Radio frequency power amplification circuit and radio frequency biasing circuit for improving temperature stability

Abstract

The invention relates to a radio frequency power amplification circuit and a radio frequency biasing circuit for improving temperature stability, and relates to the technical field of radio frequency power amplifiers. The radio frequency bias circuit comprises a second bias voltage driving buffer circuit, a second voltage regulation circuit and a second filter circuit, the second voltage regulation circuit comprises a second NPN triode Q2, a third NPN triode Q3, a fourth NPN triode Q4, a second resistor R2, a third resistor R3, a fourth resistor R4, a sixth resistor R6 and a seventh resistor R7, and for the fourth NPN triode Q4, the fourth NPN triode Q4, the third NPN triode Q3, the fourth NPN triode Q4, the fourth NPN triode Q5 and the fourth NPN triode Q6 are connected in series. The emitter electrode is connected to the base electrode of the second NPN triode Q2, and the base electrode and the collector electrode are connected to the first power supply VCC1 through a seventh resistor R7 after being short-circuited. Compared with the prior art, the influence caused by the temperature change is reduced, so that the output power of the radio frequency power amplifier under the condition of fixed input signal power is stabilized within a smaller range along with the change of the environment temperature.

Description

Technical Field

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

[0002] The RF power amplifier circuit includes an RF power amplifier and its matching circuit, wherein the matching circuit includes an RF bias circuit. The function of the RF bias circuit is to power the RF power amplifier in the RF power amplifier circuit through the bias circuit output terminal. The RF power amplifier is composed of a single or multiple NPN transistors directly connected in parallel. When the voltage at the bias circuit output terminal increases, the static voltage of the RF power amplifier also increases, and vice versa.

[0003] However, when using a traditional RF bias circuit, the output power of the RF power amplifier will decrease as the ambient temperature increases. In extreme cases, the RF power amplifier may be over-driven and fail. Summary of the invention

[0004] The technical problem to be solved by the present application is to provide a radio frequency power amplifier circuit and a radio frequency bias circuit for improving temperature stability, which have the characteristics that the output power of the radio frequency power amplifier under the condition of fixed input signal power can be stabilized within a smaller range as the ambient temperature changes.

[0005] In a first aspect, an embodiment provides a radio frequency power amplifier circuit for improving temperature stability, including a radio frequency power amplifier PA and a matching circuit thereof, wherein the matching circuit includes an input matching circuit IMN, an output matching circuit OMN and a radio frequency bias circuit; wherein the input end of the radio frequency power amplifier PA is connected to a radio frequency signal input end IN through the input matching circuit IMN, and is connected to a base power supply of a transistor in the radio frequency power amplifier PA through the radio frequency bias circuit; the output end of the radio frequency power amplifier PA is connected to a radio frequency signal output end OUT through the output matching circuit OMN; The RF bias circuit includes a second bias voltage driving buffer circuit, a second voltage regulating circuit and a second filtering circuit; the second bias voltage driving buffer circuit includes a first NPN transistor Q1, the second filtering circuit is used to filter out the RF signal entering the first NPN transistor Q1, and the second voltage regulating circuit is used to regulate the voltage on the base of the first NPN transistor Q1; The second voltage regulating circuit includes a second NPN transistor Q2, a third NPN transistor Q3, a fourth NPN transistor Q4, a second resistor R2, a third resistor R3, a fourth resistor R4, a sixth resistor R6 and a seventh resistor R7; wherein, for the second NPN transistor Q2, the collector is connected to the collector of the first NPN transistor Q1, the emitter is connected to the base of the third NPN transistor Q3 through the fourth resistor R4, and the base is connected to the first power supply VCC1 through the sixth resistor R6; for the third NPN transistor Q3, the base is grounded through the third resistor R3, the emitter is grounded through the second resistor R2, and the collector is connected to the base of the second NPN transistor Q2; for the fourth NPN transistor Q4, the emitter is connected to the base of the second NPN transistor Q2, and the base and the collector are short-circuited and connected to the first power supply VCC1 through the seventh resistor R7.

