Radio frequency power amplifier and radio frequency chip

Abstract

The invention is applicable to the technical field of communication, and particularly relates to a radio frequency power amplifier and a radio frequency chip, the radio frequency power amplifier comprises an input matching circuit, a power amplifier, a power detection circuit and a self-adaptive bias control circuit; the input end of the power detection circuit is connected with the input end of the power amplifier, and the output end of the power detection circuit is connected with the input end of the adaptive bias control circuit; the power detection circuit is used for detecting the input power of the power amplifier and sending an adjusting signal to the adaptive bias control circuit; the output end of the self-adaptive bias control circuit is connected with the input end of the power amplifier; and the adaptive bias control circuit is used for adjusting the bias current of the power amplifier according to the adjusting signal. Compared with the prior art, the average efficiency and the linearity index of the power amplifier can be improved at the same time, the overall circuit structure is simple, and an additional control circuit does not need to be added.

Description

Technical Field

[0001] The present invention is applicable to the field of communication technology, and in particular relates to a radio frequency power amplifier and a radio frequency chip. Background Art

[0002] With the rapid development of communication technology, in order to adapt to higher transmission rates and spectrum efficiency, a series of increasingly complex modulation technologies have emerged. These complex modulation signals are often non-constant envelopes, so they usually have a large peak-to-average ratio. For a fixed bias power amplifier, its efficiency peaks when it is close to saturation, while the linearity deteriorates when the power amplifier is close to saturation. Therefore, how to improve the linearity of the power amplifier and how to improve the efficiency of the power amplifier at the average power point (backoff zone) have become two major research hotspots.

[0003] The simplest bipolar transistor bias circuit is realized by two resistors in series to divide the voltage. Figure 1 As shown, Figure 1 It is a structural diagram of the bias circuit of the related technology. When the input power increases, due to the clamping characteristics of the diode, the excessive forward voltage and negative current applied to the base-emitter diode of the output stage power tube are limited. Therefore, the DC voltage across the base-emitter decreases and the DC current increases, which leads to a decrease in transconductance, a decrease in gain and phase distortion, resulting in a deterioration in linearity. Figure 1 The bias circuit realized by connecting two resistors in series to divide the voltage will bring serious amplitude and phase distortion problems, thus affecting the linearity index of the entire power amplifier.

[0004] In order to improve the efficiency of the power amplifier in the entire power range, envelope tracking technology is often used. It dynamically adjusts the drain / collector voltage of the power amplifier according to the input RF power, so that the power amplifier always works in a saturated state in the entire power range, thereby effectively improving the back-off zone efficiency and average efficiency of the power amplifier. However, envelope tracking often requires additional devices such as DCDC converters to control the bias voltage, which will increase the size of the module and bring higher costs. In addition, because the power amplifier is always in a saturated working state under dynamic voltage modulation, the linearity of the envelope tracking amplifier is worse than that of a constant voltage power amplifier.

[0005] Therefore, there is an urgent need for a new RF power amplifier and RF chip to solve the above technical problems. Summary of the invention

[0006] The present invention provides a radio frequency power amplifier and a radio frequency chip, aiming to simultaneously improve the linearity and average efficiency of the radio frequency power amplifier.

[0007] In a first aspect, the present invention provides a radio frequency power amplifier, the radio frequency power amplifier comprising an input matching circuit, a power amplifier, a power detection circuit and an adaptive bias control circuit; The input end of the input matching circuit serves as the input end of the RF power amplifier and is used to receive an input signal. The output end of the input matching circuit is connected to the input end of the power amplifier. The input matching circuit is used to achieve input impedance matching. The output end of the power amplifier is used as the output end of the radio frequency power amplifier to output a radio frequency signal; The input end of the power detection circuit is connected to the input end of the power amplifier, and the output end of the power detection circuit is connected to the input end of the adaptive bias control circuit; the power detection circuit is used to detect the input power of the power amplifier and send an adjustment signal to the adaptive bias control circuit; The output end of the adaptive bias control circuit is connected to the input end of the power amplifier; the adaptive bias control circuit is used to adjust the bias current of the power amplifier according to the adjustment signal.

[0008] Preferably, the power detection circuit comprises a first resistor, a transistor and a first capacitor; The first end of the first resistor serves as the input end of the power detection circuit, the second end of the first resistor is connected to the input end of the transistor, the ground end of the transistor is grounded, the output end of the transistor serves as the output end of the power detection circuit, the first end of the first capacitor is connected to the output end of the transistor, and the second end of the first capacitor is grounded; the first capacitor is a bypass capacitor, and the first resistor is an adjustable resistor.

