Active dynamic biasing circuit of power amplifier, power amplifier circuit and module

Abstract

The invention provides an active dynamic bias circuit of a power amplifier, a power amplifier circuit and a module. The active dynamic bias circuit comprises a control power supply; the bias voltage branch is connected between the control power supply and the grid electrode of the power amplifier and comprises a plurality of voltage division circuit elements which are connected in series, a voltage clamping controlled point is formed between one group of voltage division circuit elements, and a voltage clamping point is formed between the other group of voltage division circuit elements; the voltage clamping branch is connected between the control power supply and the voltage clamping point; the bias switching control branch comprises a switch element, and the control end of the switch element is connected with the radio frequency input end through a blocking capacitor; the switch element is used for being turned on when the radio frequency input signal reaches a set value, the voltage of the voltage clamping point is changed so that the voltage clamping branch can be turned on, the voltage at the voltage clamping point can be clamped at the target value, and therefore the grid voltage of the power amplifier is stable when the radio frequency input signal is larger than the set value.

Description

Technical Field

[0001] The present application relates to the technical field of power amplifiers, and in particular to an active dynamic bias circuit, a power amplifier circuit and a power amplifier module of a power amplifier. Background Art

[0002] GaN power amplifiers are a common type of power amplifier currently, and are usually used in high-frequency, high-power application scenarios. However, GaN power amplifiers themselves have some shortcomings, such as large gain compression and poor linearity, which also limit the application and performance of GaN power amplifiers. Summary of the invention

[0003] In order to solve the existing technical problems, the present application provides an active dynamic bias circuit, a power amplifier circuit and a power amplifier module of a power amplifier that can effectively improve the power and gain of the power amplifier, and is particularly suitable for improving the performance of GaN power amplifiers.

[0004] In a first aspect, an active dynamic bias circuit of a power amplifier is provided, comprising:

[0005] Control power supply;

[0006] A bias voltage branch, connected between the control power supply and the gate of the power amplifier, comprising a plurality of voltage divider circuit elements connected in series, a voltage clamping controlled point formed between one group of voltage divider circuit elements, and a voltage clamping point formed between another group of voltage divider circuit elements;

[0007] A voltage clamping branch, connected between the control power supply and the voltage clamping point;

[0008] A bias switching control branch, comprising a switch element connected between the control power supply, the voltage clamping controlled point and the electrode ground, wherein the control end of the switch element is connected to the radio frequency input end through a DC blocking capacitor, and the radio frequency input signal is fed into the switch element after frequency selection through the DC blocking capacitor;

[0009] The switch element is used to turn on when the RF input signal reaches a set value, change the voltage of the voltage clamping point to make the voltage clamping branch conductive, so that the voltage at the voltage clamping point is clamped at a target size, so that when the RF input signal is greater than the set value, the gate voltage of the power amplifier is stable.

[0010] In a second aspect, a power amplifier circuit is provided, including a power amplifier and an active dynamic bias circuit of the power amplifier described in any embodiment of the present application.

[0011] In a third aspect, a power amplifier module is provided, including a chip and a packaging substrate, wherein the chip or the packaging substrate is provided with a power amplifier circuit as described in any embodiment of the present application.

[0012] The active dynamic bias circuit provided in the above embodiment, through the setting of the bias voltage branch, the voltage clamping branch and the bias switching control branch, uses the DC blocking capacitor in the bias switching control branch to select the frequency of the RF input signal and then feeds it into the control end of the switching element, so that the switching element can be turned on after the RF input signal reaches the set value, and the conduction of the voltage clamping branch is adjusted by the opening of the switching element, so that the voltage at the voltage clamping point can be clamped at the target size. When the RF input signal continues to increase, the gate voltage of the power amplifier can remain stable. Before the switching element is turned on, the control power supply provides a bias voltage to the gate of the power amplifier through the bias voltage branch, so that the gate voltage of the power amplifier can change with the change of the input power, thereby modulating the linearity of the power amplifier to obtain good gain compression performance and linear performance.

[0013] Among them, the active dynamic bias circuit provided in the embodiment of the present application is particularly suitable for applications in high-frequency, high-power GaN power amplifiers, so as to effectively solve the problems of gain compression and poor linearity of the GaN power amplifier.