[0006] In one embodiment, the second bias voltage driving buffer circuit also includes a fifth resistor R5 and a tenth resistor R10, the collector of the first NPN transistor Q1 is connected to the second power supply VCC2 through the tenth resistor R10, and the emitter is connected to the bias circuit output terminal through the fifth resistor R5, and the bias circuit output terminal is used to connect to the base of the transistor in the RF power amplifier PA.

[0007] In one embodiment, the second filtering circuit is a filtering circuit on the base of the first NPN transistor Q1.

[0008] In one embodiment, the second filtering circuit includes a first non-polar capacitor C1 , one end of the first non-polar capacitor C1 is connected to the base of the first NPN transistor Q1 , and the other end is grounded.

[0009] In a second aspect, an embodiment provides a radio frequency bias circuit for improving temperature stability, comprising a second bias voltage driving buffer circuit, a second voltage regulating circuit and a second filtering circuit; the second bias voltage driving buffer circuit comprises a first NPN transistor Q1, the second filtering circuit is used to filter out the radio frequency signal entering the first NPN transistor Q1, and the second voltage regulating circuit is used to adjust the voltage on the base of the first NPN transistor Q1; The second voltage regulating circuit includes a second NPN transistor Q2, a third NPN transistor Q3, a fourth NPN transistor Q4, a second resistor R2, a third resistor R3, a fourth resistor R4, a sixth resistor R6 and a seventh resistor R7; wherein, for the second NPN transistor Q2, the collector is connected to the collector of the first NPN transistor Q1, the emitter is connected to the base of the third NPN transistor Q3 through the fourth resistor R4, and the base is connected to the first power supply VCC1 through the sixth resistor R6; for the third NPN transistor Q3, the base is grounded through the third resistor R3, the emitter is grounded through the second resistor R2, and the collector is connected to the base of the second NPN transistor Q2; for the fourth NPN transistor Q4, the emitter is connected to the base of the second NPN transistor Q2, and the base and the collector are short-circuited and connected to the first power supply VCC1 through the seventh resistor R7.

[0010] In one embodiment, the second bias voltage driving buffer circuit further includes a fifth resistor R5 and a tenth resistor R10, the collector of the first NPN transistor Q1 is connected to the second power supply VCC2 through the tenth resistor R10, and the emitter is connected to the bias circuit output terminal through the fifth resistor R5.

[0011] In one embodiment, the bias circuit output terminal is used to connect to the base of a transistor in a radio frequency power amplifier PA.

[0012] In one embodiment, the second filtering circuit is a filtering circuit on the base of the first NPN transistor Q1.

[0013] In one embodiment, the second filtering circuit includes a first non-polar capacitor C1 , one end of the first non-polar capacitor C1 is connected to the base of the first NPN transistor Q1 , and the other end is grounded.

[0014] The beneficial effects of the present invention are: When the temperature rises, the fourth NPN transistor Q4 with the base and collector short-circuited is equivalent to a diode, and the voltage drop on the equivalent diode will decrease as the temperature rises, so that the base voltage of the first NPN transistor Q1 will increase, and the voltage on the output terminal of the bias circuit will also increase accordingly, then the static operating point of the RF power amplifier will also increase, thereby compensating for the gain reduction problem of the RF power amplifier due to the temperature increase. Therefore, the setting of the seventh resistor R7 and the fourth NPN transistor Q4 reduces the impact caused by temperature changes, so that the output power of the RF power amplifier under the condition of fixed input signal power is stable within a smaller range with the change of ambient temperature. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of the structure of a radio frequency bias circuit in a traditional solution; Figure 2 It is a structural schematic diagram of a radio frequency bias circuit for improving temperature stability according to an embodiment of the present application; Figure 3 It is a schematic diagram of a radio frequency power amplifier circuit for improving temperature stability according to an embodiment of the present application; Figure 4 It is a schematic diagram of the gain change of the RF power amplifier caused by a conventional RF bias circuit and a RF bias circuit for improving temperature stability in an embodiment of the present application under the same ambient temperature change range.