[0009] Preferably, the transistor is a first triode; the base of the first triode serves as the input end of the transistor, the collector of the first triode serves as the output end of the transistor, and the emitter of the first triode serves as the ground end of the transistor; Preferably, the transistor is a field effect transistor; the gate of the field effect transistor serves as the input terminal of the transistor, the drain of the field effect transistor serves as the output terminal of the transistor, and the source of the field effect transistor serves as the ground terminal of the transistor.

[0010] Preferably, the adaptive bias control circuit comprises a second resistor, a third resistor, a fourth resistor, a second triode, a third triode and a second capacitor; The first end of the second resistor serves as the input end of the adaptive bias control circuit, the second end of the second resistor is connected to the base of the second transistor, the emitter of the second transistor is grounded, the collector of the second transistor is respectively connected to the first end of the fourth resistor, the first end of the second capacitor and the base of the third transistor, the emitter of the third transistor serves as the output end of the adaptive bias control circuit, the second end of the second capacitor is grounded, the first end of the third resistor, the second end of the fourth resistor and the collector of the third transistor are respectively connected to the external power supply voltage, and the second end of the third resistor is connected to the first end of the second resistor.

[0011] Preferably, the input matching circuit comprises a third capacitor, a first end of the third capacitor serves as an input end of the input matching circuit, and a second end of the third capacitor serves as an output end of the input matching circuit.

[0012] Preferably, the power amplifier is a fourth transistor, the base of the fourth transistor serves as the input end of the power amplifier, the emitter of the fourth transistor is grounded, and the collector of the fourth transistor serves as the output end of the power amplifier.

[0013] In a second aspect, the present invention further provides a radio frequency chip, wherein the radio frequency chip comprises a radio frequency power amplifier as described in any one of the above embodiments.

[0014] Compared with the prior art, the present invention uses an input matching circuit, a power amplifier, a power detection circuit and an adaptive bias control circuit; the input end of the input matching circuit is used as the input end of the radio frequency power amplifier for receiving an input signal, and the output end of the input matching circuit is connected to the input end of the power amplifier; the output end of the power amplifier is used as the output end of the radio frequency power amplifier for outputting a radio frequency signal; the input end of the power detection circuit is connected to the input end of the power amplifier, and the output end of the power detection circuit is connected to the input end of the adaptive bias control circuit; the power detection circuit is used to detect the input power of the power amplifier and send an adjustment signal to the adaptive bias control circuit; the output end of the adaptive bias control circuit is connected to the input end of the power amplifier; and the adaptive bias control circuit is used to adjust the bias current of the power amplifier according to the adjustment signal. In this way, the present invention can simultaneously improve the average efficiency and linearity index of the power amplifier, and its overall circuit structure is simple, without adding an additional control circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The present invention will be described in detail below in conjunction with the accompanying drawings. The above and other aspects of the present invention will become clearer and easier to understand through the detailed description made in conjunction with the following drawings. In the accompanying drawings: Figure 1 is a schematic diagram of a bias circuit of the related art; Figure 2 It is a structural schematic diagram of a radio frequency power amplifier provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0016] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0017] Embodiment 1 Please refer to Figure 2 , Figure 2 is a schematic diagram of the structure of a radio frequency power amplifier provided in an embodiment of the present invention. The present invention provides a radio frequency power amplifier 100, the radio frequency power amplifier 100 comprising an input matching circuit 1, a power amplifier 2, a power detection circuit 3 and an adaptive bias control circuit 4; The input end of the input matching circuit 1 is used as the input end of the RF power amplifier 100 to receive an input signal, and the output end of the input matching circuit 1 is connected to the input end of the power amplifier 2; the input matching circuit 1 is used to achieve input impedance matching; The output end of the power amplifier 2 serves as the output end of the RF power amplifier 100, and is used to output a RF signal; The input end of the power detection circuit 3 is connected to the input end of the power amplifier 2, and the output end of the power detection circuit 3 is connected to the input end of the adaptive bias control circuit 4; the power detection circuit 3 is used to detect the input power of the power amplifier 2 and send an adjustment signal to the adaptive bias control circuit 4; The output end of the adaptive bias control circuit 4 is connected to the input end of the power amplifier 2; the adaptive bias control circuit 4 is used to adjust the bias current of the power amplifier 2 according to the adjustment signal.

[0018] In the embodiment of the present invention, the power detection circuit 3 includes a first resistor R1, a transistor 31 and a first capacitor C1; The first end of the first resistor R1 serves as the input end of the power detection circuit 3, the second end of the first resistor R1 is connected to the input end of the transistor 31, the ground end of the transistor 31 is grounded, the output end of the transistor 31 serves as the output end of the power detection circuit 3, the first end of the first capacitor C1 is connected to the output end of the transistor 31, and the second end of the first capacitor C1 is grounded; the first capacitor C1 is a bypass capacitor, and the first resistor R1 is an adjustable resistor.

