Microelectromechanical oscillator and method of operating same

• US 7,369,004 B2
• Filed: 07/26/2006
• Issued: 05/06/2008
• Est. Priority Date: 06/14/2006
• Status: Active Grant

• Current Assignee: SiTime Corporation (Megachips Corporation)
• Original Assignee: SiTime Corporation (Megachips Corporation)
• Inventors: Partridge, Aaron, Lutz, Markus, Boser, Bernhard E., Lu, Crist Y., Hagelin, Paul Merritt
• Primary Examiner(s): Pascal; Robert J.
• Assistant Examiner(s): GOODLEY, JAMES E
• Application Number:
  US11/493,704
• Publication Number:
  US 20070290764A1
• Time in Patent Office: 650 Days
• Field of Search: 331/116.M, 331/154, 331/156
• US Class Current: 331/156
• CPC Class Codes: G01K 7/32 using change of resonant frequency of a crystal
• CPC Class Codes: H03B 5/04 Modifications of generator to compensate for variations in physical values, e.g. power supply, load, temperature
• CPC Class Codes: H03B 5/30 with frequency-determining element being electromechanical resonator
• CPC Class Codes: H03H 2009/02527 Combined
• CPC Class Codes: H03H 9/02448 of temperature influence
• CPC Class Codes: H03H 9/2405 of microelectro-mechanical resonators
• CPC Class Codes: H03L 1/022 by indirect stabilisation, i.e. by generating an electrical correction signal which is a function of the temperature H03L1/021 takes precedence

Abstract

There are many inventions described and illustrated herein. In one aspect, the present inventions relate to a temperature measurement system comprising (1) a first microelectromechanical resonator to generate a first output signal having a frequency that varies with operating temperature, wherein the first microelectromechanical resonator includes a frequency function of temperature; (2) a second microelectromechanical resonator to generate a second output signal having a frequency that varies with operating temperature, wherein the second microelectromechanical resonator includes a frequency function of temperature; and (3) frequency division circuitry, coupled to the first and second microelectromechanical resonators, to determine data which is representative of the operating temperature of the first and/or second microelectromechanical resonator using (i) data which is representative of the frequency of the first output signal and (ii) data which is representative of the frequency of the second output signal. The frequency division circuitry may include circuitry to divide the frequency of the first output signal by the frequency of the second output signal (whether in digital or analog domain).

Claims

1. An oscillator system, comprising:

a temperature measurement system including;

a first microelectromechanical resonator to generate a first output signal having a frequency that varies with operating temperature, wherein the first microelectromechanical resonator includes a frequency function of temperature;

a second microelectromechanical resonator to generate a second output signal having a frequency that varies with operating temperature, wherein the second microelectromechanical resonator includes a frequency function of temperature;

frequency division circuitry, coupled to the first and second microelectromechanical resonators, to determine data which is representative of the operating temperature of the first and/or second microelectromechanical resonator using (i) data which is representative of the frequency of the first output signal and (ii) data which is representative of the frequency of the second output signal;

frequency manipulation circuitry, coupled to the first and second microelectromechanical resonators, to generate a third output signal using the first and second output signals; and

clock alignment circuitry, coupled to the temperature measurement system and frequency manipulation circuitry, to generate an output signal having frequency which is substantially stable over a predetermined operating temperature using (i) the third output and (ii) the data which is representative of the operating temperature of the first and/or second microelectromechanical resonator.

2. The oscillator system of claim 1 wherein the frequency manipulation circuitry includes frequency subtraction circuitry.

3. The oscillator system of claim 2 wherein the frequency subtraction circuitry includes digital or analog circuitry.

4. The oscillator system of claim 1 wherein the frequency division circuitry includes circuitry to divide the frequency of the first output signal by the frequency of the second output signal in a digital domain.

5. The oscillator system of claim 4 wherein the frequency division circuitry includes counter circuitry and/or analog-to-digital converter circuitry.

6. The oscillator system of claim 4 wherein the frequency division circuitry further includes:

means for generating the data which is representative of the frequency of the first output signal;

means for generating the data which is representative of the frequency of the second output signal; and

means for dividing the data which is representative of the frequency of the first output signal by the data which is representative of the frequency of the second output signal.