[0014] The power amplifier circuit and power amplifier module provided in the above embodiments belong to the same concept as the corresponding active dynamic bias circuit embodiment of the power amplifier, and thus have the same technical effects as the corresponding active dynamic bias circuit embodiment of the power amplifier, and will not be described in detail here. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 A block diagram of an active dynamic bias circuit for a power amplifier according to an embodiment.

[0016] Figure 2 is a circuit diagram of an active dynamic bias circuit of a power amplifier in one embodiment.

[0017] Figure 3 for Figure 2 The equivalent circuit diagram of the active dynamic bias circuit of the power amplifier shown in the first working state.

[0018] Figure 4 for Figure 2 The equivalent circuit diagram of the active dynamic bias circuit of the power amplifier shown in the second working state.

[0019] Figure 5 for Figure 2 The equivalent circuit diagram of the active dynamic bias circuit of the power amplifier shown in the third working state.

[0020] Figure 6 A schematic diagram of the change in gate voltage of a power amplifier as input power is provided in an embodiment of the present application.

[0021] Figure 7 A schematic diagram showing how the gain of a power amplifier provided in an embodiment of the present application varies with input power.

[0022] Figure 8 Schematic diagram of the structure of a power amplifier module in one embodiment. DETAILED DESCRIPTION

[0023] The technical solution of the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0024] 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.

[0025] 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.

[0026] It should also be noted that when an element is referred to as being "fixed to" another element, it may be directly on the other element or there may also be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "inside", "outside", "left", "right" and similar expressions used herein are only for the purpose of explanation in conjunction with the embodiments of the accompanying drawings and do not represent the only implementation method.

[0027] Please refer to Figure 1 and Figure 2 An embodiment of the present application provides an active dynamic bias circuit of a power amplifier D3, including: a control power supply U1, a bias voltage branch 11, a voltage clamping branch 12 and a bias switching control branch 13.

[0028] The bias voltage branch 11 is connected between the control power supply U1 and the gate of the power amplifier D3, and includes a plurality of voltage-dividing circuit elements connected in series, a voltage clamping controlled point 131 is formed between one group of voltage-dividing circuit elements, and a voltage clamping point 132 is formed between another group of voltage-dividing circuit elements. The voltage clamping branch 12 is connected between the control power supply U1 and the voltage clamping point 132. The bias switching control branch 13 includes a switch element D1 connected between the control power supply U1, the voltage clamping controlled point 131 and the electrode ground, the control end of the switch element D1 is connected to the RF input end through the DC isolation capacitor C1, and the RF input signal is fed into the switch element D1 after frequency selection through the DC isolation capacitor C1. The switch element D1 is used to turn on when the RF input signal reaches a set value, change the voltage of the voltage clamping point 132 to turn on the voltage clamping branch 12, so that the voltage at the voltage clamping point 132 is clamped at a target value, so that when the RF input signal is greater than the set value, the gate voltage of the power amplifier D3 is stable.

[0029] The control power supply U1 is connected to the gate of the power amplifier D3 through the bias voltage branch 11, and one end connected to the gate of the power amplifier D3 through the bias voltage branch 11 is used as the output end of the active dynamic bias circuit to provide a bias voltage to the gate of the power amplifier D3. In the bias voltage branch 11, different voltage-dividing circuit elements form potential points with different voltages between each other. Along the extension direction of the bias voltage branch 11, the voltage clamping controlled point 131 is located closer to the control power supply U1 than the voltage clamping point 132, and the voltage at the voltage clamping controlled point 131 is higher than the voltage at the voltage clamping point 132.

[0030] The bias switching control branch 13 is set up, and the control end of the switch element D1 is connected to the RF input end through the DC blocking capacitor C1, so that the active dynamic bias circuit can obtain part of the signal at the input of the RF input end, so that the change of the RF input signal can be used as a control signal, and the conduction or disconnection of the bias switching control branch 13 and the voltage clamping branch 12 can be adjusted accordingly, so as to realize the dynamic modulation of the bias voltage provided by the active dynamic bias circuit to the gate of the power amplifier D3.