[0019] In the embodiment of the present invention, the transistor 31 is a first triode HBT1 or a field effect transistor.

[0020] The base of the first transistor HBT1 serves as the input terminal of the transistor 31, the collector of the first transistor HBT1 serves as the output terminal of the transistor 31, and the emitter of the first transistor HBT1 serves as the ground terminal of the transistor 31. Specifically, the present invention takes the transistor 31 as the first transistor HBT1 as an example.

[0021] The gate of the field effect tube serves as the input terminal of the transistor 31 , the drain of the field effect tube serves as the output terminal of the transistor 31 , and the source of the field effect tube serves as the ground terminal of the transistor 31 .

[0022] In the embodiment of the present invention, the adaptive bias control circuit 4 includes a second resistor R2, a third resistor R3, a fourth resistor R4, a second transistor HBT2, a third transistor HBT3 and a second capacitor C2; The first end of the second resistor R2 serves as the input end of the adaptive bias control circuit 4, the second end of the second resistor R2 is connected to the base of the second transistor HBT2, the emitter of the second transistor HBT2 is grounded, the collector of the second transistor HBT2 is respectively connected to the first end of the fourth resistor R4, the first end of the second capacitor C2 and the base of the third transistor HBT3, the emitter of the third transistor HBT3 serves as the output end of the adaptive bias control circuit 4, the second end of the second capacitor C2 is grounded, the first end of the third resistor R3, the second end of the fourth resistor R4 and the collector of the third transistor HBT3 are respectively connected to the external power supply voltage, and the second end of the third resistor R3 is connected to the first end of the second resistor R2.

[0023] In the embodiment of the present invention, the input matching circuit 1 includes a third capacitor C3, a first end of the third capacitor C3 serves as an input end of the input matching circuit 1, and a second end of the third capacitor C3 serves as an output end of the input matching circuit 1.

[0024] In an embodiment of the present invention, the power amplifier 2 is a fourth transistor HBT4, the base of the fourth transistor HBT4 serves as the input end of the power amplifier 2, the emitter of the fourth transistor HBT4 is grounded, and the collector of the fourth transistor HBT4 serves as the output end of the power amplifier 2.

[0025] Specifically, in the specific implementation process, it is first necessary to adjust the resistance value of the first resistor R1 and the emitter area of ​​the first transistor HBT1 (in the design stage, the resistance value of the first resistor R1 and the emitter area of ​​the first transistor HBT1 are determined according to the actual situation) to determine the power input to the first transistor HBT1. When the RF signal enters the power amplifier 2, a part of the energy will be transmitted to the base of the first transistor HBT1 through the first resistor R1. The size of this part of the power is jointly determined by the resistance value of the first resistor R1 and the emitter area of ​​the transistor 31.

[0026] As the input power increases, the collector current of the first transistor HBT1 also increases. Due to the presence of the first capacitor C1, the RF power amplified by the first transistor HBT1 will be short-circuited to the ground by it, and will not continue to be transmitted to the second transistor HBT2. The increased collector current of the first transistor HBT1 will cause the base voltage of the second transistor HBT2 to decrease due to the action of the third resistor R3, so that the collector current of the second transistor HBT2 will also decrease. Due to the presence of the fourth resistor R4, the base voltage of the third transistor HBT3 will increase as the collector current of the second transistor HBT2 decreases. Therefore, the emitter current of the third transistor HBT3 will increase, and the collector current of the fourth transistor HBT4 (i.e., the power amplifier 2) will also increase. Therefore, the bias current of the adaptive bias control circuit 4 is low at low input power, and when the input power increases, its bias current also increases, so the power amplifier 2 can be controlled to be in a state close to saturation in the entire power range, thereby improving its average efficiency.

[0027] In addition, in the circuit of the RF power amplifier 100 of the present invention, all RF power at the node P is bypassed to the ground by the second capacitor C2, so the DC voltage at point P remains constant. When the input power increases, the DC current generated after rectification by the third transistor HBT3 increases, and the DC current flowing into the fourth transistor HBT4 increases. At the same time, the base-emitter junction voltage of the third transistor HBT3 decreases, thereby compensating for the DC voltage across the base-emitter of the fourth transistor HBT4. Under the joint action of the second capacitor C2 and the third transistor HBT3, the linearity of the power amplifier 2 can also be effectively optimized.