[0016] In the figure: 01, a first bias voltage driving buffer circuit, 02, a first voltage regulating circuit, 03, a first filtering circuit, 04, a second bias voltage driving buffer circuit, 05, a second voltage regulating circuit, 06, a second filtering circuit. DETAILED DESCRIPTION

[0017] The present invention is further described in detail below by specific embodiments in conjunction with the accompanying drawings. Wherein similar elements in different embodiments adopt associated similar element numbers. In the following embodiments, many detailed descriptions are for making the present application better understood. However, those skilled in the art can easily recognize that some features can be omitted in different situations, or can be replaced by other elements, materials, methods. In some cases, some operations related to the present application are not shown or described in the specification, this is to avoid the core part of the present application being overwhelmed by too much description, and for those skilled in the art, it is not necessary to describe these related operations in detail, and they can fully understand the related operations according to the description in the specification and the general technical knowledge in the art.

[0018] In addition, the features, operations or characteristics described in the specification can be combined in any appropriate manner to form various implementations. At the same time, the steps or actions in the method description can also be interchanged or adjusted in a manner that is obvious to those skilled in the art. Therefore, the various sequences in the specification and the drawings are only for the purpose of clearly describing a certain embodiment and are not meant to be a required sequence, unless otherwise specified that a certain sequence must be followed.

[0019] The serial numbers assigned to the components herein, such as "first", "second", etc., are only used to distinguish the objects described and do not have any order or technical meaning. The "connection" and "coupling" mentioned in this application, unless otherwise specified, include direct and indirect connections (couplings).

[0020] To facilitate the description of the inventive concept of the present application, a brief description of the radio frequency power amplifier is given below.

[0021] The matching circuit of the RF power amplifier may include an RF bias circuit. For a current RF bias circuit, please refer to Figure 1 , including a first bias voltage driving buffer circuit 01, a first voltage regulating circuit 02 and a first filtering circuit 03. Among them, the first bias voltage driving buffer circuit 01 includes a fifth NPN transistor Q5; the first filtering circuit 03 is used to filter out the radio frequency signal entering the fifth NPN transistor Q5; the first voltage regulating circuit 02 is used to adjust the voltage on the base of the fifth NPN transistor Q5.

[0022] The first voltage regulating circuit 02 includes a sixth NPN transistor Q6, a seventh NPN transistor Q7, an eighth resistor R8, a ninth resistor R9, an eleventh resistor R11 and a twelfth resistor R12. For the sixth NPN transistor Q6, the collector is connected to the collector of the fifth NPN transistor Q5, the emitter is connected to the base of the seventh NPN transistor Q7 through the eleventh resistor R11, and the base is connected to the first power supply VCC1 through the twelfth resistor R12; for the seventh NPN transistor Q7, the base is grounded through the ninth resistor R9, the emitter is grounded through the eighth resistor R8, and the collector is connected to the base of the sixth NPN transistor Q6.

[0023] However, the applicant discovered during research that the gain of the RF power amplifier will decrease with the increase of the ambient temperature (usually -40℃~+85℃). In a system without AGC (automatic gain control) function, the output power of the RF power amplifier will change with the change of gain, and the change is quite significant. In extreme cases, the RF power amplifier will be over-pushed and fail.

[0024] In view of this, an embodiment of the present application provides an RF power amplifier circuit and an RF bias circuit for improving temperature stability, which can reduce the impact caused by temperature changes and make the output power of the RF power amplifier under fixed input signal power conditions stable within a smaller range as the ambient temperature changes.

[0025] For ease of understanding, a radio frequency bias circuit for improving temperature stability provided in an embodiment of the present application is first described below.