[0031] In the above embodiment, the active dynamic bias circuit is configured by the bias voltage branch 11, the voltage clamping branch 12 and the bias switching control branch 13. The DC blocking capacitor C1 in the bias switching control branch 13 is used to select the frequency of the RF input signal and then feed it into the control end of the switch element D1, so that the switch element D1 can be turned on after the RF input signal reaches the set value. The conduction of the voltage clamping branch 12 is controlled by the turning on of the switch element D1, so that the voltage at the voltage clamping point 132 can be clamped at the target value. When the RF input signal continues to increase, the gate voltage of the power amplifier D3 can remain stable. Before the switch element D1 is turned on, the control power supply U1 provides a bias voltage to the gate of the power amplifier D3 through the bias voltage branch 11, so that the gate voltage of the power amplifier D3 can change with the change of the input power, thereby modulating the linearity of the power amplifier D3 to obtain good gain compression performance and linear performance.

[0032] In some embodiments, the voltage-dividing circuit element includes a first voltage-dividing resistor R3, a second voltage-dividing resistor R5, and a third voltage-dividing resistor R7 connected in sequence; the voltage clamping controlled point 131 is formed between the first voltage-dividing resistor R3 and the second voltage-dividing resistor R5, and the voltage clamping point 132 is formed between the second voltage-dividing resistor R5 and the third voltage-dividing resistor R7. In this embodiment, the voltage at the voltage clamping point 132 before the voltage clamping branch 12 is turned on can be adjusted by setting the relative sizes of the first voltage-dividing resistor R3, the second voltage-dividing resistor R5, and the third voltage-dividing resistor R7, so as to realize a more stable design for controlling the conduction of the voltage clamping branch 12.

[0033] Optionally, the bias voltage branch 11 further includes an inductor L1 connected between the second voltage-dividing resistor R5 and the third voltage-dividing resistor R7; the voltage clamping point 132 is located at the node where the inductor L1 and the second voltage-dividing resistor R5 are connected. In this embodiment, by adding the inductor L1 connected in series between the second voltage-dividing resistor R5 and the third voltage-dividing resistor R7 forming the voltage clamping point 132, the inductor L1 can store and release electrical energy, thereby limiting the current change and rectifying in the bias voltage branch 11, thereby improving the stability of the voltage clamping point 132.

[0034] In some embodiments, the voltage clamping branch 12 includes a clamping voltage divider resistor R5 and a clamping diode D2 connected in series; the positive electrode of the clamping diode D2 is connected to the voltage clamping point 132, and the negative electrode of the clamping diode D2 is connected to the control power supply U1 through the clamping voltage divider resistor R5. The positive electrode of the clamping diode D2 is connected to the voltage clamping point 132, and the negative electrode is connected to the control power supply U1 through the clamping voltage divider resistor R5. By adjusting the voltage at the voltage clamping point 132, the conduction of the clamping diode D2 can be controlled accordingly. The clamping diode D2 can be used to clamp the voltage at the voltage clamping point 132 in the conduction state. At this time, the voltage clamping point 132 is equivalent to forming a stable virtual voltage U2, so that the bias voltage branch 11 provides a bias voltage of a stable size to the gate of the power amplifier D3, and the gate voltage of the power amplifier D3 no longer continues to increase with the increase of the RF input signal.

[0035] Optionally, the active dynamic bias circuit further includes a grounding capacitor C2 connected to the voltage clamping controlled point 131, and a voltage dividing resistor R6 connected between the node between the clamping voltage dividing resistor R5 and the clamping diode D2 and the electrode ground. The design of the grounding capacitor C2 can filter out the AC interference in the bias voltage branch 11, rectify the voltage loaded on the gate of the power amplifier D3, and improve the voltage stability at the voltage clamping controlled point 131.

[0036] In some embodiments, the bias switching control branch 13 further includes a first resistor R1 and a second resistor R2 connected in series between the control power supply U1 and the electrode ground. The switch element D1 is a field effect transistor, the gate of the field effect transistor is connected to the node between the first resistor R1 and the second resistor R2, and the gate is connected to the RF input terminal through the DC blocking capacitor C1, the drain is connected to the voltage clamping controlled point 131, and the source is connected to the electrode ground. In this embodiment, the switching element D1 adopts a field effect tube with fast switching speed and strong anti-interference ability. Through the design of the relative sizes of the first resistor R1 and the second resistor R2, the gate of the field effect tube can obtain a stable DC voltage division provided by the control power supply U1. In addition, the DC blocking capacitor C1 is connected to the RF input end, and the field effect tube can obtain part of the signal at the RF input end through the DC blocking capacitor C1. The RF input signal is selected by the DC blocking capacitor C1 and then fed into the gate of the field effect tube. The DC voltage division between the first resistor R1 and the second resistor R2 is superimposed on the AC signal voltage fed by the DC blocking capacitor C1 after frequency selection, so as to obtain an operating voltage that can turn off the field effect tube when the RF input signal is a small signal and turn on when the RF input signal is a large signal.

