Crystal reference clock and radio localization receiver

• US 7,728,684 B2
• Filed: 09/10/2007
• Issued: 06/01/2010
• Est. Priority Date: 09/11/2006
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Tozer, Andrew
• Primary Examiner(s): Kinkead; Arnold
• Assistant Examiner(s): Tan; Richard
• Application Number:
  US11/898,185
• Publication Number:
  US 20080174374A1
• Time in Patent Office: 995 Days
• Field of Search: 331/18, 331/34, 331/37, 331/38, 331/39, 331/40, 331/41, 331/44, 331/46, 331/66, 331/73, 331/158, 331/175, 331/176, 331/177.R, 342/352, 342/357
• US Class Current: 331/176
• CPC Class Codes: H03L 1/026 by using a memory for digitally storing correction values H03L1/025 takes precedence
• CPC Class Codes: H03L 2207/50 All digital phase-locked loop
• CPC Class Codes: H03L 7/0992 comprising a counter or a frequency divider

Abstract

Device and method for temperature compensation in a clock oscillator using quartz crystals, which integrates dual crystal oscillators. The minimal power consumption is achieved through an efficient use of a processor in charge of the synchronization of the two oscillators. The invention is particularly adapted for the provision of a precise reference clock in portable radiolocalization devices.

Claims

1. An apparatus comprising:

a reference oscillator to generate a reference oscillator signal;

a temperature sensitive oscillator thermally coupled to the reference oscillator and to generate a temperature sensitive oscillator signal;

a numerically controlled oscillator to receive the reference oscillator signal and generate a clock signal based, at least in part on the reference oscillator signal and an increment value signal;

a circuit to receive the temperature sensitive oscillator signal, and to generate a control signal based, at least in part, on the temperature sensitive oscillator signal and the clock signal, wherein the control signal comprises information relating to a temperature deviation of the reference oscillator;

memory to store data indicating a function for determining a deviation of a frequency of the reference oscillator signal; and

a processor, connected to the memory, to receive the control signal and the reference oscillator signal, access the data in the memory, calculate a set of interpolated values based, at least in part, on the data using piecewise linear interpolation for an anticipated range of temperature deviation of the reference osciliator generate the increment value signal based, at least in part, on one value of the set of interpolated values and provide the increment value signal to the numerically controlled oscillator.

2. The apparatus of claim 1, wherein the function for determining a deviation of the reference oscillator signal comprises a fifth order polynomial.

3. The apparatus of claim 1, wherein the memory is user-writable.

4. The apparatus of claim 1, further comprising a radio localization receiver configured to receive the clock signal generated by the numerically controlled oscillator.

5. The apparatus of claim 4, wherein the radio localization receiver comprises a GPS core.

6. The apparatus of claim 1, wherein the control signal represents a count of the temperature sensitive oscillator signal during a time interval associated with the clock signal, and wherein the processor derives a beat frequency associated with a comparison of the reference oscillator signal and the temperature sensitive oscillator signal based, at least in part, on the count.

7. A method comprising:

generating a reference oscillator signal with a reference oscillator;

generating a temperature sensitive oscillator signal with a temperature sensitive oscillator thermally coupled to the reference oscillator;

generating a clock signal with a numerically controlled oscillator based, at least in cart on the reference and an increment value signal;

generating a control signal with a circuit based, at least in part, on the temperature sensitive oscillatar signal and the clock signal, wherein the control signal comprises information relating to a temperature deviation of the reference oscillator; and

with a processor;

obtaining data, indicating a function for determining a deviation of the reference oscillator signal, from a memory,

calculating a set of interpolated values based, at least in part, on the data using piecewise linear interpolation for an anticipated range of temperature deviation of the reference oscillator, and

generating the increment value signal based, at least in part, on one value of the set of interpolated values.

8. The method of claim 7, wherein the function for determining a deviation of the reference oscillator signal comprises a fifth order polynomial.

9. The method of claim 7, wherein the memory is user-writable.

10. The method of claim 7, further comprising providing the clock signal to a radio localization receiver.

11. The method of claim 10, wherein the radio localization receiver comprises a GPS core.

12. The method of claim 7, wherein the control signal represents a count of the temperature sensitive oscillator signal during a time interval associated with the clock signal, and further comprising, with the processor, deriving a beat frequency associated with a comparison of the reference oscillator signal and the temperature sensitive oscillator signal based, at least in part, on the count.

13. An article comprising;

a computer readable medium having computer implementable instructions stored thereon that are executable by one or more processors in a device to;

obtain a reference oscillator signal generated by a reference oscillator, wherein the reference oscillator is thermally coupled to a temperature sensitive oscillator that generates a temperature sensitive oscillator signal;

obtain a control signal generated by a circuit based, at least in part, on the temperature sensitive oscillator signal and a clock signal, wherein the control signal comprises information relating to a temperature deviation of the reference oscillator, and wherein the clock signal is generated by a numerically controlled oscillator based, at least in part on the reference oscillator signal and an increment value signal;

obtain data, indicating a function for determining a deviation of the reference oscillator signal, from a memory;

determine a set of interpolated values based, at least in part, on the data using piecewise linear interpolation for an anticipated range of temperature deviation of the reference oscillator;

generate the increment value signal based, at least in part, on one value of the set of interpolated values; and

provide the increment value signal to the numerically controlled oscillator.

14. The article of claim 13 wherein the control signal represents a count of the temperature sensitive oscillator signal during a time interval associated with the clock signal, and wherein the computer implementable instructions are executable by the one or more processors to derive a beat frequency associated with a comparison of the reference oscillator signal and the temperature sensitive oscillator signal based, at least in part, on the count.