Method and system for power management for a frequency synthesizer in a GNSS receiver chip

• US 9,322,924 B2
• Filed: 01/12/2009
• Issued: 04/26/2016
• Est. Priority Date: 12/12/2008
• Status: Active Grant

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Broadcom Corporation (Broadcom, Inc.)
• Inventors: Abraham, Charles
• Primary Examiner(s): Adams, Tashiana
• Assistant Examiner(s): Mull, Fred H
• Application Number:
  US12/352,346
• Publication Number:
  US 20100149033A1
• Time in Patent Office: 2,661 Days
• Field of Search: 342/357.74, 342/357.76, 342/357.62
• US Class Current: 1/1
• CPC Class Codes: G01S 19/34 Power consumption

Abstract

A frequency synthesizer in a GNSS receiver chip enables duty cycling operation of the frequency synthesizer. The frequency synthesizer is cycled on to generate required clock signals for the GNSS receiver chip, and cycled off during a measurement duty cycle comprising measurement available intervals and measurement unavailable intervals. A reference clock inputted to the frequency synthesizer is on during the measurement duty-cycle. During the measurement available intervals, the frequency synthesizer is cycled on to generate the required clock based on the reference clock. During the measurement unavailable intervals, the frequency synthesizer is cycled off and clock timing is maintained based on the reference clock. A number of elapsed clock cycles of the reference clock is captured for a measurement unavailable interval and transferred to a clock offset. The GNSS receiver chip processes signals received using the required clock and the clock offset in a following measurement available interval.

Claims

1. A method for communication, the method comprising:

receiving a first indication that a frequency synthesizer should be on based on a determination that a GNSS receiver chip is in a first measurement available interval of a measurement duty cycle;

cycling the frequency synthesizer on within the GNSS receiver chip to generate required clock signals for the GNSS receiver chip in response to the received first indication, wherein the GNSS receiver chip is configured to receive function requests during the first measurement available interval;

receiving a second indication that the GNSS receiver chip has entered a measurement unavailable interval based on a determination that the first measurement available interval has expired;

cycling the frequency synthesizer off in response to the received second indication, wherein the GNSS receiver chip is configured to receive no function request during the measurement unavailable interval;

generating one or more signals in the GNSS receiver chip to concurrently cycle off the frequency synthesizer and activate a counter in the GNSS receiver chip to capture a number of clock cycles of a reference clock during the off cycle; and

transferring the captured number of clock cycles to a clock offset upon entering a second measurement available interval,

wherein the frequency synthesizer is in a low-power state while cycled off.

2. The method according to claim 1, wherein the measurement duty cycle comprises a plurality of measurement available intervals and a plurality of measurement unavailable intervals.

3. The method according to claim 2, wherein a reference clock signal is received by the frequency synthesizer during the measurement duty cycle.

4. The method according to claim 3, comprising cycling on the frequency synthesizer to generate the required clock signals based on the reference clock during the plurality of measurement available intervals.

5. The method according to claim 4, comprising processing signals received by a wireless receiver using the required clock signal during the plurality of measurement available intervals.

6. The method according to claim 3, comprising cycling off the frequency synthesizer inside the GNSS receiver chip during the plurality of measurement unavailable intervals.

7. The method according to claim 6, comprising maintaining clock timing of the required clock signals based on the reference clock during the plurality of measurement unavailable intervals.

8. The method according to claim 7, comprising enabling capturing a number of elapsed clock cycles of the reference clock for a measurement unavailable interval of the measurement duty cycle concurrently with a start of the measurement unavailable interval of the measurement duty cycle.

9. The method according to claim 8, comprising transferring the captured number of elapsed clock cycles of the reference clock fbr the measurement unavailable interval of the measurement duty cycle to a clock offset.

10. The method of claim 1, further comprising:

providing a GNSS baseband with the required clock signal generated by the frequency synthesizer and the clock offset during the second measurement available interval.

11. The method of claim 10, further comprising processing signals received for GNSS measurement during the second measurement available interval using the required clock signal generated by the frequency synthesizer, wherein the frequency synthesizer has clock timing provided by a clock timing control circuit comprising the clock offset.