[0037] The active dynamic bias circuit provided in the embodiment of the present application is in three working states respectively by turning off or on the switch element D1 in the bias switching control branch 13 according to the change of the RF input signal.

[0038] See also Figure 3 , is an equivalent circuit diagram of the active dynamic bias circuit in the first working state. The RF input signal at the RF input terminal is less than the set value, the signal fed into the bias switching control branch 13 through the DC blocking capacitor C1 is small, and the switch element D1 is turned off. At this time, the switch element D1 in the bias switching control branch 13 is disconnected. The corresponding equivalent circuit of the active dynamic bias circuit is to provide a bias voltage to the gate of the power amplifier D3 through the bias voltage branch 11. Please refer to Figure 6 and Figure 7 When the input power corresponding to the RF input signal is small, the gate of the power amplifier D3 remains constant and small. At this time, the voltage loaded on the gate of the power amplifier D3 is closer to the bias voltage.

[0039] See also Figure 4 , is an equivalent circuit diagram of the active dynamic bias circuit in the second working state. The RF input signal at the RF input terminal reaches the set value. The AC signal selectively fed into the bias switching control branch 13 through the DC blocking capacitor C1 is superimposed on the control terminal of the switch element D1, so that the switch element D1 is turned on. At this time, the switch element D1 is working in the variable resistance area. The switch element D1 is equivalent to a variable resistor Rd. At this time, the voltage at the voltage clamping controlled point 131 approaches the transistor voltage drop of the switch element D1. The clamping diode D2 in the voltage clamping branch 12 is not turned on yet. The corresponding equivalent circuit of the active dynamic bias circuit is to divide the voltage through the variable resistor Rd, and after rectification by the grounding capacitor C2, it is loaded to the gate of the power amplifier D3 through the bias voltage branch 11, thereby raising the bias voltage of the gate of the power amplifier D3. In an optional example, the power amplifier D3 refers to a GaN power amplifier. Please refer to Figure 6 and Figure 7 When the RF input power at the RF input end increases, the gate of the GaN power amplifier increases linearly with the input power, which improves the gain of the GaN power amplifier in the high power area, slows down the gain compression of the GaN power amplifier, improves the AM-AM performance of the GaN power amplifier, and improves the linearity. At the same time, the modulated gate can adjust the state when the IMD3 (third-order intermodulation) of the GaN power amplifier reaches the minimum value (the "sweet spot" of IMD3), and obtain better IMD3 linear performance.

[0040] See also Figure 5, is an equivalent circuit diagram of the active dynamic bias circuit in the second working state. The RF input signal at the RF input terminal continuously reaches and exceeds the set value, and the switch element D1 is turned on. At this time, the switch element D1 works in the saturation region. When the RF input signal increases, the clamping voltage-dividing resistor R5 and the voltage-dividing resistor R6 are used to divide the voltage and load it to the negative electrode of the clamping diode D2. When the voltage at the voltage clamping point is increased to a level sufficient to turn on the clamping diode D2, the clamping diode D2 is immediately turned on, so that the voltage at the voltage clamping point 132 is clamped at the target level. At this time, due to the clamping effect of the clamping diode D2 at the voltage clamping point 132, a virtual voltage U2 is equivalently formed. When the RF input signal continues to increase in value, the gate voltage of the power amplifier D3 is stable and will not continue to rise. Please refer to Figure 6 and Figure 7 After the clamping diode D2 is turned on, the voltage at the voltage clamping point 132 is clamped at a target level, so that the gate voltage of the power amplifier D3 does not continue to rise.

[0041] In another aspect of the embodiments of the present application, a power amplifier circuit is provided, including a power amplifier D3 and an active dynamic bias circuit of the power amplifier D3 according to any embodiment of the present application.

[0042] In an optional example, the power amplifier D3 is a GaN power amplifier, the power amplifier circuit refers to a GaN power amplifier circuit, the input end of the GaN power amplifier is connected to the input matching, the output end is connected to the output matching, and in the active dynamic bias circuit, the DC blocking capacitor C1 can obtain the RF input signal at the front end of the input matching.