[0028] Compared with the prior art, the present invention uses an input matching circuit, a power amplifier, a power detection circuit and an adaptive bias control circuit; the input end of the input matching circuit is used as the input end of the radio frequency power amplifier for receiving an input signal, and the output end of the input matching circuit is connected to the input end of the power amplifier; the output end of the power amplifier is used as the output end of the radio frequency power amplifier for outputting a radio frequency signal; the input end of the power detection circuit is connected to the input end of the power amplifier, and the output end of the power detection circuit is connected to the input end of the adaptive bias control circuit; the power detection circuit is used to detect the input power of the power amplifier and send an adjustment signal to the adaptive bias control circuit; the output end of the adaptive bias control circuit is connected to the input end of the power amplifier; and the adaptive bias control circuit is used to adjust the bias current of the power amplifier according to the adjustment signal. In this way, the present invention can simultaneously improve the average efficiency and linearity index of the power amplifier, and its overall circuit structure is simple, without adding an additional control circuit.

[0029] Embodiment 2 An embodiment of the present invention further provides a radio frequency chip, which includes the radio frequency power amplifier 100 as described in the above embodiment and can achieve the same technical effect. Please refer to the description in the above embodiment and will not be repeated here.

[0030] 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.

[0031] The embodiments of the present invention are described above in conjunction with the accompanying drawings. What is disclosed is only the preferred embodiment of the present invention. However, the present invention is not limited to the above-mentioned specific implementation manner. The above-mentioned specific implementation manner is only illustrative rather than restrictive. Under the enlightenment of the present invention, ordinary technicians in this field can also make many forms and equivalent changes without departing from the scope of protection of the purpose of the present invention and the claims, all of which are within the protection of the present invention.

Claims

1. A radio frequency power amplifier, characterized in that: The radio frequency power amplifier comprises an input matching circuit, a power amplifier, a power detection circuit and an adaptive bias control circuit; The input end of the input matching circuit serves as the input end of the RF power amplifier and is used to receive an input signal. The output end of the input matching circuit is connected to the input end of the power amplifier. The input matching circuit is used to achieve input impedance matching. The output end of the power amplifier is used as the output end of the radio frequency power amplifier to output a radio frequency signal; The input end of the power detection circuit is connected to the input end of the power amplifier, and the output end of the power detection circuit is connected to the input end of the adaptive bias control circuit; the power detection circuit is used to detect the input power of the power amplifier and send an adjustment signal to the adaptive bias control circuit; The output end of the adaptive bias control circuit is connected to the input end of the power amplifier; the adaptive bias control circuit is used to adjust the bias current of the power amplifier according to the adjustment signal.

2. The radio frequency power amplifier according to claim 1, characterized in that: The power detection circuit includes a first resistor, a transistor and a first capacitor; The first end of the first resistor serves as the input end of the power detection circuit, the second end of the first resistor is connected to the input end of the transistor, the ground end of the transistor is grounded, the output end of the transistor serves as the output end of the power detection circuit, the first end of the first capacitor is connected to the output end of the transistor, and the second end of the first capacitor is grounded; the first capacitor is a bypass capacitor, and the first resistor is an adjustable resistor.

3. The radio frequency power amplifier according to claim 2, characterized in that: The transistor is a first triode; The base of the first transistor serves as the input terminal of the transistor, the collector of the first transistor serves as the output terminal of the transistor, and the emitter of the first transistor serves as the ground terminal of the transistor.

4. The radio frequency power amplifier according to claim 2, characterized in that: The transistor is a field effect transistor; the gate of the field effect transistor serves as the input end of the transistor, the drain of the field effect transistor serves as the output end of the transistor, and the source of the field effect transistor serves as the ground end of the transistor.

5. The radio frequency power amplifier according to claim 1, characterized in that: The adaptive bias control circuit includes a second resistor, a third resistor, a fourth resistor, a second triode, a third triode and a second capacitor; The first end of the second resistor serves as the input end of the adaptive bias control circuit, the second end of the second resistor is connected to the base of the second transistor, the emitter of the second transistor is grounded, the collector of the second transistor is respectively connected to the first end of the fourth resistor, the first end of the second capacitor and the base of the third transistor, the emitter of the third transistor serves as the output end of the adaptive bias control circuit, the second end of the second capacitor is grounded, the first end of the third resistor, the second end of the fourth resistor and the collector of the third transistor are respectively connected to the external power supply voltage, and the second end of the third resistor is connected to the first end of the second resistor.

6. The radio frequency power amplifier according to claim 1, characterized in that: The input matching circuit includes a third capacitor, a first end of the third capacitor serves as an input end of the input matching circuit, and a second end of the third capacitor serves as an output end of the input matching circuit.

7. The radio frequency power amplifier according to claim 1, characterized in that: The power amplifier is a fourth transistor, the base of the fourth transistor serves as the input end of the power amplifier, the emitter of the fourth transistor is grounded, and the collector of the fourth transistor serves as the output end of the power amplifier.

8. A radio frequency chip, characterized in that: The radio frequency chip includes a radio frequency power amplifier as described in any one of claims 1 to 7 above.

Images