Method to track analog gain step magnitudes online during operation of wireless mobile devices

• US 7,873,340 B2
• Filed: 03/10/2006
• Issued: 01/18/2011
• Est. Priority Date: 03/10/2005
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Krishnamoorthi, Raghuraman, Li, Linbo, Ling, Fuyun
• Primary Examiner(s): Nguyen; Duc M
• Application Number:
  US11/373,369
• Publication Number:
  US 20060215793A1
• Time in Patent Office: 1,775 Days
• Field of Search: 455/232.1, 455/234.1, 455/241.1, 455/245.1, 455/245.2, 455/250.1, 455/251.1, 375/345
• US Class Current: 455/234.1
• CPC Class Codes: H03F 1/0205 in transistor amplifiers
• CPC Class Codes: H03F 2200/294 the amplifier being a low noise amplifier [LNA]
• CPC Class Codes: H03F 2200/372 Noise reduction and elimination in amplifier
• CPC Class Codes: H03F 3/24 of transmitter output stages
• CPC Class Codes: H03G 1/0088 using discontinuously variable devices, e.g. switch-operated
• CPC Class Codes: H03G 3/3052 in bandpass amplifiers (H.F. or I.F.) or in frequency-changers used in a (super)heterodyne receiver H03G3/32, H03G3/34 take precedence
• CPC Class Codes: H03G 3/3068 Circuits generating control signals for both R.F. and I.F. stages
• CPC Class Codes: H04B 1/109 by improving strong signal performance of the receiver when strong unwanted signals are present at the receiver input

Abstract

Systems and methods are provided for tracking and compensating for analog gain mismatches or changes in a receiver. In an embodiment, a method is provided to track analog gain step magnitudes during operation of a device. The method includes employing an error signal between an automatic gain control (AGC) output and a reference level as input to a gain step magnitude tracking component. This also includes determining at least one compensation value from the AGC output to update a nominal gain step magnitude that tracks an actual gain step magnitude.

Claims

1. A method to track gain step magnitudes in an automatic gain control (AGC) module of a receiver, the method comprising:

storing one or more nominal gain step magnitudes for at least one amplifier;

adjusting a gain state of the at least one amplifier in one or more stored nominal gain steps;

monitoring output energy of the AGC module after at least one gain state adjustment;

calculating a mismatch between nominal gain step magnitudes and actual gain step magnitudes of the at least one amplifier based in part on the output energy of the AGC module; and

updating the stored one or more nominal gain step magnitudes to track the actual gain step magnitudes of the at least one amplifier by multiplying the gain step magnitude mismatch by a loop gain, the loop gain based in part on power fluctuation across a received signal.

2. The method of claim 1, further comprising calculating gain step magnitude mismatch after N gain state adjustments, where N is an integer greater than or equal to 2.

3. The method of claim 1, further comprising analyzing a noisy observation of the gain step magnitude mismatch.

4. The method of claim 3, further comprising applying multiplying the gain step magnitude mismatch by a lower loop gain to suppress observation noise of the gain step magnitude mismatch.

5. The method of claim 1, wherein the received signal includes on one or more OFDM symbols.

6. The method of claim 1, further comprising calculating the gain step magnitude mismatch as a function of a difference between a reference level and output energy of the AGC module.

7. The method of claim 1, further comprising employing a first order loop to track the actual gain step magnitudes.

8. The method of claim 1, further comprising updating at least one register that stores the nominal gain step magnitudes.

9. The method of claim 1, further comprising storing output energy and loop gain for an update period before a gain state adjustment.

10. An automatic gain control (AGC) module for a receiver, comprising:

an analog amplifier for amplifying an input RF signal, the analog amplifier configured to operate at a plurality of discrete analog gain states having different gain magnitudes;

a digital variable gain amplifier (DVGA) operably coupled to the analog amplifier for amplifying or attenuating digitized output of the analog amplifier to maintain an output signal of the AGC module at a substantially constant level by varying gain of the DVGA by one or more digital gain steps having nominal gain step magnitudes;

a gain tracking component operably coupled to the analog amplifier and DVGA, the gain tracking component configured to (i) monitor energy of the output signal of the AGC module and (ii) adjust gain state of the analog amplifier by one or more analog gain steps having nominal gain step magnitudes when energy of the output signal of the AGC module is above or below a reference level; and

a gain step magnitude component operably coupled to the gain tracking component, the gain step magnitude component configured to (i) store one or more nominal gain step magnitudes, (ii) after one or more analog gain state adjustments, calculate a mismatch between nominal gain step magnitudes and actual gain step magnitudes of the AGC module, and (iii) update the stored one or more nominal gain step magnitudes to track the actual gain step magnitudes based on the gain step magnitude mismatch.

11. The module of claim 10, further comprising a low noise amplifier (LNA) or a mixer to receive one or more analog gain state switching commands from gain tracking component and adjusts the analog gain states based in part on the commands.

12. The module of claim 10, wherein the gain step magnitude component further configured to calculate gain step magnitude mismatch after at least two analog gain state adjustments.

13. The module of claim 10, wherein the gain step magnitude component further configured to multiply the gain step magnitude mismatch by a loop gain to produce one or more updated nominal gain step magnitudes that track actual gain step magnitudes.

14. The module of claim 13, wherein the gain step magnitude component employs a first order loop to track the actual gain step magnitudes.

15. The module of claim 10, further comprising at least one analog to digital converter operably coupled to the analog amplifier for digitizing output of the analog amplifier.

16. The module of claim 10, wherein the gain step magnitude module comprises one or more registers for storing and updating one or more nominal gain step magnitudes.

17. The module of claim 10, wherein the gain step magnitude component is further configured to calculate the gain step magnitude mismatch as a function of a difference between a reference level and output energy of the AGC module.