[0026] Please refer to Figure 2, an RF bias circuit for improving temperature stability provided in an embodiment of the application, the RF bias circuit includes a second bias voltage driving buffer circuit 04, a second voltage regulating circuit 05 and a second filtering circuit 06. Among them, the second bias voltage driving buffer circuit 04 includes a first NPN transistor Q1; the second filtering circuit 06 is used to filter out the RF signal entering the first NPN transistor Q1; the second voltage regulating circuit 05 is used to adjust the voltage on the base of the first NPN transistor Q1, thereby controlling the voltage at the emitter node C of the first NPN transistor Q1.

[0027] The second voltage regulating circuit 05 includes a second NPN transistor Q2, a third NPN transistor Q3, a fourth NPN transistor Q4, a second resistor R2, a third resistor R3, a fourth resistor R4, a sixth resistor R6 and a seventh resistor R7. For the second NPN transistor Q2, the collector is connected to the collector of the first NPN transistor Q1, the emitter is connected to the base of the third NPN transistor Q3 through the fourth resistor R4, and the base is connected to the first power supply VCC1 through the sixth resistor R6; for the third NPN transistor Q3, the base is grounded through the third resistor R3, the emitter is grounded through the second resistor R2, and the collector is connected to the base of the second NPN transistor Q2; for the fourth NPN transistor Q4, the emitter is connected to the base of the second NPN transistor Q2, and the base and the collector are short-circuited and connected to the first power supply VCC1 through the seventh resistor R7.

[0028] To Figure 2 The RF bias circuit is applied to the RF power amplifier. For example, the bias circuit of the RF power amplifier provides a bias voltage for the base of the RF power amplifier. When the temperature changes, the gain of the RF power amplifier will also change with the temperature. Usually, the gain of the RF power amplifier will decrease as the temperature rises. Please refer to Figure 2 In the embodiment of the present application, the gain of the RF power amplifier is stabilized within a smaller range by adding a seventh resistor R7 and a fourth NPN transistor Q4 with a base and a collector short-circuited.

[0029] Please refer to Figure 2, when the temperature rises, the fourth NPN transistor Q4 with the base and collector short-circuited is equivalent to a diode, and the voltage drop on the equivalent diode will decrease as the temperature rises. Due to the decrease in the voltage drop on the equivalent diode, this leads to a decrease in the voltage drop across the series circuit formed by the seventh resistor R7 and the fourth NPN transistor Q4, thereby increasing the voltage at node B. When the voltage at node B increases, since the voltage at node B is the same as the base voltage of the first NPN transistor Q1, the base voltage of the first NPN transistor Q1 will also increase. When the base voltage of the first NPN transistor Q1 increases, due to the emitter voltage following characteristics of the first NPN transistor Q1, the voltage at the emitter of the first NPN transistor Q1, that is, node C, will also increase. When the voltage at node C increases, the voltage at the output terminal of the bias circuit will also increase accordingly.

[0030] The voltage on the output terminal of the bias circuit is the bias voltage given to the RF power amplifier by the entire RF bias circuit. When the bias voltage increases, the static operating point of the RF power amplifier will also increase. When the static operating point of the RF power amplifier increases, the gain of the RF power amplifier will also increase. Because when the temperature rises, the gain of the RF power amplifier will decrease when the static operating point remains unchanged, but the equivalent diode will increase the static operating point of the RF power amplifier when the temperature rises to achieve the increase in the gain of the RF power amplifier, thereby compensating for the problem of the decrease in the gain of the RF power amplifier due to the increase in temperature. Therefore, the setting of the seventh resistor R7 and the fourth NPN transistor Q4 reduces the impact caused by temperature changes, so that the output power of the RF power amplifier under the condition of fixed input signal power is stable within a smaller range with the change of ambient temperature.