7. The oscillator system of claim 1 wherein the frequency division circuitry includes circuitry to divide the frequency of the first output signal by the frequency of the second output signal in an analog domain.

8. The oscillator system of claim 7 wherein the frequency division circuitry further includes:

means for generating the data which is representative of the frequency of the first output signal;

means for generating the data which is representative of the frequency of the second output signal; and

divider circuitry, coupled to the first and second counter circuitry, to determine the data which is representative of the operating temperature of the first and/or second microelectromechanical resonator using (i) the data which is representative of the frequency of the first output signal and (ii) the data which is representative of the frequency of the second output signal.

9. The oscillator system of claim 4 wherein the clock alignment circuitry generates the output signal having frequency which is substantially stable over a predetermined operating temperature using one or more phase locked loops, delay locked loops, frequency locked loops and/or digital/frequency synthesizers.

10. The oscillator system of claim 4 wherein the clock alignment circuitry generates the output signal having frequency which is substantially stable over a predetermined operating temperature using (i) the third output signal and (ii) one or more phase locked loops, delay locked loops, frequency locked loops and/or digital/frequency synthesizers.

11. The oscillator system of claim 1 wherein the first and the second microelectromechanical resonators are the same physical structure.

12. The oscillator system of claim 1 wherein the first microelectromechancal resonator and the second microelectromechanical resonator include different crystalline orientations, or directions in and/or on the same substrate.

13. An oscillator system, comprising:

a temperature measurement system including;

a first microelectromechanical resonator to generate a first output signal having a frequency that varies with temperature, wherein the first microelectromechanical resonator includes a frequency function of temperature;

a second microelectromechanical resonator to generate a second output signal having a frequency that varies with temperature, wherein the second microelectromechanical resonator includes a frequency function of temperature;

frequency division circuitry, coupled to the first and second microelectromechanical resonators, wherein the frequency division circuitry includes;

circuitry to generate (i) data which is representative of the frequency of the first output signal, and (ii) data which is representative of the frequency of the second output signal; and

analysis circuitry to determine data which is representative of the operating temperature of the first and/or second microelectromechanical resonator by dividing;

(i) the data which is representative of the frequency of the first output signal by the data which is representative of the frequency of the second output signal or (ii) the data which is representative of the frequency of the second output signal by the data which is representative of the frequency of the first output signal;

frequency subtraction circuitry, coupled to the first and second microelectromechanical resonators, to generate a third output signal having frequency which is substantially stable over a predetermined operating temperature using the first and second output signals; and

clock alignment circuitry to generate an output signal using the (i) data which is representative of the operating temperature of the first and/or second microelectromechanical resonator, and (ii) the third output signal.

14. The oscillator system of claim 13 wherein the frequency subtraction circuitry includes frequency mixer circuitry.

15. The oscillator system of claim 13 wherein the output signal of the clock alignment circuitry includes a frequency which is substantially stable over a predetermined operating temperature and wherein the clock alignment circuitry generates the output signal using one or more phase locked loops, delay locked loops, frequency locked loops and/or digital/frequency synthesizers.

16. The oscillator system of claim 13 wherein the clock alignment circuitry further includes processor circuitry, coupled to the frequency division circuitry, to determine the operating temperature of the first and/or second microelectromechanical resonator using the data which is representative of the operating temperature of the first and/or second microelectromechanical resonator.

17. The oscillator system of claim 16 wherein:

(i) the clock alignment circuitry generates the output signal having frequency which is substantially stable over a predetermined operating temperature using one or more phase locked loops, delay locked loops, frequency locked loops and/or digital/frequency synthesizers; and

(ii) the processor circuitry, in response to determining a change in operating temperature, changes one or more coefficients of one or more phase locked loops, delay locked loops, frequency locked loops and/or digital/frequency synthesizers of the clock alignment circuitry.

18. The oscillator system of claim 13 wherein the first and the second microelectromechanical resonators are the same physical structure.

