CN-115483894-B - Power amplifier

Abstract

A power amplifier includes a transistor, a temperature sensor, and a filter. The transistor is used for receiving the bias signal and amplifying the radio frequency signal. The temperature sensor is arranged near the transistor and is used for detecting the temperature of the transistor to correspondingly provide a voltage signal at the control node. The filter is coupled to the temperature sensor for filtering the voltage signal to generate a filtered voltage. The bias signal is adjusted according to the filtered voltage.

Inventors

• PENG TIANYUN
• CHEN ZHISHENG

Assignees

• 立积电子股份有限公司

Dates

Publication Date

20260512

Application Date

20210730

Priority Date

20210623

Claims (19)

1. 1. A power amplifier which comprises a power amplifier circuit and a power amplifier circuit, characterized by comprising: a first transistor configured to receive a bias signal and amplify a radio frequency signal; A temperature sensor disposed near the first transistor for detecting a temperature of the first transistor to correspondingly provide a first voltage signal at a control node, and The first filter is coupled to the temperature sensor and is used for filtering the first voltage signal to generate a filtering voltage, wherein the first filter comprises a variable impedance component, the variable impedance component is used for adjusting an impedance according to a control signal so as to provide a first impedance in a first interval and a second impedance in a second interval after the first interval, and the second impedance is larger than the first impedance; wherein the bias signal is adjusted according to the filtered voltage.
2. 2. The power amplifier of claim 1, further comprising a bias circuit coupled to the first filter for generating the bias signal according to the filtered voltage.
3. 3. The power amplifier of claim 2, wherein the bias circuit comprises: a second transistor including a first terminal coupled to a first reference terminal, a second terminal, and a control terminal; a third transistor having a first end, a second end, and a control end coupled to the first end of the third transistor, and A fourth transistor including a first terminal coupled to the second terminal of the third transistor, a second terminal coupled to a second reference terminal, and a control terminal coupled to the first terminal of the fourth transistor.
4. 4. The power amplifier of claim 3, wherein the bias circuit further comprises a first resistor comprising a first terminal coupled to the second terminal of the second transistor and a second terminal.
5. 5. The power amplifier of claim 4, wherein the bias circuit further comprises a ground capacitor comprising a first terminal coupled to the second terminal of the first resistor and a second terminal coupled to the second reference terminal.
6. 6. The power amplifier of claim 3, wherein the bias circuit further comprises a second resistor comprising a first terminal coupled to the control terminal of the second transistor and a second terminal coupled to the first terminal of the third transistor.
7. 7. The power amplifier of claim 1, further comprising a shunt capacitor disposed between the control node and a first reference terminal.
8. 8. The power amplifier of claim 7, wherein the shunt capacitance and the temperature sensor are coupled in parallel.
9. 9. The power amplifier of claim 7, wherein the shunt capacitance is disposed proximate the first transistor.
10. 10. The power amplifier of claim 1, further comprising a bias circuit including the temperature sensor for generating the bias signal based on a variable current.
11. 11. The power amplifier of claim 1, wherein the first filter further comprises: A first capacitor includes a first terminal coupled to the variable impedance element and a second terminal coupled to a second reference terminal.
12. 12. The power amplifier of claim 1 wherein the variable impedance element comprises a first switch coupled in parallel with a resistor.
13. 13. The power amplifier of claim 1 wherein the variable impedance element comprises a first switch coupled in parallel with an inductance.
14. 14. The power amplifier of claim 1, further comprising: a reference node coupled to a current source or a voltage source, and And a second filter coupled between the reference node and the control node for filtering the first voltage signal.
15. 15. The power amplifier of claim 14, wherein the second filter is configured to filter out a noise of the first voltage signal to prevent the noise from affecting the current source or the voltage source.
16. 16. The power amplifier of claim 15, wherein the noise is from an RF signal coupled to the temperature sensor.
17. 17. The power amplifier of claim 1, wherein the first voltage signal comprises a noise from the temperature sensor, the first filter being configured to filter the noise to prevent the noise from affecting the bias signal.
18. 18. A power amplifier which comprises a power amplifier circuit and a power amplifier circuit, characterized by comprising: a first transistor configured to receive a bias signal and amplify a radio frequency signal; A temperature sensor disposed near the first transistor for detecting a temperature of the first transistor to correspondingly provide a first voltage signal at a control node, and The first filter is coupled to the temperature sensor and is used for filtering the first voltage signal to generate a filtering voltage; A buffer coupled to the first filter; a sampling circuit coupled to the buffer for sampling the filtered voltage to generate an updated voltage; a second switch including a first end coupled to the buffer and a second end; a capacitor coupled to the second end of the second switch for storing an initial voltage; A holding circuit coupled to the second end of the second switch; a differential amplifier coupled to the sampling circuit and the holding circuit for generating a differential voltage according to a difference between the initial voltage and the refresh voltage, and A voltage-to-current converter coupled between the differential amplifier and a bias circuit for converting the differential voltage into a differential current; wherein the bias signal is adjusted according to the filtered voltage.
19. 19. The power amplifier of claim 18, wherein the sampling circuit, the capacitor, the differential amplifier, and the bias circuit are fabricated on a first chip and the first transistor is fabricated on a second chip.

