Frequency and/or phase compensated microelectromechanical oscillator

• US 20050151592A1
• Filed: 01/09/2004
• Published: 07/14/2005
• Est. Priority Date: 01/09/2004
• Status: Active Grant

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Partridge, Aaron, Lutz, Markus
• Granted Patent: US 6,995,622 B2
• Time in Patent Office: Days
• US Class Current: 331/16
• 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: 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
• CPC Class Codes: H03L 1/026 by using a memory for digitally storing correction values H03L1/025 takes precedence
• CPC Class Codes: H03L 1/027 by using frequency conversion means which is variable with temperature, e.g. mixer, frequency divider, pulse add/substract logic circuit H03L1/023, H03L1/026 take precedence
• CPC Class Codes: H03L 1/04 Constructional details for maintaining temperature constant
• CPC Class Codes: H03L 7/07 using several loops, e.g. for redundant clock signal generation
• CPC Class Codes: H03L 7/08 Details of the phase-locked loop
• CPC Class Codes: H03L 7/1974 for fractional frequency division

Abstract

There are many inventions described and illustrated herein. In one aspect, the present invention is directed to a compensated microelectromechanical oscillator, having a microelectromechanical resonator that generates an output signal and frequency adjustment circuitry, coupled to the microelectromechanical resonator to receive the output signal of the microelectromechanical resonator and, in response to a set of values, to generate an output signal having second frequency. In one embodiment, the values may be determined using the frequency of the output signal of the microelectromechanical resonator, which depends on the operating temperature of the microelectromechanical resonator and/or manufacturing variations of the microelectromechanical resonator. In one embodiment, the frequency adjustment circuitry may include frequency multiplier circuitry, for example, PLLs, DLLs, digital/frequency synthesizers and/or FLLs, as well as any combinations and permutations thereof. The frequency adjustment circuitry, in addition or in lieu thereof, may include frequency divider circuitry, for example, DLLS, digital/frequency synthesizers (for example, DDS) and/or FLLs, as well as any combinations and permutations thereof.

Claims

1. A compensated microelectromechanical oscillator, comprising:

a microelectromechanical resonator to generate an output signal wherein the output signal includes a first frequency;

frequency adjustment circuitry, coupled to the microelectromechanical resonator to receive the output signal of the microelectromechanical resonator and, in response to a set of values, to generate an output signal having second frequency using the output signal of the microelectromechanical resonator; and

wherein the values are determined using the first frequency which depends on the operating temperature of the microelectromechanical resonator.

2. The microelectromechanical oscillator of claim 1 wherein the microelectromechanical resonator is uncompensated and wherein the values are dynamically determined based on an estimation of the temperature of the microelectromechanical resonator.

3. The microelectromechanical oscillator of claim 1 wherein the values are determined using empirical data.

4. The microelectromechanical oscillator of claim 1 wherein the values are determined using mathematical modeling.

5. The microelectromechanical oscillator of claim 2 wherein the values are determined using data which is representative of the operating temperature of the microelectromechanical resonator.

6. The microelectromechanical oscillator of claim 1 wherein the frequency adjustment circuitry includes frequency multiplier circuitry and wherein the second frequency is greater than the first frequency.

7. The microelectromechanical oscillator of claim 6 wherein the frequency multiplier circuitry is a fractional-N PLL or digital/frequency synthesizer.

8. The microelectromechanical oscillator of claim 1 wherein the frequency adjustment circuitry includes:

frequency multiplier circuitry to generate an output signal having frequency using a first set of values, wherein the frequency of the output signal is greater than the first frequency; and

frequency divider circuitry, coupled to the frequency multiplier circuitry, to receive the output signal of the frequency multiplier circuitry and, based on a second set of values, to generate the output signal having the second frequency.

9. The microelectromechanical oscillator of claim 8 wherein the frequency multiplier circuitry is a fractional-N PLL.

10. The microelectromechanical oscillator of claim 8 wherein the frequency divider circuitry is an integer-N PLL or a DLL.

