The collector of the second transistor Q2 is connected to the second reference current source Iref2, and the emitter is grounded; the collector of the second transistor Q2 is connected to the bias voltage source Vcc, and the emitter is connected to the second node between the third current limiting resistor R3 and the second inductor L2, and the second node is grounded through the second bypass capacitor C2. N1 The second transistor Q2 forms a current mirror structure. By adjusting the ratio of the emitter areas of the two transistors in the second bias 12, the current replication or amplification ratio can be accurately controlled. In the second bias current limiting branch, the third current limiting resistor R3 and the fourth current limiting resistor R4 can enhance the thermal stability and adjustment linearity of the power amplifier. The second bypass capacitor C2 and the second inductor L2 can both prevent the RF signal from leaking into the bias circuit and effectively cut off the path of the RF signal into the second bias 12. Optionally, the cold coupling tube Cold Q N1 A fourth bypass capacitor C4 is connected in series between the base and the emitter of , and the fourth bypass capacitor C4 can effectively bypass the leaked RF signal to the ground.

[0045] In the above embodiment, the power amplifier thermal coupling tube Hot Q N1 and cold coupling tube Cold Q N1 There are two bias paths. The first bias path uses a thermal coupling tube Hot Q in 11. N1 Placed in the middle of the power amplifier core Q, the thermal coupling tube Hot Q N1 Closer to the power amplifier core Q, it is called hot pipe bias. The second bias 12 uses the cold coupling tube Cold Q N1 Relatively far away from the power amplifier tube core Q setting, cold coupling tube Cold Q N1 The distance from the power amplifier core Q is far, which is called cold tube bias. In this way, the electric thermal compensation of the power amplifier is divided into two paths. The hot pipe bias will make the hot Q of the thermocouple tube N1Placed in the middle of the power amplifier core Q to achieve thermal coupling, the cold tube bias will cold coupler Cold Q N1 Place it away from the power amplifier core Q to achieve thermal decoupling, use the hot pipe bias and cold pipe bias to achieve temperature compensation, and adjust the bias ratio of the hot pipe bias and the cold pipe bias to quantitatively determine the hot Q of the thermocouple tube. N1 and cold coupling tube Cold Q N1 Compensation ratio for thermal coupling coefficient.

[0046] In some embodiments, the thermocouple Hot Q N1 and cold coupling tube Cold Q N1 The thermal coupling compensation ratio of the thermal coupling tube Hot Q is adjusted based on at least one of the following: the ratio of the first reference current source Iref1 to the second reference current source Iref2; N1 The distance between the power amplifier tube core Q and the cold coupling tube Cold Q N1 In this embodiment, the bias ratio of the first bias 11 and the second bias 12 can control the distance between the thermal coupling tube Hot Q and the power amplifier tube Q. N1 and cold coupling tube Cold Q N1 The influence on the amplitude of the electrothermal loop gain can be adjusted by controlling the ratio of the first reference current source Iref1 and the second reference current source Iref2, or by changing the distance between the thermocoupler Hot QN1 and the cold coupler Cold QN1 and the power amplifier die Q. In an optional specific example, by adjusting the first reference current source Iref1 of the first bias path 11 and the second reference current source Iref2 of the second bias path 12, the thermocoupler Hot QN1 can be adjusted. N1 and cold coupling tube Cold Q N1 Accurate compensation of the thermal coupling coefficient shortens the thermal transient response time of the power amplifier and improves DEVM.

[0047] See also Fig. 9 , respectively represent the thermal coupling tube Hot Q N1 The first bias 11 and the cold coupling tube Cold Q N1 In the second bias path 12, the influence of the change of the first reference current source Iref1 and the second reference current source Iref2 on the thermal steady-state response, Fig.10 The gain of the electric heating loop changes with the moment the power amplifier is turned on, and the gain of the power amplifier changes due to the influence of the bias. Fig. 9 and Fig.10 The electrothermal loop gain increases with the cold coupling tube Cold Q N1As the second reference current source Iref2 in the second bias path 12 increases, its change curve tends to be upward, and the loop gain increases. Conversely, as the thermal coupling tube HotQ N1 When the first reference current source Iref1 in the first bias path 11 increases, its change curve tends to be downward, and the loop gain decreases.