[0043] See also Figure 8 On the other hand, the present application also provides a power amplifier module, which includes a chip 21 and a package substrate 22. The power amplifier circuit provided by the embodiment of the present application can be provided in the chip 21 or in the package substrate 22. The power amplifier circuit can be integrated in the chip 21 or in the package substrate 22, and the power amplifier module can be various types of RF power amplifier products, such as various types of GaN power amplifiers.

[0044] 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.

[0045] 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. An active dynamic bias circuit for a power amplifier, characterized in that: include: Control power supply; A bias voltage branch, connected between the control power supply and the gate of the power amplifier, comprising a plurality of voltage divider circuit elements connected in series, a voltage clamping controlled point formed between one group of voltage divider circuit elements, and a voltage clamping point formed between another group of voltage divider circuit elements; A voltage clamping branch, connected between the control power supply and the voltage clamping point; A bias switching control branch, comprising a switch element connected between the control power supply, the voltage clamping controlled point and the electrode ground, wherein the control end of the switch element is connected to the radio frequency input end through a DC blocking capacitor, and the radio frequency input signal is fed into the switch element after frequency selection through the DC blocking capacitor; The switch element is used to turn on when the RF input signal reaches a set value, change the voltage of the voltage clamping point to make the voltage clamping branch conductive, so that the voltage at the voltage clamping point is clamped at a target size, so that when the RF input signal is greater than the set value, the gate voltage of the power amplifier is stable.

2. The active dynamic bias circuit according to claim 1, characterized in that: The voltage-dividing circuit element comprises a first voltage-dividing resistor, a second voltage-dividing resistor and a third voltage-dividing resistor connected in sequence; The voltage clamping controlled point is formed between the first voltage-dividing resistor and the second voltage-dividing resistor, and the voltage clamping point is formed between the second voltage-dividing resistor and the third voltage-dividing resistor.

3. The active dynamic bias circuit according to claim 2, characterized in that: The bias voltage branch further includes an inductor connected between the second voltage-dividing resistor and the third voltage-dividing resistor; The voltage clamping point is located at a node where the inductor and the second voltage-dividing resistor are connected.

4. The active dynamic bias circuit according to claim 1, characterized in that: The voltage clamping branch includes a clamping voltage dividing resistor and a clamping diode connected in series; The anode of the clamping diode is connected to the voltage clamping point, and the cathode of the clamping diode is connected to the control power supply through the clamping voltage dividing resistor.

5. The active dynamic bias circuit according to claim 4, characterized in that: It also includes a grounding capacitor connected to the voltage clamping controlled point, and a voltage dividing resistor connected between the node between the clamping voltage dividing resistor and the clamping diode and the electrode ground.

6. The active dynamic bias circuit according to claim 1, characterized in that: The bias switching control branch further includes a first resistor and a second resistor connected in series between the control power supply and the electrode ground; The switching element is a field effect transistor, the gate of the field effect transistor is connected to the node between the first resistor and the second resistor, and the gate is connected to the RF input terminal through the DC blocking capacitor, the drain is connected to the voltage clamping controlled point, and the source is connected to the electrode ground.

7. The active dynamic bias circuit according to claim 1, characterized in that: When the RF input signal is less than the set value, the switch element is turned off, and the corresponding equivalent circuit of the active dynamic bias circuit is to provide a bias voltage to the gate of the power amplifier through the bias voltage branch.

8. The active dynamic bias circuit according to claim 1, characterized in that: When the RF input signal reaches a set value, the switch element is turned on, changing the voltage of the voltage clamping point. Before the voltage clamping branch is turned on, the switch element is equivalent to a variable resistor, and the corresponding equivalent circuit of the active dynamic bias circuit is to divide the voltage through the variable resistor and provide a bias voltage to the gate of the power amplifier through the bias voltage branch.

9. A power amplifier circuit, characterized in that: The invention comprises a power amplifier and an active dynamic bias circuit of the power amplifier according to any one of claims 1 to 8.

10. A power amplifier module, characterized in that: It comprises a chip and a packaging substrate, wherein the chip or the packaging substrate is provided with the power amplifier circuit as claimed in claim 9.

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