Temperature-compensated power sensing circuit for power amplifiers

• US 20050030101A1
• Filed: 09/10/2004
• Published: 02/10/2005
• Est. Priority Date: 07/19/2002
• Status: Active Grant

• Current Assignee: Micro Mobio Corporation
• Original Assignee: Micro Mobio Corporation
• Inventors: Ichitsuho, Ikuroh, Wang, Weiping
• Granted Patent: US 7,071,783 B2
• Time in Patent Office: Days
• US Class Current: 330/285
• CPC Class Codes: H03G 3/3042 in modulators, frequency-changers, transmitters or power amplifiers transmission power control in bidirectional transmission systems H04W52/04

Abstract

An amplifier circuit for amplifying radio frequency signals having temperature compensation and bias compensation includes a radio frequency power amplifier that receives an input radio frequency signal and outputs an amplified radio frequency signal, and a first transistor performing as a detector diode with its collector and base connected. The base of the first transistor receives the amplified radio frequency signal from the power amplifier, a second DC bias input signal from a regulated DC source, and a third power-sensing signal. The amplifier circuit further includes a second transistor to amplify the DC component of the RF signal from the base of the first transistor. The base of the second transistor is coupled to the base of the first transistor. The collector of the second transistor outputs the power-sensing signal, which is coupled to the regulated DC source through a resistor.

Claims

1. An amplifier circuit for amplifying radio frequency signals having temperature compensation and bias compensation, comprising:

a) a radio frequency power amplifier to receive an input radio frequency signal and to output an amplified radio frequency signal;

b) a detector, including

i) a first base to receive the amplified radio frequency signal, a second DC bias input signal from a regulated DC source, and a third power-sensing signal; and

iii) a first collector connected to the first base; and

c) an amplifier for the DC component of the RF signal from the first base, including

i) a second base coupled to the first base; and

ii) a second collector to output the power-sensing signal.

2. The amplifier circuit of claim 1 wherein the power-sensing signal is substantially proportional to the strength of the amplified radio frequency signal.

3. The amplifier circuit of claim 1 wherein the power-sensing signal is provided to an external circuit through a low-pass filter.

4. The amplifier circuit of claim 1 wherein the regulated DC source is coupled to the first base of the first transistor through a resistor.

5. The amplifier circuit of claim 1 wherein the first base is coupled to the second base through a low-pass filter.

6. The amplifier circuit of claim 1 wherein the output of the radio frequency power amplifier is coupled to the first base through a capacitor.

7. The amplifier circuit of claim 1 wherein the output of the radio frequency power amplifier is connected to an impedance-matching circuit which in turn is coupled to the first base of the first transistor.

8. The amplifier circuit of claim 1 comprising two equal sized transistors.

9. The amplifier circuit of claim 1 wherein the radio frequency power amplifier is fabricated with a Heterojunction Bipolar Transistor (HBT).

10. The amplifier circuit of claim 1 wherein the input radio frequency signal is modulated at a frequency in the range of 1MHz to 10GHz.

11. A power sensing circuit for sensing radio frequency signals, comprising:

a) a first transistor to perform as a detector diode, including

i) a first base to receive a first radio frequency input signal output, a second DC bias input signal from a regulated DC source, and a third power-sensing signal; and

ii) a first collector connected to the first base; and

b) a second transistor to amplify the DC component of the RF signal from the first base, including

i) a second base coupled to the first base; and

ii) a second collector to output the power-sensing signal, said power-sensing signal being coupled to the regulated DC source through a resistor.

12. The power sensing circuit of claim 11 wherein the power-sensing signal is substantially proportional to the strength of the first radio frequency signal.

13. The power sensing circuit of claim 11 wherein the power-sensing signal is provided to an external circuit through a low-pass filter.

14. The power sensing circuit of claim 11 wherein the regulated DC source is coupled to the first base of the first transistor through a resistor.

15. The power sensing circuit of claim 11 wherein the first base of the first transistor is coupled to the second base of the second transistor through a low-pass filter.

16. The power sensing circuit of claim 11 wherein the size of the first transistor is the same as the size of the second transistor.

17. A power sensing circuit for sensing radio frequency (RF) signals, comprising:

a) a first transistor to perform as a detector diode, including

i) a first base to receive a first radio frequency input signal output, a second DC bias signal from a regulated DC source coupled through a resistor, and a third power-sensing signal; and

ii) a first collector connected to the first base;

b) a second transistor to amplify the DC component of the RF signal from the first base, including

i) a second base connected to the first base through a low-pass filter; and

ii) a second collector to output the power-sensing signal to be coupled to the regulated DC source through a resistor, said power-sensing signal being substantially proportional to the strength of the first radio frequency input signal; and

c) an output port coupled to the second collector through a low-pass filter, to output the power-sensing signal.

18. The circuit of claim 17, further comprising a diode coupled between the regulated DC source and the second collector.

19. The circuit of claim 17, further comprising a capacitor coupled between the first collector and the second base.

20. The circuit of claim 17, wherein the power sensing signal comprises an average power.

21. The circuit of claim 20, wherein the power sensing signal is compared to a peak envelope of an RF signal to determine a PAR (peak to average ratio).

22. The circuit of claim 21, wherein a power amplifier is biased for high output when the PAR is high, the power amplifier is biased for higher efficiency when PAR is low.