Description

Power amplifier Technical Field The present invention relates to power amplifiers, and more particularly to power amplifiers with temperature compensation that maintain a substantially constant gain over temperature. Background Almost all electronic devices use power amplifiers, especially Radio Frequency (RF) devices such as smart phones, wireless network (WiFi) hotspots, and other wireless devices. The power amplifier converts the low power radio frequency signal to a high power radio frequency signal. In operation, the power amplifier is continuously warmed up due to the current flowing therethrough, and the heat generated by the power amplifier reduces the gain, thereby reducing the linearity and signal quality of the power amplifier. The degradation of linearity and signal quality is particularly pronounced during the transmission of long frame data, since heat can accumulate over time. Accordingly, there is a need for a power amplifier that can maintain a substantially constant gain in the event that heat is generated internally and/or externally to the power amplifier. Disclosure of Invention The embodiment of the invention provides a power amplifier, which comprises a transistor, a temperature sensor and a filter. The transistor is used for receiving the bias signal and amplifying the radio frequency signal. The temperature sensor is arranged near the transistor and is used for detecting the temperature of the transistor to correspondingly provide a voltage signal at the control node. The filter is coupled to the temperature sensor for filtering the voltage signal to generate a filtered voltage. The bias signal is adjusted according to the filtered voltage. Drawings Fig. 1 is a block diagram of a power amplifier in an embodiment of the invention. Fig. 2 is a waveform diagram of the voltage signal in fig. 1. Fig. 3 is a waveform diagram of the filtered signal of fig. 1. Fig. 4 is a circuit diagram of the filter of fig. 1. Fig. 5 is a circuit diagram of the bias circuit of fig. 1. Fig. 6 shows waveforms of the power amplifier of fig. 1. Fig. 7 is a block diagram of another power amplifier in an embodiment of the invention. Fig. 8 is a block diagram of another power amplifier in an embodiment of the invention. Fig. 9 is a block diagram of another power amplifier section in an embodiment of the invention. Fig. 10 is a block diagram of another power amplifier in an embodiment of the invention. Symbol description 1,7,8,9,100 Power Amplifier 10 Amplification stage 11,13 Reference terminal 12 Temperature sensor 14,80 Filter 16 Bias circuit 18 Current source 20,30 Envelope 22 Carrier wave 32 Filtering carrier wave 140 Variable impedance component 160 Current source 60 Gain of 70 Adder 90 Second chip 92 First chip 920 Sample and hold circuit 921 Buffer 922 Sampling circuit 924 Hold circuit 925 Differential amplifier 926 Voltage to current converter C, cgnd,923 capacitance Cs shunt capacitance D1 diode GaAs gallium arsenide I current N1 control node Nref reference node R, R1, R2, resistance Sb bias signal Sc control signal SOI silicon-on-insulator Srfi RF input signal Srfo RF output signal SW1, SW2 switch T, t0, t1: time T1 to T4 transistors V+: initial voltage V-: update voltage Vb1 bias voltage Vcc: supply voltage Vf filtered voltage Vss ground or common voltage VTD voltage signal Detailed Description Exemplary embodiments will be described in detail herein with reference to the drawings to facilitate an understanding of the present disclosure. The present disclosure is for illustrative purposes only and is not intended to be limiting. Fig. 1 is a block diagram of a power amplifier 1 according to an embodiment of the present invention. By counteracting the temperature variations caused by self-heating of the power amplifier 1, the power amplifier 1 can maintain a substantially constant gain over time. In addition, the power amplifier 1 may perform preprocessing on a temperature detection signal representing the temperature of the power amplifier 1 to improve the accuracy and speed of temperature compensation, thereby improving the linearity and signal quality of the power amplifier 1. The power amplifier 1 may include an amplification stage 10, a temperature sensor 12, a filter 14, a bias circuit 16, and a current source 18. The amplifying stage 10 may comprise a transistor T1. The temperature sensor 12 may be disposed near the amplifying stage 10, specifically, near the transistor T1. The transistor T1 may be a bipolar junction transistor (bipolar junction transistor, BJT), such as a heterojunction bipolar transistor (heterojunction bipolar transistor, HBT). In some embodiments, the temperature sensor 12 may be in close proximity to the transistor T1. The temperature sensor 12 is coupled to the filter 14, the filter 14 is coupled to the bias circuit 16, and the bias circuit 16 is coupled to the transistor T1. The temperature sensor 12 may include a diode D1. The diode D1 includes a first terminal and a seco