RF power detector

• US 6,927,630 B2
• Filed: 09/29/2003
• Issued: 08/09/2005
• Est. Priority Date: 09/12/2000
• Status: Expired due to Term

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Silicon Laboratories Incorporated
• Inventors: Niknejad, Ali M., Welland, David R., Paul, Susanne A., Dupuis, Timothy J.
• Primary Examiner(s): Shingleton, Michael B
• Application Number:
  US10/673,956
• Publication Number:
  US 20040075499A1
• Time in Patent Office: 680 Days
• Field of Search: 330/254, 330/133, 330/134, 330/285, 327/306, 327/360, 327/323
• US Class Current: 330/254
• CPC Class Codes: H01L 2223/6644 Packaging aspects of high-frequency amplifiers
• CPC Class Codes: H01L 2224/0401 Bonding areas specifically adapted for bump connectors, e.g. under bump metallisation [UBM]
• CPC Class Codes: H01L 2224/16 of an individual bump connector
• CPC Class Codes: H01L 2224/16227 the bump connector connecting to a bond pad of the item
• CPC Class Codes: H01L 2224/16235 the bump connector connecting to a via metallisation of the item
• CPC Class Codes: H01L 23/645 Inductive arrangements H01L23/647, H01L23/66 take precedence
• CPC Class Codes: H01L 23/66 High-frequency adaptations
• CPC Class Codes: H01L 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 2924/13091 Metal-Oxide-Semiconductor Field-Effect Transistor [MOSFET]
• CPC Class Codes: H01L 2924/15192 Resurf arrangement of the internal vias
• CPC Class Codes: H01L 2924/15311 being a ball array, e.g. BGA
• CPC Class Codes: H01L 2924/3011 Impedance
• CPC Class Codes: H03F 1/02 Modifications of amplifiers to raise the efficiency, e.g. gliding Class A stages, use of an auxiliary oscillation
• CPC Class Codes: H03F 2200/387 A circuit being added at the output of an amplifier to adapt the output impedance of the amplifier
• CPC Class Codes: H03F 2200/391 the output circuit of an amplifying stage comprising an LC-network
• CPC Class Codes: H03F 2200/451 the amplifier being a radio frequency amplifier
• CPC Class Codes: H03F 3/195 in integrated circuits
• CPC Class Codes: H03F 3/211 using a combination of several amplifiers H03F3/60 takes precedence
• CPC Class Codes: H03F 3/2171 with field-effect devices H03F3/2173 - H03F3/2178 take precedence
• CPC Class Codes: H03F 3/2173 of the bridge type
• CPC Class Codes: H03F 3/2176 : Class E amplifiers
• CPC Class Codes: H03F 3/24 : of transmitter output stages
• CPC Class Codes: H03F 3/30 : Single-ended push-pull [SEPP] amplifiers single-ended sense amplifiers G11C7/067; Phase-splitters therefor
• CPC Class Codes: H03F 3/45179 : using MOSFET transistors as the active amplifying circuit H03F3/45278 takes precedence
• CPC Class Codes: H03F 3/72 : Gated amplifiers, i.e. amplifiers which are rendered operative or inoperative by means of a control signal
• CPC Class Codes: H03K 17/04163 : in field-effect transistor switches
• CPC Class Codes: H03K 17/6872 : using complementary field-effect transistors
• CPC Class Codes: Y10S 257/904 : with passive components,, e.g. polysilicon resistors

Abstract

A method and apparatus is provided for detecting the output power of an RF power amplifier for purposes of controlling the output power. A circuit for generating an output power control signal includes a power detector to detect the output power of an RF power amplifier. A variable gain amplifier is coupled to the power detector for amplifying the output of the power detector. The value of the generated control signal is a function of the gain of the variable gain amplifier.

Claims

1. A method of controlling the output power of an RF power amplifier comprising:

generating a power detection signal relating to the output power of an RF power amplifier;

amplifying the power detection signal using a variable gain amplifier;

generating a gain control signal for setting the gain of the variable gain amplifier, wherein the gain control signal is generated using the output of the variable gain amplifier; and

using the gain control signal to generate a power control signal for use by the RF power amplifier in setting the output power level of the RF power amplifier.