[0048] It should be noted that, under the technical teaching of quantifying the influence of the ratio of the hot coupling tube bias to the cold coupling tube bias on the thermal coupling coefficient provided in the embodiments of the present application, various methods that can change the Hot Q coefficient of the hot coupling tube can be used. N1 and cold coupling tube Cold Q N1 The implementation method of the ratio of the bias contribution belongs to the protection scope of the present application. For example, on the other hand, the present application provides a power amplifier bias circuit, including: a first bias 11, which is used to connect to the radio frequency input terminal RFin of the power amplifier, including a thermal coupling tube Hot Q connected to the power amplifier N1 The second bias 12 is used to connect to the RF input terminal RFin, including a cold coupling tube ColdQ N1 ; The thermal coupling tube Hot Q N1 The distance between the power amplifier core Q is smaller than the cold coupling tube Cold Q N1 The distance between the power amplifier tube core Q, the first bias 11 thermal coupling tube Hot Q N1 And the second bias 12 cold coupling tube Cold Q N1 The thermal coupling compensation ratio in the circuit can be adjusted to control the magnitude of the electrothermal loop gain. N1 Relative to the distance between the power amplifier die and the cold Q of the cold coupling tube N1 By adjusting the relative size of the distance between the power amplifier tube cores, the variation range of the ratio of the thermal coupling tube bias to the cold coupling tube bias can be changed, and the degree of influence of the changes of the two on the thermal coupling compensation ratio can also be changed accordingly.

[0049] In an alternative example, the thermocouple Hot Q N1 Set in the middle of the power amplifier tube core Q, and the cold coupling tube Cold Q N1 Keep away from the power amplifier core Q setting, thermal coupling tube Hot Q N1 Distance relative to the power amplifier core Q and cold coupling tube Cold Q N1 As the ratio of the distance to the power amplifier die Q decreases, the external current source for adjusting the two biases can be increased to change the degree of influence on the thermal coupling compensation ratio.

[0050] The power amplifier bias circuit provided in the above embodiment provides two bias paths for the power amplifier, one of which is a thermal coupling tube Hot Q N1Set in the middle of the power amplifier tube core Q to achieve thermal coupling, and the other cold coupling tube Cold Q N1 The Q setting is far away from the power amplifier die to achieve thermal decoupling. By adjusting the two biased external current sources, the hot coupling tube Hot QN1 and the cold coupling tube Cold Q can be controlled. N1 The proportion of the bias contribution is used to quantify the influence of the ratio of the two biases on the thermal coupling coefficient, so as to adjust the ratio of the two biases to achieve accurate compensation of the thermal coupling coefficient, thereby achieving accurate compensation of the thermal transient response time of the power amplifier and improving DEVM.

[0051] In an optional example, the power amplifier bias circuit adjusts the bias of the power amplifier tube by adding a first bias thermocouple tube Hot Q N1 The weight of the first bias 11 thermal coupling tube Hot Q is reduced. N1 The weight of the second bias circuit is increased by 12 cold-coupled tubes Cold Q N1 The weight can prevent the power amplifier die from overheating and affecting performance.

[0052] In another aspect, the present invention further provides a power amplifier, including a power amplifier die Q and a power amplifier bias circuit according to any embodiment of the present invention; the power amplifier die Q includes a first die array Q11 and a second die array Q12 which are symmetrically arranged, a thermal coupling tube Hot Q N1 Located on the center line between the first die array Q11 and the second die array Q12.

[0053] The circuit topology of the power amplifier tube core Q includes a plurality of tube cores connected in parallel, and is divided into two parts, a first tube core array Q11 and a second tube core array Q12, which are spaced apart and symmetrically arranged in the actual layout of the tube core substrate, so as to improve the output power. N1 Set on the center line between the first tube die array Q11 and the second tube die array Q12, and the distance between the first tube die array Q11 and the second tube die array Q12 is equal. N1 The degree of thermal coupling compensation for the first die array Q11 and the second die array Q12 is equal.