12. A system for communication, comprising:

one or more circuits in a GNSS receiver chip, the one or more circuits comprising a counter and a frequency synthesizer;

the one or more circuits being configured to;

receive a first indication that a frequency synthesizer should be on based on a determination that a GNSS receiver chip is in a first measurement available interval of a measurement duty cycle;

cycle the frequency synthesizer on to generate required clock signals for at least the GNSS receiver chip in response to the received first indication, wherein the GNSS receiver chip is configured to receive function requests during the first measurement available interval;

receive a second indication that the GNSS receiver chip has entered a measurement unavailable interval based on a determination that the first measurement available interval has expired;

cycle the frequency synthesizer off in response to the received second indication, wherein the GNSS receiver chip is configured to receive no function request during the measurement unavailable interval;

generate one or more signals to concurrently cycle off the frequency synthesizer and activate the counter to capture a number of clock cycles of a reference clock during the off cycle; and

transfer the captured number of clock cycles to a clock offset upon entering a second measurement available interval,

wherein the frequency synthesizer is in a tow-power state while cycled off.

13. The system according to claim 12, wherein the measurement duty cycle comprises a plurality of measurement available intervals and a plurality of measurement unavailable intervals.

14. The system according to claim 13, wherein a reference clock inputted to the frequency synthesizer is on during an entire measurement duty cycle.

15. The system according to claim 14, wherein the one or more circuits are configured to cycle on the frequency synthesizer inside a wireless receiver to generate the required clock signals based on the reference clock during the plurality of measurement available intervals.

16. The system according to claim 15, wherein the one or more circuits are configured to process signals received by the wireless receiver using the required clock during the plurality of measurement available intervals.

17. The system according to claim 14, wherein the one or more circuits are configured to cycle off the frequency synthesizer inside the GNSS receiver chip during the plurality of measurement unavailable intervals.

18. The system according to claim 17, wherein the one or more circuits are configured to maintain clock timing of the required clock signals based on the reference clock during the plurality of measurement unavailable intervals.

19. The system according to claim 18, wherein the one or more circuits are configured to enable capture of a number of elapsed clock cycles of the reference clock for a measurement unavailable interval of the measurement duty cycle concurrently with a start of the measurement unavailable interval of the measurement duty cycle.

20. The system according to claim 19, wherein the one or more circuits are configured to transfer the captured number of elapsed clock cycles of the reference clock for the measurement unavailable interval of the measurement duty cycle to a clock offset.

21. The system according to claim 20, wherein

the one or more circuits are configured to cycle on the frequency synthesizer to generate the required clock signals in a measurement available interval immediately following the measurement unavailable interval of the measurement duty cycle;

and

the one or more circuits are configured to process signals received by the GNSS receiver chip using the required clock signals with the clock offset.

22. A system for communication, comprising:

a GNSS receiver chip comprising a frequency synthesizer and a timing controller with a counter;

wherein the timing controller is configured to provide an indication of whether the frequency synthesizer is to be on or off based on an operation status of the GNSS receiver within a measurement duty cycle;

wherein the GNSS receiver chip is configured to cycle the operation of the frequency synthesizer on to generate clock signals for GNSS measurements when the indication is that the GNSS receiver is in a first measurement available interval of a measurement duty cycle, wherein the GNSS receiver chip is configured to receive a function request during the first measurement available interval;

wherein the GNSS receiver chip is configured to cycle the operation of the frequency synthesizer off when the indication is that the GNSS receiver is in a measurement unavailable interval of a measurement duty cycle, wherein the GNSS receiver chip is configured to receive no function requests during the measurement unavailable interval;

wherein the GNSS receiver chip is configured to generate one or more signals to concurrently turn off the frequency synthesizer and activate the counter to capture a number of clock cycles of a reference clock during the off cycle; and

wherein the GNSS receiver chip is configured to transfer the captured number of dock cycles to a clock offset upon entering a second measurement available interval,

wherein the frequency synthesizer is in a low-power state while cycled off.