Wireless communications system including dual-purpose clock reference for global positioning system and baseband

• US 9,214,923 B2
• Filed: 05/06/2015
• Issued: 12/15/2015
• Est. Priority Date: 06/24/2009
• Status: Active Grant

• Current Assignee: Marvell Asia Pte Limited (Marvell Technology Group Limited)
• Original Assignee: Marvell World Trade Limited (Marvell Technology Group Limited)
• Inventors: Uehara, Gregory, Zaslavsky, Alexander, Brunn, Brian T.
• Primary Examiner(s): Tran, Tuan A
• Application Number:
  US14/705,320
• Publication Number:
  US 20150236672A1
• Time in Patent Office: 223 Days
• Field of Search: 455255-265, 4551921-1923, 342 98-103, 342/199, 342/357.62, 342/357.64, 342/357.75, 331/18, 331/34, 331/60
• US Class Current: 1/1
• CPC Class Codes: G01S 19/23 Testing, monitoring, correcting or calibrating of receiver elements
• CPC Class Codes: H03J 1/005 in a loop
• CPC Class Codes: H03J 7/02 Automatic frequency control H03J7/18 takes precedence
• 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: H03L 7/0805 the loop being adapted to provide an additional control signal for use outside the loop
• CPC Class Codes: H03L 7/197 a time difference being used for locking the loop, the counter counting between numbers which are variable in time or the frequency divider dividing by a factor variable in time, e.g. for obtaining fractional frequency division H03L7/1806 takes precedence
• CPC Class Codes: H03L 7/22 using more than one loop
• CPC Class Codes: H04B 1/16 Circuits
• CPC Class Codes: H04B 1/3805 with built-in auxiliary receivers
• CPC Class Codes: H04W 84/12 WLAN [Wireless Local Area Networks]

Abstract

A wireless communications system includes a clock module, a global positioning system (GPS) module, an integrated circuit for a cellular transceiver, and a baseband module. The clock module is configured to generate a first clock reference that is not corrected using automatic frequency correction (AFC). The GPS module is configured to operate in response to the first clock reference. The integrated circuit includes a system phase lock loop (PLL) configured to (i) operate in response to the first clock reference, and (ii) generate a corrected clock reference by performing AFC on the first clock reference in response to an AFC signal. The baseband module is configured to (i) operate in response to the first clock reference from the clock module, and (ii) generate the AFC signal.

Claims

1. A wireless communications system comprising:

a clock module configured to generate a first clock reference that is not corrected using automatic frequency correction (AFC);

a global positioning system (GPS) module configured to operate in response to the first clock reference;

an integrated circuit for a cellular transceiver, wherein the integrated circuit comprises a system phase lock loop (PLL) configured to (i) operate in response to the first clock reference, and (ii) generate a corrected clock reference by performing AFC on the first clock reference in response to an AFC signal; and

a baseband module configured to (i) operate in response to the first clock reference from the clock module, and (ii) generate the AFC signal.

2. The wireless communications system of claim 1, wherein the clock module comprises a temperature-compensated crystal oscillator.

3. The wireless communications system of claim 1, further comprising a buffer configured to (i) generate a controlled clock reference by controlling a slew rate of the first clock reference, and (ii) output the controlled clock reference to the GPS module.

4. The wireless communications system of claim 3, wherein the buffer is configured to control the slew rate of the first clock reference according to a slew rate adjustment signal.

5. The wireless communications system of claim 1, further comprising a wireless local area network (WLAN) module configured to operate in response to the first clock reference.

6. The wireless communications system of claim 1, further comprising a Bluetooth module configured to operate in response to the first clock reference.

7. The wireless communications system of claim 1 wherein the integrated circuit further comprises a receiver module configured to (i) receive radio frequency signals from a wireless medium, and (ii) in response to the corrected clock reference, generate baseband signals based on the received radio frequency signals.

8. The wireless communications system of claim 7 wherein the baseband module is configured to (i) receive the baseband signals, and (ii) in response to the first clock reference, generate the AFC signal based on the baseband signals.

9. The wireless communications system of claim 8 wherein:

the integrated circuit further comprises a selection module configured to output a selected clock reference based alternatively on the first clock reference and the corrected clock reference; and

the baseband module is configured to operate in response to the selected clock reference from the selection module.

10. The wireless communications system of claim 1 wherein:

the integrated circuit further comprises a selection module configured to output a selected clock reference based alternatively on the first clock reference and the corrected clock reference; and

the baseband module is configured to operate in response to the selected clock reference from the selection module.

11. A method of operating a wireless communications system, the method comprising:

generating a first clock reference that is not corrected using automatic frequency correction (AFC);

operating a global positioning system (GPS) module in response to the first clock reference;

using a phase lock loop (PLL) integrated circuit, generating a corrected clock reference by performing AFC on the first clock reference in response to an AFC signal; and

using a baseband module, generating the AFC signal in response to the first clock reference.

12. The method of claim 11, wherein the generating the first clock reference is performed using a temperature-compensated crystal oscillator.

13. The method of claim 11, further comprising generating a controlled clock reference by controlling a slew rate of the first clock reference, and providing the controlled clock reference to the GPS module.

14. The method of claim 13, wherein the controlling the slew rate of the first clock reference is performed according to a slew rate adjustment signal.

15. The method of claim 11, further comprising operating a wireless local area network (WLAN) module in response to the first clock reference.

16. The method of claim 11, further comprising operating a Bluetooth module in response to the first clock reference.

17. The method of claim 11, further comprising receiving radio frequency signals from a wireless medium and, in response to the corrected clock reference, generating baseband signals based on the received radio frequency signals.

18. The method of claim 17, further comprising, operating the baseband module in response to the first clock reference to generate the AFC signal based on the baseband signals.

19. The method of claim 18, further comprising generating a selected clock reference based alternatively on the first clock reference and the corrected clock reference, and operating the baseband module in response to the selected clock reference.

20. The method of claim 11, further comprising generating a selected clock reference based alternatively on the first clock reference and the corrected clock reference, and operating the baseband module in response to the selected clock reference.