[0054] Optionally, the power amplifier bias circuit and the power amplifier die Q are arranged on the same semiconductor chip, which can simplify the overall process and improve the matching and stability of the circuit.

[0055] On the other hand, an embodiment of the present application further provides a radio frequency module that can be applied to a wireless communication system or a wireless local area network. The radio frequency module includes a power amplifier of any embodiment of the present application to achieve control of receiving, transmitting, and amplifying radio frequency signals.

[0056] It should be noted that, in this article, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the existence of other identical elements in the process, method, article or device including the element.

[0057] The above are only specific implementations of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A power amplifier bias circuit, characterized in that: include: A first bias path, used to be connected to a radio frequency input terminal of a power amplifier, and comprising a thermal coupling tube connected to a common ground with the power amplifier; A second bias path, used to be connected to the RF input terminal, comprising a cold coupling tube; The thermal coupling compensation ratios in the thermal coupling tube in the first bias path and the cold coupling tube in the second bias path are adjustable to control the amplitude of the electrothermal loop gain.

2. The power amplifier bias circuit according to claim 1, characterized in that: The distance between the thermal coupling tube and the power amplifier tube core is smaller than the distance between the cold coupling tube and the power amplifier tube core.

3. The power amplifier bias circuit according to claim 2, characterized in that: The thermocouple is located on the central axis between the symmetrically arranged power amplifier tube cores.

4. The power amplifier bias circuit according to claim 1, characterized in that: The first bias path also includes a first transistor forming a current mirror structure with the thermocoupler and a first bias current limiting branch connected between the base of the thermocoupler and the RF input terminal; The first bias current limiting branch includes a first current limiting resistor, a first inductor and a second current limiting resistor connected in series in sequence; The collector of the thermocouple is connected to the first reference current source, and the emitter is connected to the power amplifier in common ground; The collector of the first transistor is connected to a bias voltage source, the emitter is connected to a first node between the first current limiting resistor and the first inductor, and the first node is grounded through a first bypass capacitor.

5. The power amplifier bias circuit according to claim 4, characterized in that: The second bias path also includes a second transistor forming a current mirror structure with the cold coupling tube and a second current branch connected between the base of the cold coupling tube and the RF input terminal; The second bias current limiting branch comprises a third current limiting resistor, a second inductor and a fourth current limiting resistor connected in series in sequence; The collector of the cold coupling tube is connected to the second reference current source, and the emitter is grounded; The collector of the second transistor is connected to a bias voltage source, the emitter is connected to a second node between the third current limiting resistor and the second inductor, and the second node is grounded through a second bypass capacitor.

6. The power amplifier bias circuit according to claim 5, characterized in that: A third bypass capacitor is connected in series between the base and emitter of the thermocouple; and / or, A fourth bypass capacitor is connected in series between the base and emitter of the cold coupling tube; and / or, The thermal coupling compensation ratio of the thermocoupler and the cold coupler is adjusted based on at least one of the following: the ratio of the first reference current source to the second reference current source; the ratio of the distance between the thermocoupler and the power amplifier die to the distance between the cold coupler and the power amplifier die.

7. A power amplifier bias circuit, characterized in that: include: A first bias path, used to be connected to a radio frequency input terminal of a power amplifier, and comprising a thermal coupling tube connected to the power amplifier; A second bias path, used to be connected to the RF input terminal, comprising a cold coupling tube; The distance between the thermocoupler and the power amplifier die is smaller than the distance between the cold coupler and the power amplifier die, and the thermal coupling compensation ratios in the thermocoupler in the first bias path and the cold coupler in the second bias path are adjustable to control the amplitude of the electrothermal loop gain.

8. A power amplifier, characterized in that: It comprises a power amplifier die and a power amplifier bias circuit as claimed in any one of claims 1 to 7.

9. The power amplifier according to claim 8, characterized in that: The power amplifier bias circuit and the power amplifier die are arranged on the same semiconductor chip; and / or, The power amplifier die includes a first die array and a second die array which are symmetrically arranged, and the thermal coupling tube is located on a center line between the first die array and the second die array.

10. A radio frequency module, characterized in that: Comprising a power amplifier as claimed in claim 8 or 9.

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