18. The module of claim 10, wherein the gain tracking component comprises a feedback that is applied between the analog amplifier and DVGA to control overall loop gain in the AGC module.

19. The module of claim 10, wherein the gain step magnitude mismatch is a noisy observation of mismatch between nominal gain step magnitudes and actual gain step magnitudes of the AGC module.

20. The module of claim 10, further comprising a machine readable medium having machine executable instructions stored thereon to execute the gain tracking component or the gain step magnitude component.

21. A system for determining analog gain step magnitude in a receiver, comprising:

means for storing one or more nominal gain step magnitudes for at least one amplifier;

means for adjusting gain state of at least one amplifier in one or more nominal gain steps;

means for monitoring output energy of the AGC module after at least one gain state adjustment of at least one amplifier;

means for calculating a mismatch between nominal gain step magnitudes and actual gain step magnitudes of at least one amplifier based in part on the output energy of the AGC module; and

means for updating the stored one or more nominal gain step magnitudes to track the actual gain step magnitudes based on the calculated the gain step magnitude mismatch.

22. The system of claim 21, further comprising means for calculating gain step magnitude mismatch after N gain state adjustments, where N is an integer greater than or equal to 2.

23. The system of claim 21, further comprising means for analyzing a noisy observation of the gain step magnitude mismatch.

24. The system of claim 21, further comprising means for multiplying the gain step magnitude mismatch by a loop gain to produce an updated nominal gain step magnitude for the at least one amplifier, the loop gain is based in part on power fluctuation across a received signal.

25. The system of claim 24, wherein the received signal includes on one or more OFDM symbols.

26. The system of claim 21, further comprising means for multiplying the gain step magnitude mismatch by a lower loop gain to suppress observation noise of the gain step magnitude mismatch.

27. The system of claim 21, further comprising means for calculating the gain step magnitude mismatch as a function of a difference between a reference level and output energy of the AGC module.

28. The system of claim 21, further comprising means for employing a first order loop to track the actual gain step magnitudes.

29. The system of claim 21, further comprising means for updating at least one register that stores the nominal gain step magnitudes.

30. The system of claim 21, further comprising means for storing output energy and loop gain for an update period before a gain state adjustment.

31. A non-transitory machine readable medium having machine executable instructions stored thereon for controlling operation of a receiver in a wireless communication device, the medium comprising:

instructions for storing in a data storage medium of the wireless communication device one or more nominal gain step magnitudes for at least one amplifier of an automatic gain control (AGC) module of the receiver;

instructions for adjusting gain state of at least one amplifier in one or more stored nominal gain steps;

instructions for tracking an output energy from the AGC module after at least one gain state adjustment of the amplifier;

instructions for calculating a mismatch between nominal gain step magnitudes and actual gain step magnitudes of the amplifier based in part on the output energy from the AGC module; and

instructions for updating the stored one or more nominal gain step magnitudes to track the actual gain step magnitudes by multiplying the gain step magnitude mismatch by a loop gain, the loop gain based in part on power fluctuation across a received signal.

32. The medium of claim 31, further comprising instructions for calculating gain step magnitude mismatch after N gain state adjustments, where N is an integer greater than or equal to 2.

33. The medium of claim 31, further comprising instructions for analyzing a noisy observation of the gain step magnitude mismatch.

34. The medium of claim 31, wherein the received signal includes on one or more OFDM symbols.

35. The medium of claim 31, further comprising instructions for multiplying the gain step magnitude mismatch by a lower loop gain to suppress observation noise of the gain step magnitude mismatch.

36. The medium of claim 31, further comprising instructions for calculating the gain step magnitude mismatch as a function of a difference between a reference level and output energy of the AGC module.

37. The medium of claim 31, further comprising instructions for employing a first order loop to track the actual gain step magnitudes.

38. The medium of claim 31, further comprising instructions for updating at least one register that stores the nominal gain step magnitudes.

39. The medium of claim 31, further comprising instructions for storing output energy and loop gain for an update period before a gain state adjustment.

40. A wireless communications device, comprising:

an automatic gain control (AGC) module comprising at least one amplifier;

a memory configured to store nominal gain step magnitudes for the at least one amplifier; and

a processor configured to

monitor output energy of AGC module,

adjust gain state of the at least one amplifier by one or more gain steps having nominal gain step magnitudes when output energy of AGC module is above or below a reference level,

calculate a mismatch between nominal gain step magnitudes and actual gain step magnitudes of the AGC module, and

update the one or more nominal gain step magnitudes stored in the memory to track the actual gain step magnitudes by multiplying the gain step magnitude mismatch by a loop gain, the loop gain based in part on power fluctuation across a received signal.

41. The device of claim 40, wherein the processor further configured to calculate gain step magnitude mismatch after N gain state adjustments, where N is an integer greater than or equal to 2.

42. The device of claim 40, wherein the processor further configured to analyze a noisy observation of the gain step magnitude mismatch.

43. The device of claim 40, wherein the received signal includes on one or more OFDM symbols.

44. The device of claim 40, wherein the processor further configured to multiply the gain step magnitude mismatch by a lower loop gain to suppress observation noise of the gain step magnitude mismatch.

45. The device of claim 40, wherein the processor further configured to calculate the gain step magnitude mismatch as a function of a difference between a reference level and output energy of the AGC module.

46. The device of claim 40, wherein the processor further configured to employ a first order loop to track the actual gain step magnitudes.

47. The device of claim 40, wherein the processor further configured to update at least one register of the memory that stores the nominal gain step magnitudes.

48. The device of claim 40, wherein the processor further configured to store in the memory output energy and loop gain for an update period before a gain state adjustment.