Method and system for sharing a clock reference signal within an integrated mobile device

• US 8,559,969 B2
• Filed: 09/15/2008
• Issued: 10/15/2013
• Est. Priority Date: 09/15/2008
• Status: Expired due to Fees

• Current Assignee: Intel Corporation
• Original Assignee: Intel Mobile Communications GmbH (Intel Corporation)
• Inventors: Hammes, Markus, van Waasen, Stefan
• Primary Examiner(s): Wendell, Andrew
• Assistant Examiner(s): TRANDAI, CINDY HUYEN
• Application Number:
  US12/210,763
• Publication Number:
  US 20100069085A1
• Time in Patent Office: 1,856 Days
• Field of Search: 455/556.1, 455/556.2, 455/557, 455/570, 455/114.2, 455/123, 455/125, 455/136, 455/137, 455/164.1, 455/164.2, 455255-260, 455/265, 455/264, 342/457.51, 342/357.27, 342/357.57, 342/357.31, 342/357.68
• US Class Current: 455/456.1
• CPC Class Codes: G01S 19/235 Calibration of receiver components
• CPC Class Codes: H03J 1/0008 using a central processing unit, e.g. a microprocessor digital tuning in general H03J5/0245
• CPC Class Codes: H03J 2200/11 Cellular receiver, e.g. GSM, combined with a GPS receiver
• CPC Class Codes: H03J 7/04 where the frequency control is accomplished by varying the electrical characteristics of a non-mechanically adjustable element or where the nature of the frequency controlling element is not significant
• CPC Class Codes: H04B 15/04 the interference being caused by substantially sinusoidal oscillations, e.g. in a receiver or in a tape-recorder

Abstract

A method and system of a GPS system controlling a voltage of an input signal to an oscillator, the oscillator producing a clock reference signal to the GPS system and a modem system, such that a frequency of the clock reference signal is altered to synchronize the modem system with a corresponding network while the GPS system remains in a locked state.

Claims

1. A method of sharing a clock reference signal of an oscillator that is input to a global positioning system (GPS) and a modem system within an integrated mobile device, the method comprising:

receiving an input signal at the modem system;

comparing the input signal with the clock reference signal at the modem system to define a frequency error signal;

altering a signal input at the oscillator by the GPS based upon the frequency error signal from the modem system to alter a frequency of the clock reference signal to synchronize the modem system with a corresponding network; and

altering a value to be added to the altered frequency clock reference signal that is employed by the GPS, wherein the value is based on the frequency error signal.

2. A method as recited in claim 1, further comprising communicating the frequency error signal to the GPS from the modem system.

3. A method as recited in claim 1, wherein the corresponding network is selected from a group of networks comprising 2G, 3G, 4G, WiMax, or long term evolution (LTE).

4. A method as recited in claim 1, further comprising measuring the frequency of the clock reference signal prior to and subsequent to altering the voltage of the signal input at the oscillator to define a difference and correlating a value of the frequency error signal to the difference.

5. A method as recited in claim 1, wherein the locked state of the GPS has a tolerance in a range of 10 ppb to 100 ppb.

6. A system comprising:

an oscillator to generate a clock reference signal;

a modem system comprising;

a radio frequency (RF) processor to receive the clock reference signal;

an antenna to receive an input signal; and

a digital signal processor (DSP) configured to compare the input signal received by the antenna with the clock reference signal to define a frequency error signal; and

a global positioning system (GPS) comprising;

a GPS radio frequency (RF) processor to receive the clock reference signal;

a frequency compensation unit to receive the frequency error signal and alter a signal input to the oscillator based upon the frequency error signal from the modem system to alter a frequency of the clock reference signal to synchronize the modem system with a corresponding network; and

a carrier numerically controlled oscillator in communication with the frequency compensation unit to add a value to the altered frequency clock reference signal that is employed by the GPS, wherein the value is based on the frequency error signal.

7. A system as recited in claim 6, wherein the oscillator is a temperature-compensated voltage controlled crystal oscillator.

8. A system as recited in claim 6, wherein the oscillator is a digital controlled crystal oscillator.

9. A system as recited in claim 6, wherein the modem system further comprises an automatic frequency control (AFC) unit to produce a digital value that represent a magnitude of the frequency error signal.

10. A system as recited in claim 6, wherein the GPS further comprises a digital to analog converter (DAC) to convert a digital output of the frequency compensation unit to an analog signal to input to the oscillator.

11. A system as recited in claim 10, wherein the GPS RF processor comprises the DAC.

12. A system as recited in claim 6, wherein the GPS further comprises an antenna to receive an additional input signal.

13. A method of sharing a clock reference signal of an oscillator that is input to a global positioning system (GPS) and a modem system, both within an integrated mobile device, the method comprising:

receiving an input signal by the modem system;

comparing the input signal with the clock reference signal by the modem system, defining a frequency error signal;

converting the frequency error signal to a digital value;

communicating the frequency error signal to the GPS;

altering a signal input to the oscillator by the GPS via a digital to analog convertor (DAC) based upon the frequency error signal from the modem system to alter a frequency of the clock reference signal to synchronize the modem system with a corresponding network;

converting the clock reference signal to a digital value; and

adding a value to the altered frequency clock reference signal that is employed by the GPS, wherein the value is based on the frequency error signal.

14. A method as recited in claim 13, wherein synchronizing the modem system further comprises the corresponding network being selected from a group of networks comprising 2G, 3G, 4G, WiMax, or long term evolution (LTE).

15. A method as recited in claim 13, further comprising measuring the frequency of the clock reference signal prior to and subsequent to altering the voltage of the signal input to the oscillator to define a difference and correlating a value of the frequency error signal to the difference.

16. A mobile device comprising:

a modem system comprising a digital signal processor (DSP) configured to compare an input signal received by the modem system with a clock reference signal generated by a single oscillator to define a frequency error signal; and

a global positioning system (GPS) comprising a frequency compensation unit to receive the frequency error signal and alter a signal input to the single oscillator based upon the frequency error signal from the modem system to alter a frequency of the clock reference signal to synchronize the modem system with a corresponding network, the single oscillator being shared between the modem system and the GPS and being controlled by the GPS, and wherein the GPS is configured to alter a value to be added to the altered frequency clock reference signal that is employed by the GPS, wherein the value is based on the frequency error signal.

17. A system as recited in claim 16, wherein the GPS comprises a carrier numerically controlled oscillator in communication with the frequency compensation unit to add a value stored therein with the clock reference signal such that the GPS remains in a locked state.

18. A system as recited in claim 16, wherein the modem system further comprises an automatic frequency control (AFC) unit to produce a digital value that represents a magnitude of the frequency error signal.

19. A system as recited in claim 16, wherein the GPS further comprises a digital to analog converter (DAC) to convert a digital output of the frequency compensation unit to an analog signal to input to the single oscillator.