19. The oscillator system of claim 13 wherein the first microelectromechanical resonator and the second microelectromechanical resonator include different crystalline orientations, or directions in and/or on the same substrate.

20. An oscillator system, comprising:

a temperature measurement system including;

a first microelectromechanical resonator to generate a first output signal having a frequency that varies with operating temperature, wherein the first microelectromechanical resonator includes a frequency function of temperature;

a second microelectromechanical resonator to generate a second output signal having a frequency that varies with operating temperature, wherein the second microelectromechanical resonator includes a frequency function of temperature;

frequency division circuitry, coupled to the first and second microelectromechanical resonators, to determine data which is representative of the operating temperature of the first and/or second microelectromechanical resonator using (i) data which is representative of the frequency of the first output signal and (ii) data which is representative of the frequency of the second output signal;

frequency mixer circuitry, coupled to the plurality of microelectromechanical resonators, to generate an output signal having frequency that is substantially stable over an operating temperature using the first and second output signals;

clock alignment circuitry, coupled to the temperature measurement system and the frequency mixer circuitry, to generate an output signal using (i) the data which is representative of the operating temperature of the first and/or second microelectromechanical resonator, and (ii) the third output signal; and

wherein the first and second microelectromechanical resonators are disposed on and/or in the same substrate and the frequency division circuitry, the frequency mixer circuitry and the clock alignment circuitry are disposed on and/or in the same substrate.

21. The oscillator system of claim 20 wherein:

(i) the clock alignment circuitry generates the output signal having frequency which is substantially stable over a predetermined operating temperature using one or more phase locked loops, delay locked loops, frequency locked loops and/or digital/frequency synthesizers;

(ii) the clock alignment circuitry further includes circuitry, coupled to the frequency division circuitry, to determine the operating temperature of the first and/or second microelectromechanical resonator using the data which is representative of the operating temperature of the first and/or second microelectromechanical resonator; and

(iii) the circuitry to determine the operating temperature of the first and/or second microelectromechanical resonator, in response to determining a change in operating temperature, changes one or more coefficients of one or more phase locked loops, delay locked loops, frequency locked loops and/or digital/frequency synthesizers of the clock alignment circuitry.

22. The oscillator system of claim 20 wherein the first and second microelectromechanical resonators, frequency division circuitry, frequency mixer circuitry and clock alignment circuitry are disposed on and/or in the same substrate.

23. The oscillator system of claim 20 wherein the frequency mixer circuitry further includes filter circuitry, coupled to the frequency mixer circuitry, to receive an output of the frequency mixer circuitry and to attenuate a frequency difference component or frequency sum component of the output of the frequency mixer circuitry.

24. The oscillator system of claim 23 wherein the frequency mixer circuitry includes digital or analog circuitry.

25. The oscillator system of claim 20 wherein the frequency division circuitry generates data which is representative of the operating temperature of the first and/or second microelectromechanical resonator by dividing (i) the data which is representative of the frequency of the first output signal by the data which is representative of the frequency of the second output signal or (ii) the data which is representative of the frequency of the second output signal by the data which is representative of the frequency of the first output signal.

26. The oscillator system of claim 20 wherein the frequency division circuitry includes counter circuitry and/or analog-to-digital converter circuitry.

27. The oscillator system of claim 20 wherein the first and second microelectromechanical resonators are the same physical structure.

28. The oscillator system of claim 20 wherein the output signal of the clock alignment circuitry includes a frequency which is substantially stable over a predetermined operating temperature and wherein the clock alignment circuitry generates the output signal using (i) one or more phase locked loops, delay locked loops, frequency locked loops and/or digital/frequency synthesizers and (ii) the first output signal.

29. The oscillator system of claim 28 wherein the one or more digital/frequency synthesizers include one or more direct digital synthesizers, frequency synthesizers, fractional synthesizers and/or numerically controlled oscillators.

30. The oscillator system of claim 28 wherein the one or more phase locked loops, delay locked loops, digital/frequency synthesizer and/or frequency locked loops include fractional and/or fine-fractional type phase locked loops, delay locked loops, digital/frequency synthesizer and/or frequency locked loops.