[0031] Those skilled in the art can understand that the effect of reducing the influence caused by temperature change can be achieved by adjusting the resistance value of the seventh resistor R7. The smaller the seventh resistor R7 is, the higher the static operating point of the RF power amplifier circuit will be when the temperature rise is the same. Because when the seventh resistor R7 is smaller, when the current flowing through the seventh resistor R7 remains unchanged, the voltage drop across the seventh resistor R7 will also be smaller, so the voltage on the output terminal of the bias circuit will be higher.

[0032] In one embodiment, the second bias voltage driving buffer circuit 04 further includes a fifth resistor R5 and a tenth resistor R10. The collector of the first NPN transistor Q1 is connected to the second power supply VCC2 through the tenth resistor R10, and the emitter is connected to the bias circuit output terminal through the fifth resistor R5.

[0033] In one embodiment, the bias circuit output terminal is used to connect to the base of a transistor in a radio frequency power amplifier.

[0034] In one embodiment, the second filter circuit 06 is a filter circuit on the base of the first NPN transistor Q1, which is used to filter out the radio frequency signal entering the second bias voltage driving buffer circuit 04 to prevent the radio frequency signal from interfering with the second bias voltage driving buffer circuit 04.

[0035] In one embodiment, the second filtering circuit 06 includes a first non-polar capacitor C1, wherein one end of the first non-polar capacitor C1 is connected to the base of the first NPN transistor Q1, and the other end is grounded.

[0036] In one embodiment of the present application, a radio frequency power amplifier circuit for improving temperature stability is provided. Figure 3 , including a radio frequency power amplifier PA and its matching circuit, wherein the matching circuit includes an input matching circuit IMN, an output matching circuit OMN and a radio frequency bias circuit. The input end of the radio frequency power amplifier PA is respectively connected to the radio frequency signal input end IN through the input matching circuit IMN, and is connected to the base power supply of the transistor in the radio frequency power amplifier PA through the radio frequency bias circuit; the output end of the radio frequency power amplifier PA is connected to the radio frequency signal output end OUT through the output matching circuit OMN. Among them, the radio frequency bias circuit can adopt the radio frequency bias circuit of any embodiment of the radio frequency bias circuit for improving temperature stability provided by the present application. In this way, the influence of temperature changes on the gain of the radio frequency power amplifier can be reduced, so that the output power of the radio frequency power amplifier under the condition of fixed input signal power is stable within a smaller range with the change of ambient temperature.

[0037] Please refer to Figure 4 , Figure 4 When the ambient temperature changes from -40°C to +85°C, the gain change of the RF power amplifier under the RF bias circuit of the traditional solution is 3dB, and the gain change of the RF power amplifier under the RF bias circuit of the present application solution is 0.5dB. It can be seen that when the ambient temperature changes, the gain of the RF power amplifier under the RF bias circuit of the present application solution is stable within a smaller range, which significantly reduces the impact of temperature changes on the gain of the RF power amplifier.

[0038] The above specific examples are used to illustrate the present invention, which is only used to help understand the present invention and is not intended to limit the present invention. For those skilled in the art, according to the concept of the present invention, some simple deductions, modifications or substitutions can be made.

Claims

1. A radio frequency power amplifier circuit for improving temperature stability, characterized in that: It includes a radio frequency power amplifier PA and a matching circuit thereof, wherein the matching circuit includes an input matching circuit IMN, an output matching circuit OMN and a radio frequency bias circuit; wherein the input end of the radio frequency power amplifier PA is connected to a radio frequency signal input end IN through the input matching circuit IMN, and is connected to a base power supply of a transistor in the radio frequency power amplifier PA through the radio frequency bias circuit; the output end of the radio frequency power amplifier PA is connected to a radio frequency signal output end OUT through the output matching circuit OMN; The RF bias circuit includes a second bias voltage driving buffer circuit, a second voltage regulating circuit and a second filtering circuit; the second bias voltage driving buffer circuit includes a first NPN transistor Q1, the second filtering circuit is used to filter out the RF signal entering the first NPN transistor Q1, and the second voltage regulating circuit is used to regulate the voltage on the base of the first NPN transistor Q1; The second voltage regulating circuit includes a second NPN transistor Q2, a third NPN transistor Q3, a fourth NPN transistor Q4, a second resistor R2, a third resistor R3, a fourth resistor R4, a sixth resistor R6 and a seventh resistor R7; wherein, for the second NPN transistor Q2, the collector is connected to the collector of the first NPN transistor Q1, the emitter is connected to the base of the third NPN transistor Q3 through the fourth resistor R4, and the base is connected to the first power supply VCC1 through the sixth resistor R6; for the third NPN transistor Q3, the base is grounded through the third resistor R3, the emitter is grounded through the second resistor R2, and the collector is connected to the base of the second NPN transistor Q2; for the fourth NPN transistor Q4, the emitter is connected to the base of the second NPN transistor Q2, and the base and the collector are short-circuited and connected to the first power supply VCC1 through the seventh resistor R7.