2. The method of claim 1, wherein the gain control signal is related to the envelope of the output or the variable gain amplifier.

3. The method of claim 1, wherein the gain control signal is generated by sensing the output of the variable gain amplifier.

4. The method of claim 1, wherein the gain control signal is generated by using a peak detector on the output of the variable gain amplifier.

5. The method of claim 3, wherein the gain control signal is generated using the sensed output of the variable gain amplifier and a reference signal.

6. The method of claim 1, wherein the variable gain amplifier is a multi-stage amplifier.

7. The method of claim 6, wherein the gain of each stage of the variable gain amplifier is set by the gain control signal.

8. An RF power amplifier comprising:

an amplifier;

a power detector coupled to the output of the amplifier for detecting the output power of the amplifier.

a variable gain amplifier having an input and an output, wherein the input is coupled to the power detector;

a first circuit coupled to the output of the variable gain amplifier for generating a gain control signal, wherein the gain control signal controls the gain of the variable gain amplifier; and

a second circuit coupled to the gain control signal for generating a power control signal based on the gain control signal.

9. The RE power amplifier of claim 8, wherein the power control signal is coupled to the RF power amplifier for controlling the output power of the RF power amplifier.

10. The RF power amplifier of claim 8, wherein the power detector is comprised of a directional coupler.

11. The RF power amplifier of claim 8, wherein the variable gain amplifier is a multi-stage amplifier.

12. The RF power amplifier of claim 11, wherein the gain of each stage of the multi-stage amplifier is controlled by the gain control signal.

13. The RF power amplifier of claim 8, wherein the first circuit includes a peak detector coupled to the output of the variable gain amplifier.

14. The RF power amplifier of claim 13, wherein the first circuit includes an op-amp coupled to an output of the peak detector and to a reference signal.

15. The RF power amplifier of claim 8, wherein the second circuit includes a conditioning circuit.

16. A method of controlling the output power of an RF power amplifier comprising:

detecting the output power of an RF power amplifier;

providing a variable gain amplifier that approximate a logarithmic amplifier, wherein the gain of the variable gain amplifier is controlled by a gain control signal, and wherein the gain control signal is related to the variable gain amplifier;

using the gain control signal to generate a power control signal, wherein the power control signal has a generally linear relationship with the output power of the RF power amplifier on a log scale.

17. The method of claim 16, wherein the variable gain amplifier is a multi-stage amplifier.

18. The method of claim 17, wherein the gain of each stage of the variable gain amplifier is set by the gain control signal.

19. The method of claim 16, wherein the power control signal is related to the gain of the variable gain amplifier.

20. The method of claim 16, wherein the gain control signal is generated using the output of the variable gain amplifier.

21. The method of claim 16, wherein the gain control signal is related to the envelope of the output of the variable gain amplifier.

22. The method of claim 16, wherein the gain control signal is generated by sensing the output of the variable gain amplifier.

23. The method of claim 22, wherein the gain control signal is generated using the sensed output of the variable gain amplifier and a reference signal.

24. The method of claim 16, wherein the gain control signal is generated by using a peak detector on the output of the variable gain amplifier.

25. A method of controlling the output power of an RF power amplifier comprising:

generating a power detection signal relating to the output power of an RF power amplifier;

amplifying the power detection signal using a variable gain amplifier;

setting the gain of the variable gain amplifier using a gain control signal, wherein the gain control signal is generated using the output of the variable in amplifier;

generating a power control signal for use by the RF power amplifier in setting the output power level of the RF power amplifier, wherein the power control signal is generated using the gain control signal.

26. The method of claim 25, wherein the gain control signal is related to the envelope of the output of the variable gain amplifier.

27. The method of claim 25, wherein the gain control signal is generated by sensing the output of the variable gain amplifier.

28. The method claim 25, wherein the gain control signal is generated by using a peak detector on the output of the variable gain amplifier.

29. The method of claim 27, wherein the gain control signal is generated using the sensed output of the variable gain amplifier and a reference signal.

30. The method of claim 25, wherein the variable gain amplifier is a multi-stage amplifier.

31. The method of claim 30, wherein the gain of each stage of the variable gain amplifier is set by the gain control signal.