AGC for slicer-based low power demodulator

• US 8,483,639 B2
• Filed: 05/06/2008
• Issued: 07/09/2013
• Est. Priority Date: 05/06/2008
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Lee, Chong U., Ekbal, Amal, Julian, David Jonathan, Shi, Jun
• Primary Examiner(s): VO, NGUYEN THANH
• Application Number:
  US12/116,155
• Publication Number:
  US 20090278606A1
• Time in Patent Office: 1,890 Days
• Field of Search: 455/232.1, 455/234.1, 455/234.2, 375/345
• US Class Current: 455/234.1
• CPC Class Codes: H03G 3/3078 Circuits generating control signals for digitally modulated signals

Abstract

An apparatus and method for performing automatic gain control in a receiver are disclosed. The apparatus may include an amplifier, and the gain control may be based on an output from the amplifier during a time period in which a target signal is not present at the output of the amplifier.

Claims

1. An apparatus for wireless communications, comprising:

an amplifier;

an automatic gain control configured to determine a gain for the amplifier based on an output from the amplifier during a time period in which a target signal is not present at the output of the amplifier; and

a slicer configured to sample the output from the amplifier, wherein the automatic gain control is further configured to determine the gain for the amplifier from the samples during the time period;

wherein the automatic gain control is further configured to;

process the samples;

compare the processed samples to a threshold; and

determine the gain for the amplifier based on the comparison; and

further wherein each of the samples output from the slicer comprises a first or second value, the automatic gain control being further configured to;

compare a percentage of samples having the first value to a threshold percentage during the time period; and

determine the gain for the amplifier based on the comparison.

2. The apparatus of claim 1 wherein the automatic gain control is further configured to determine the gain for the amplifier based on the output from the amplifier during a second time period in which the target signal is present at the output of the amplifier.

3. The apparatus of claim 1 wherein the slicer comprises a 1-bit slicer.

4. The apparatus of claim 1 wherein the first value comprises a logic state 1 and the second value comprises a logic state of 0.

5. The apparatus of claim 1 wherein the first value comprises a logic state of 0 and the second value comprises a logic state of 1.

6. The apparatus of claim 1 further comprising a second amplifier, wherein the automatic gain control is further configured to determine a gain for the second amplifier from the samples output from the slicer during the time period.

7. The apparatus of claim 6 wherein one of the amplifier and second amplifier comprises a low noise amplifier and the other one of the amplifier and second amplifier comprises a variable gain amplifier.

8. The apparatus of claim 1 wherein the amplifier comprises either a low noise amplifier or a variable gain amplifier.

9. An apparatus for wireless communications, comprising:

an amplifier;

an automatic gain control configured to determine a gain for the amplifier based on an output from the amplifier during a time period in which a target signal is not present at the output of the amplifier; and

a slicer configured to sample the output from the amplifier, wherein the automatic gain control is further configured to determine the gain for the amplifier from the samples during the time period, wherein the slicer is further configured to sample the output from the amplifier based on a threshold, and wherein the automatic gain control is further configured to determine the threshold for the slicer from the samples during the time period.

10. The apparatus of claim 9 wherein the automatic gain control is further configured to:

obtain a minimum required gain resolution;

recursively set minimum and maximum hypothetical gain parameters and a best hypothetical gain parameter based on system parameters until a difference between the minimum and maximum hypothetical gain parameters is equal to or less than the minimum required gain resolution; and

determine the gain for the amplifier based on the best hypothetical gain parameter.

11. An apparatus for wireless communications, comprising:

means for amplifying a target signal;

means for automatically controlling a gain for the amplifying means based on an output from the amplifying means during a time period in which the target signal is not present at the output of the amplifying means; and

means for sampling the output from the amplifying means, wherein the means for automatically controlling a gain for the amplifying means further comprises means for determining the gain for the amplifying means from the samples during the time period;

wherein the means for automatically controlling a gain of the amplifying means further comprises;

means for processing the samples output from the sampling means;

means for comparing the processed samples to a threshold; and

means for determining the gain for the amplifier based on the comparison; and

further wherein each of the samples output from the sampling means comprises a first or second value, the means for automatically controlling a gain of the amplifying means further comprising;

means for comparing a percentage of samples having the first value to a threshold percentage during the time period; and

means for determining the gain for the amplifying means based on the comparison.

12. The apparatus of claim 11 wherein the means for automatically controlling a gain for the amplifying means further comprises means for determining the gain for the amplifying means based on the output from the amplifying means during a second time period in which the target signal is present at the output of the amplifying means.

13. The apparatus of claim 11 wherein the sampling means comprises a slicer.

14. The apparatus of claim 13 wherein the slicer comprises a 1-bit slicer.

15. The apparatus of claim 11 wherein the first value comprises a logic state 1 and the second value comprises a logic state of 0.

16. The apparatus of claim 11 wherein the first value comprises a logic state of 0 and the second value comprises a logic state of 1.

17. The apparatus of claim 11 further comprising a second means for amplifying the target signal, wherein the means for automatically controlling a gain of the amplifying means further comprises means for determining a gain for the second amplifying means from the samples output from the sampling means during the time period.

18. The apparatus of claim 17 wherein one of the amplifying means and the second amplifying means comprises a low noise amplifier and the other one of the amplifying means and the second amplifying means comprises a variable gain amplifier.

19. The apparatus of claim 11 wherein the amplifying means comprises either a low noise amplifier or a variable gain amplifier.

20. An apparatus for wireless communications, comprising:

means for amplifying a target signal;

means for automatically controlling a gain for the amplifying means based on an output from the amplifying means during a time period in which the target signal is not present at the output of the amplifying means; and

means for sampling the output from the amplifying means, wherein the means for automatically controlling a gain for the amplifying means further comprises means for determining the gain for the amplifying means from the samples during the time period;

wherein the sampling means is configured to sample the outputs from the amplifying means based on a threshold, the apparatus further comprising means for determining the threshold for the sampling means from the samples output from the sampling means during the time period.