2. The radio frequency power amplifier circuit according to claim 1, characterized in that: The second bias voltage driving buffer circuit also includes a fifth resistor R5 and a tenth resistor R10. The collector of the first NPN transistor Q1 is connected to the second power supply VCC2 through the tenth resistor R10, and the emitter is connected to the bias circuit output terminal through the fifth resistor R5. The bias circuit output terminal is used to connect to the base of the transistor in the RF power amplifier PA.

3. The radio frequency power amplifier circuit according to claim 1, characterized in that: The second filtering circuit is a filtering circuit on the base of the first NPN transistor Q1.

4. The radio frequency power amplifier circuit according to claim 3, characterized in that: The second filtering circuit includes a first non-polar capacitor C1 , one end of which is connected to the base of the first NPN transistor Q1 , and the other end of which is grounded.

5. A radio frequency bias circuit for improving temperature stability, characterized in that: It includes a second bias voltage driving buffer circuit, a second voltage regulating circuit and a second filtering circuit; the second bias voltage driving buffer circuit includes a first NPN transistor Q1, the second filtering circuit is used to filter out the radio frequency signal entering the first NPN transistor Q1, and the second voltage regulating circuit is used to adjust the voltage on the base of the first NPN transistor Q1; The second voltage regulating circuit includes a second NPN transistor Q2, a third NPN transistor Q3, a fourth NPN transistor Q4, a second resistor R2, a third resistor R3, a fourth resistor R4, a sixth resistor R6 and a seventh resistor R7; wherein, for the second NPN transistor Q2, the collector is connected to the collector of the first NPN transistor Q1, the emitter is connected to the base of the third NPN transistor Q3 through the fourth resistor R4, and the base is connected to the first power supply VCC1 through the sixth resistor R6; for the third NPN transistor Q3, the base is grounded through the third resistor R3, the emitter is grounded through the second resistor R2, and the collector is connected to the base of the second NPN transistor Q2; for the fourth NPN transistor Q4, the emitter is connected to the base of the second NPN transistor Q2, and the base and the collector are short-circuited and connected to the first power supply VCC1 through the seventh resistor R7.

6. The radio frequency bias circuit according to claim 5, characterized in that: The second bias voltage driving buffer circuit further includes a fifth resistor R5 and a tenth resistor R10. The collector of the first NPN transistor Q1 is connected to the second power supply VCC2 through the tenth resistor R10, and the emitter is connected to the bias circuit output terminal through the fifth resistor R5.

7. The radio frequency bias circuit according to claim 6, characterized in that: The bias circuit output terminal is used to connect to the base of the transistor in the radio frequency power amplifier PA.

8. The radio frequency power amplifier circuit according to claim 5, characterized in that: The second filtering circuit is a filtering circuit on the base of the first NPN transistor Q1.

9. The radio frequency power amplifier circuit according to claim 8, characterized in that: The second filtering circuit includes a first non-polar capacitor C1 , one end of which is connected to the base of the first NPN transistor Q1 , and the other end of which is grounded.

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