LOW LATENCY FREQUENCY SWITCHING

• US 20080212553A1
• Filed: 10/25/2007
• Published: 09/04/2008
• Est. Priority Date: 10/31/2002
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Shiu, Da-shan, Zhang, Li, Malonado, David, Dhaliwal, Upkar, Sy, Eugene
• Granted Patent: US 8,565,121 B2
• Time in Patent Office: Days
• US Class Current: 370/343
• CPC Class Codes: H03G 3/3036 in high-frequency amplifiers or in frequency-changers H03G3/3052, H03G3/32, H03G3/34 take precedence

Abstract

Techniques for improved low latency frequency switching are disclosed. In one embodiment, a controller receives a frequency switch command and generates a frequency switch signal at a time determined in accordance with a system timer. In another embodiment, gain calibration is initiated subsequent to the frequency switch signal delayed by the expected frequency synthesizer settling time. In yet another embodiment, DC cancellation control and gain control are iterated to perform gain calibration, with signaling to control the iterations without need for processor intervention. Various other embodiments are also presented. Aspects of the embodiments disclosed may yield the benefit of reducing latency during frequency switching, allowing for increased measurements at alternate frequencies, reduced time spent on alternate frequencies, and the capacity and throughput improvements that follow from minimization of disruption of an active communication session and improved neighbor selection.

Claims

1. A receiver, comprising:

a synthesizer tunable to at least first and second frequencies respectively corresponding to at least first and second communication modes; and

a receive chain configured to transition between the at least first and second communication modes prior to the synthesizer respectively settling between the at least first and second frequencies.

2. The receiver of claim 1, wherein the synthesizer is further configured to transition from and back to the first communication mode during a time gap in the first communication system.

3. The receiver of claim 2, wherein the receive chain is further configured to calibrate the gain of the receive chain during the time gap.

4. The receiver of claim 1, wherein the receive chain is further configured to transition between the at least first and second communication modes according to a time delay after the synthesizer tunes from the first frequency to the second frequency.

5. The receiver of claim 1, wherein the receive chain is further configured to store a configuration of the first communication mode before transitioning to the second communication mode and to retrieve the configuration for use in returning to the first communication mode.

6. A dual-mode receiver, comprising:

a retunable synthesizer alternatingly configurable between a first communication mode corresponding to a first frequency and a second communication mode corresponding to a second frequency; and

a reconfigurable receive chain alternatingly configurable between the first communication mode and the second communication mode, the synthesizer and receive chain substantially concurrently configurable such that the receive chain is reconfigured before the synthesizer settles.

7. The dual-mode receiver of claim 6, wherein the receiver further comprises a controller for storing and retrieving a configuration of the first communication mode for use in reconfiguring the receive chain upon return to the first communication mode.

8. The dual-mode receiver of claim 6, wherein the receiver further comprises a controller configured to manage completion of the reconfiguration of the receive chain prior to the synthesizer settling.

9. The dual-mode receiver of claim 6, wherein the receiver further comprises a controller configured to manage calibration of the gain of the receive chain after the synthesizer settles.

10. The dual-mode receiver of claim 6, wherein the receiver further comprises a controller configured to manage transition of the synthesizer and the receive chain from the first communication mode to the second communication mode and return to the first communication mode during a time gap in the first communication mode.

11. A computer-readable medium including computer-executable instructions for causing a computer to changing communication modes, comprising:

instructions for causing the computer to retune from a first frequency to a second frequency respectively corresponding to a first communication mode and a second communication mode; and

instructions for causing the computer to reconfigure a receive chain from the first communication mode to the second communication mode before the second frequency settles.

12. The computer-readable medium of claim 11, further comprising computer-executable instructions for causing the computer to retune from the second frequency corresponding to the second communication mode to the first frequency corresponding to the first communication mode, wherein the retuning from the first communication mode to the second communication mode and retuning from the second communication mode to the first communication mode occurs during a time gap in the first communication system.

13. The computer-readable medium of claim 12, further comprising computer-executable instructions for causing the computer to store a configuration of the first communication mode for use in returning from the second communication mode to the first communication mode.

14. The computer-readable medium of claim 11, further comprising computer-executable instructions for causing the computer to calibrate the gain of the receive chain when the receive chain is reconfigured to the second communication mode and the second frequency has settled.

15. The computer-readable medium of claim 11, wherein the computer-executable instructions for causing the computer to reconfigure a receive chain further comprises computer-executable instructions for causing the computer to time the reconfiguration of the receive chain to complete concurrently with or prior to the second frequency settling.

16. A method for monitoring a communication mode, comprising:

determining a time gap of a first communication mode;

retuning at a beginning of the time gap from a first frequency corresponding to the first communication mode to a second frequency corresponding to the second communication mode; and

reconfiguring a receiver from the first communication mode to the second communication mode before the second frequency settles.

17. The method of claim 16, further comprising retuning from the second frequency corresponding to the second communication mode to the first frequency corresponding to the first communication mode, wherein the retuning from the first communication mode to the second communication mode and retuning from the second communication mode to the first communication mode occurs during the time gap in the first communication system.

18. The method of claim 17, further comprising storing and retrieving a configuration of the first communication mode for use in reconfiguring the receiver upon return to the first communication mode.

19. The method of claim 16, further comprising calibrating the gain of the receiver after the second frequency settles.

20. The method of claim 16, wherein reconfiguring the receiver further comprises timing the reconfiguration of the receiver to complete concurrently with or prior to the second frequency settling.

21. A computer-readable medium including computer-executable instructions comprising:

instructions for causing a computer to determine a time gap of a first communication mode;

instructions for causing the computer to retune at a beginning of the time gap from a first frequency corresponding to the first communication mode to a second frequency corresponding to the second communication mode; and

instructions for causing the computer to reconfigure a receiver from the first communication mode to the second communication mode before the second frequency settles.