21. The apparatus of claim 20 wherein the means for automatically controlling a gain of the amplifying means further comprises:

means for obtaining a minimum required gain resolution;

means for recursively setting minimum and maximum hypothetical gain parameters and a best hypothetical gain parameter based on the system parameters until a difference between the minimum and maximum hypothetical gain parameters is equal to or less than the minimum required gain resolution; and

means for determining the gain for the amplifying means based on the best hypothetical gain parameter.

22. A method of automatic gain control, comprising:

amplifying a target signal with an amplifier;

automatically controlling a gain for the amplifier based on an output from the amplifier means during a time period in which the target signal is not present at the output of the amplifier and

sampling the output from the amplifier, wherein the automatic control of the gain further comprises determining the gain for the amplifier from the samples during the time period;

wherein the automatic control of the gain further comprises;

processing the samples;

comparing the processed samples to a threshold; and

determining the gain for the amplifier based on the comparison; and

further wherein each of the samples comprises a first or second value, the automatic control of the gain further comprises;

comparing a percentage of samples having the first value to a threshold percentage during the time period; and

determining the gain for the amplifier based on the comparison.

23. The method of claim 22 wherein the automatic control of the gain comprises determining the gain for the amplifier based on the output from the amplifier during a second time period in which the target signal is present at the output of the amplifier.

24. The method of claim 22 wherein the first value comprises a logic state 1 and the second value comprises a logic state of 0.

25. The method of claim 22 wherein the first value comprises a logic state of 0 and the second value comprises a logic state of 1.

26. The method of claim 22 further comprising a second amplifier, wherein the automatic control of the gain further comprises determining a gain for the second amplifier from the samples during the time period.

27. A method of automatic gain control, comprising:

amplifying a target signal with an amplifier;

automatically controlling a gain for the amplifier based on an output from the amplifier means during a time period in which the target signal is not present at the output of the amplifier; and

sampling the output from the amplifier, wherein the automatic control of the gain further comprises determining the gain for the amplifier from the samples during the time period;

wherein the sampling of the output from the amplifier is based on a threshold, and wherein the automatic control of the gain further comprises determining the threshold during the time period.

28. The method of claim 27 wherein the automatic control of the gain further comprises:

obtaining a minimum required gain resolution;

recursively setting minimum and maximum hypothetical gain parameters and a best hypothetical gain parameter based on system parameters until a difference between the minimum and maximum hypothetical gain parameters is equal to or less than the minimum required gain resolution; and

determining the gain for the amplifier based on the best hypothetical gain parameter.

29. A computer-program product for automatically controlling a gain of an amplifier, comprising:

a non-transitory computer-readable medium encoded with codes executable to;

amplify a target signal with an amplifier;

automatically control a gain for the amplifier based on an output from the amplifier during a time period in which a target signal is not present at the output of the amplifier; and

sample the output from the amplifier, wherein the automatic control of the gain comprises determining the gain for the amplifier from the samples during the time period;

wherein the automatic control of the gain further comprises;

processing the samples;

comparing the processed samples to a threshold; and

determining the gain for the amplifier based on the comparison; and

further wherein each of the samples comprises a first or second value, and the automatic control of the gain further comprises;

comparing a percentage of samples having the first value to a threshold percentage during the time period; and

determining the gain for the amplifier based on the comparison.

30. A headset, comprising:

an amplifier;

an automatic gain control configured to determine a gain for the amplifier based on an output from the amplifier during a time period in which a target signal is not present at the output of the amplifier;

a slicer configured to sample the output from the amplifier, wherein the automatic gain control is further configured to determine the gain for the amplifier from the samples during the time period;

wherein the automatic gain control is further configured to;

process the samples;

compare the processed samples to a threshold; and

determine the gain for the amplifier based on the comparison; and

further wherein each of the samples output from the slicer comprises a first or second value, the automatic gain control being further configured to;

compare a percentage of samples having the first value to a threshold percentage during the time period; and

determine the gain for the amplifier based on the comparison; and

a transducer configured to generate sound based on the target signal.

31. A watch, comprising:

an amplifier;

an automatic gain control configured to determine a gain for the amplifier based on an output from the amplifier during a time period in which a target signal is not present at the output of the amplifier;

a slicer configured to sample the output from the amplifier, wherein the automatic gain control is further configured to determine the gain for the amplifier from the samples during the time period;

wherein the automatic gain control is further configured to;

process the samples;

compare the processed samples to a threshold; and

determine the gain for the amplifier based on the comparison; and

further wherein each of the samples output from the slicer comprises a first or second value, the automatic gain control being further configured to;

compare a percentage of samples having the first value to a threshold percentage during the time period; and

determine the gain for the amplifier based on the comparison; and

a user interface configured to provide an indication based on the target signal.

32. A sensing device, comprising:

an amplifier;

an automatic gain control configured to determine a gain for the amplifier based on an output from the amplifier during a time period in which a target signal is not present at the output of the amplifier;

a slicer configured to sample the output from the amplifier, wherein the automatic gain control is further configured to determine the gain for the amplifier from the samples during the time period;

wherein the automatic gain control is further configured to;

process the samples;

compare the processed samples to a threshold; and

determine the gain for the amplifier based on the comparison; and

further wherein each of the samples output from the slicer comprises a first or second value, the automatic gain control being further configured to;

compare a percentage of samples having the first value to a threshold percentage during the time period; and

determine the gain for the amplifier based on the comparison; and

a sensor configured to generate data based on the target signal.