Power amplifier protection circuit and associated methods

• US 20060003711A1
• Filed: 06/30/2004
• Published: 01/05/2006
• Est. Priority Date: 06/30/2004
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Black Sand Technologies, Inc. (Qualcomm, Inc.)
• Inventors: Ouzillou, Mendy M., Bocock, Ryan M.
• Granted Patent: US 7,751,783 B2
• Time in Patent Office: Days
• US Class Current: 455/115.100
• CPC Class Codes: H03F 1/52 Circuit arrangements for protecting such amplifiers monitoring arrangements G01R31/28; increasing reliability in communication systems, e.g. using redundancy H04B1/74
• CPC Class Codes: H03F 2200/468 the temperature being sensed
• CPC Class Codes: H04B 1/036 Cooling arrangements

Abstract

In a power amplifier, techniques are provided for protecting the power amplifier from temperature extremes resulting from conditions such as load mismatches. After sensing the temperature of the power amplifier, the operation of the RF power amplifier is controlled accordingly. In one example, the power amplifier is shut down when the sensed temperature reaches a threshold value, which can be set to a value just below the point where permanent damage would occur. In another example, when a threshold temperature is reached, the operation of the power amplifier is changed, to prevent the temperature of the power amplifier from rising to a level that would damage the power amplifier.

Claims

1. A circuit comprising:

an RF power amplifier;

a temperature sensor for sensing the temperature of the RF power amplifier; and

a control circuit, wherein the control circuit changes the operation of the RF power amplifier in response to the sensed temperature reaching a threshold value.

2. The circuit of claim 1, wherein the control circuit shuts down the RF power amplifier in response to the sensed temperature reaching a threshold value.

3. The circuit of claim 1, wherein the RF power amplifier generates an output signal, and wherein the control circuit decreases the power of the output signal in response to the sensed temperature reaching a threshold value.

4. The circuit of claim 1, wherein the RF power amplifier generates an output signal having a duty cycle, and wherein the control circuit decreases the duty cycle in response to the sensed temperature reaching a threshold value.

5. The circuit of claim 1, wherein the circuit is used in a mobile communication system, wherein the control circuit drops a call in response to the threshold value being reached.

6. The circuit of claim 1, wherein the control circuit conveys a message to a user of the circuit in response to the sensed temperature reaching a threshold value.

7. The circuit of claim 6, wherein the message instructs the user to move the circuit.

8. The circuit of claim 1, wherein the control circuit determines whether the sensed temperature reaches the threshold value by comparing a temperature dependent signal with a reference signal.

9. The circuit of claim 8, wherein the reference signal is a temperature independent signal.

10. The circuit of claim 8, further comprising a bandgap reference circuit, wherein the reference signal is derived from the bandgap reference circuit.

11. The circuit of claim 1, wherein the control circuit determines when the sensed temperature reaches a second threshold value.

12. The circuit of claim 11, wherein the control circuit shuts down the RF power amplifier when the sensed temperature reaches the second threshold value.

13. The circuit of claim 1, wherein the circuit is formed on an integrated circuit.

14. The circuit of claim 1, wherein the circuit is formed on a complementary metal oxide semiconductor (CMOS) integrated circuit.

15. A circuit comprising:

an RF power amplifier for generating an RF output signal;

a temperature sensor for sensing the temperature of the RF power amplifier;

control circuitry coupled to the temperature sensor for comparing one or more temperature dependent signals with first and second reference signals, wherein the control circuitry determines when the sensed temperature reaches a first threshold temperature and when the sensed temperature reaches a second threshold temperature based on the comparisons.

16. The circuit of claim 15, wherein the control circuitry takes a first action when the sensed temperature reaches the first threshold temperature.

17. The circuit of claim 16, wherein the first action involves decreasing the power level of the RF output signal.

18. The circuit of claim 16, wherein the first action involves conveying a message to a user of the circuit.

19. The circuit of claim 15, wherein the control circuitry takes a second action when the sensed temperature reaches the second threshold temperature.

20. The circuit of claim 19, wherein the control circuitry causes the RF power amplifier to shut down when the sensed temperature reaches the second threshold temperature.

21. The circuit of claim 15, wherein the first and second reference signals are temperature independent signals.

22. The circuit of claim 21, further comprising a first bandgap reference circuit, wherein the first reference signal is derived from the bandgap reference circuit.

23. The circuit of claim 22, further comprising a second bandgap reference circuit, wherein the second reference signal is derived from the bandgap reference circuit.

24. The circuit of claim 15, wherein the RF power amplifier is formed on an integrated circuit.

25. The circuit of claim 15, wherein the circuit is formed on a complementary metal oxide semiconductor (CMOS) integrated circuit.

26. An integrated circuit comprising:

an RF power amplifier circuit formed on the integrated circuit for generating an RF output signal; and

a temperature sensor formed on the integrated circuit for sensing the temperature of the integrated circuit, wherein the operation of the RF power amplifier circuit is changed when a sensed temperature reaches a threshold value.

27. The integrated circuit of claim 26, wherein the RF power amplifier is disabled in response to a sensed temperature reaching a threshold value.

28. The integrated circuit of claim 26, wherein the power level of the RF output signal is decreased in response to a sensed temperature reaching a threshold value.

29. The integrated circuit of claim 26, wherein the duty cycle of the RF output signal is decreased in response to a sensed temperature reaching a threshold value.

30. The integrated circuit of claim 26, further comprising a control circuit, wherein the control circuit determines whether a sensed temperature reaches the threshold value by comparing a temperature dependent signal with a reference signal.

31. The integrated circuit of claim 30, wherein the reference signal is a temperature independent signal.

32. The integrated circuit of claim 30, wherein the control circuit determines whether a sensed temperature reaches a second threshold value by comparing a temperature dependent signal with a reference signal, wherein the second threshold value is higher than the first threshold value.

33. The integrated circuit of claim 32, wherein the control circuit shuts down the RF power amplifier in response to the sensed temperature reaching the second threshold value.

34. The integrated circuit of claim 30, wherein the reference signal is provided as an input to the integrated circuit.

35. The integrated circuit of claim 34, wherein the reference signal is provided by a baseband controller.

36. The integrated circuit of claim 26, further comprising a bandgap reference circuit.

37. The integrated circuit of claim 36, wherein the bandgap reference circuit generates a temperature independent reference signal.

38. The integrated circuit of claim 37, further comprising a control circuit, wherein the control circuit determines whether a sensed temperature reaches the threshold value by comparing a temperature dependent signal with the temperature independent reference signal generated by the bandgap reference circuit.

39. The integrated circuit of claim 26, wherein the integrated circuit is formed on a complementary metal oxide semiconductor (CMOS) device.