Variable bandwidth automatic gain control

• US 20070147556A1
• Filed: 03/06/2006
• Published: 06/28/2007
• Est. Priority Date: 11/09/2005
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Via Telecom Inc. (VIA Technologies)
• Inventors: Kang, Insung, Tandon, Tarun
• Granted Patent: US 7,596,193 B2
• Time in Patent Office: Days
• US Class Current: 375/345
• CPC Class Codes: H03G 3/3078 Circuits generating control signals for digitally modulated signals

Abstract

Provided is automatic gain control (AGC) in which a feedback filter has a parameter that is changed based on information regarding data-packet boundaries. In one representative embodiment, the bandwidth of the filter temporarily is increased, or the time constant of the AGC filter temporarily is decreased, within a vicinity of each actual or potential packet boundary.

Claims

1. A method of controlling gain in a signal receiver, comprising:

(a) applying a specified gain to an incoming signal, thereby providing a gain-adjusted signal;

(b) measuring strength of the gain-adjusted signal;

(c) generating a control signal by filtering a signal that is based on the strength of the gain-adjusted signal;

(d) controlling the specified gain based on the control signal;

(e) processing the gain-adjusted signal to identify information regarding data-packet boundaries; and

(f) altering a parameter of the filtering in step (c) based on the information regarding data-packet boundaries.

2. A method according to claim 1, wherein said altering step (f) comprises temporarily changing a bandwidth of the filtering within a vicinity of the data-packet boundaries.

3. A method according to claim 2, wherein the bandwidth of the filtering is temporarily increased within the vicinity of the data-packet boundaries.

4. A method according to claim 3, wherein both an amount of increase in the bandwidth and a duration of the increase are fixed in advance at constant values for all of the data-packet boundaries.

5. A method according to claim 3, wherein the control signal represents a comparison of the strength of the gain-adjusted signal to a target signal strength, wherein a duration of the increase is a fraction of a data packet interval, and wherein the increase in the bandwidth is sufficient to achieve the target signal strength in response to a transmission boundary by completion of the duration of the increase.

6. A method according to claim 1, wherein the incoming signal is synchronous.

7. A method according to claim 1, wherein the parameter of the filtering is altered in step (f) based on an expectation regarding behaviors of plural different transmitters.

8. A method according to claim 1, wherein the altering step (f) is based on identified data-packet boundaries that are different for each of plural different transmitters.

9. A method according to claim 1, wherein the control signal represents a comparison of the strength of the gain-adjusted signal to a target signal strength.

10. A method according to claim 1, wherein the incoming signal has been received across a communication channel.

11. An apparatus for controlling gain in a signal receiver, comprising components configured to:

(a) a variable-gain component that receives and applies a specified gain to an incoming signal, thereby providing a gain-adjusted signal;

(b) a detector coupled to an output of the variable-gain component that measures strength of the gain-adjusted signal;

(c) a filter, coupled to an output of the detector, that generates a control signal by filtering a signal that is based on the strength of the gain-adjusted signal, wherein the specified gain is controlled based on the control signal; and

(d) a signal-processing section that processes the gain-adjusted signal to identify information regarding data-packet boundaries; and

(e) an adjustment module, coupled to the signal-processing section, that alters a parameter of the filter based on the information regarding data-packet boundaries.

12. An apparatus according to claim 11, wherein said adjustment module temporarily changes a bandwidth of the filtering within a vicinity of the data-packet boundaries.

13. An apparatus according to claim 12, wherein the bandwidth of the filtering is temporarily increased within the vicinity of the data-packet boundaries.

14. An apparatus according to claim 13, wherein both an amount of increase in the bandwidth and a duration of the increase are fixed in advance at constant values for all of the data-packet boundaries.

15. An apparatus according to claim 13, wherein the control signal represents a comparison of the strength of the gain-adjusted signal to a target signal strength, wherein a duration of the increase is a fraction of a data packet interval, and wherein the increase in the bandwidth is sufficient to achieve the target signal strength in response to a transmission boundary by completion of the duration of the increase.

16. An apparatus according to claim 11, wherein the incoming signal is synchronous.

17. An apparatus according to claim 11, wherein the parameter of the filtering is altered by said adjustment module based on an expectation regarding behaviors of plural different transmitters.

18. An apparatus according to claim 11, wherein the parameter of the filtering is altered by said adjustment module based on identified data-packet boundaries that are different for each of plural different transmitters.

19. An apparatus according to claim 11, wherein the control signal represents a comparison of the strength of the gain-adjusted signal to a target signal strength.

20. An apparatus according to claim 11, wherein the incoming signal has been received across a communication channel.

21. An apparatus for controlling gain in a signal receiver, comprising:

(a) means for applying a specified gain to an incoming signal, thereby providing a gain-adjusted signal;

(b) means for measuring strength of the gain-adjusted signal;

(c) means for generating a control signal by filtering a signal that is based on the strength of the gain-adjusted signal;

(d) means for controlling the specified gain based on the control signal;

(e) means for processing the gain-adjusted signal to identify information regarding data-packet boundaries; and

(f) means for altering a parameter of the filtering by said means (c) based on the information regarding data-packet boundaries.