11. The microelectromechanical oscillator of claim 8 wherein the frequency multiplier circuitry is a digital/frequency synthesizer.

12. The microelectromechanical oscillator of claim 11 wherein the digital/frequency synthesizer is a DDS.

13. The microelectromechanical oscillator of claim 1 wherein the frequency adjustment circuitry includes:

first frequency multiplier circuitry to generate an output signal having frequency using a first set of values and the output signal of the microelectromechanical resonator, wherein the frequency of the output signal is greater than the first frequency; and

second frequency multiplier circuitry, coupled to the first frequency multiplier circuitry, to receive the output signal of the first frequency multiplier circuitry and, based on a second set of values, to generate the output signal having the second frequency wherein the second frequency is greater than the frequency of the output signal of the first frequency multiplier circuitry.

14. The microelectromechanical oscillator of claim 13 wherein the first frequency multiplier circuitry is a fractional-N PLL.

15. The microelectromechanical oscillator of claim 14 wherein the second frequency multiplier circuitry is an integer-N PLL or a digital/frequency synthesizer.

16. The microelectromechanical oscillator of claim 13 wherein the first frequency multiplier circuitry is a digital/frequency synthesizer.

17. A compensated microelectromechanical oscillator, comprising:

a microelectromechanical resonator to generate an output signal wherein the output signal includes a frequency;

frequency adjustment circuitry, coupled to the microelectromechanical resonator to receive the output signal of the microelectromechanical resonator and, in response to a set of values, to generate an output signal having an output frequency; and

wherein the set of values is determined based on the frequency of the output signal of the microelectromechanical resonator and data which is representative of the operating temperature of the microelectromechanical resonator.

18. The microelectromechanical oscillator of claim 17 wherein the microelectromechanical resonator is uncompensated.

19. The microelectromechanical oscillator of claim 17 wherein the frequency adjustment circuitry includes frequency multiplier circuitry wherein the second frequency is greater than the frequency of the microelectromechanical resonator.

20. The microelectromechanical oscillator of claim 19 wherein the frequency multiplier circuitry is a fractional-N PLL or digital/frequency synthesizer.

21. The microelectromechanical oscillator of claim 17 wherein the frequency adjustment circuitry includes frequency divider circuitry wherein the output frequency is less than the frequency of the microelectromechanical resonator.

22. The microelectromechanical oscillator of claim 21 wherein the frequency divider circuitry is a fractional-N PLL, digital/frequency synthesizer or DLL.

23. The microelectromechanical oscillator of claim 17 wherein the values are dynamically provided to the frequency adjustment circuitry.

24. The microelectromechanical oscillator of claim 23 wherein the values are determined using an estimated frequency of the output signal of the microelectromechanical resonator and wherein the estimated frequency is determined using empirical data.

25. The microelectromechanical oscillator of claim 23 wherein the values are determined using an estimated frequency of the output signal of the microelectromechanical resonator and wherein the estimated frequency is determined using mathematical modeling.

26. The microelectromechanical oscillator of claim 17 wherein the frequency adjustment circuitry includes:

frequency multiplier circuitry to generate an output signal having frequency using a first set of values and the output signal of the microelectromechanical resonator, wherein the frequency of the output signal is greater than the frequency of the microelectromechanical resonator;

frequency divider circuitry, coupled to the frequency multiplier circuitry, to receive the output signal of the frequency multiplier circuitry and, based on a second set of values, to generate the output signal having the output frequency; and

wherein the set of values includes the first set of values and the second set of values.

27. The microelectromechanical oscillator of claim 26 wherein the frequency multiplier circuitry is a fractional-N PLL.

28. The microelectromechanical oscillator of claim 26 wherein the frequency divider circuitry is an integer-N PLL or a DLL.

29. The microelectromechanical oscillator of claim 26 wherein the frequency multiplier circuitry is a digital/frequency synthesizer.

30. The microelectromechanical oscillator of claim 29 wherein the frequency divider circuitry is a DLL.

31. The microelectromechanical oscillator of claim 17 wherein the frequency adjustment circuitry includes:

first frequency multiplier circuitry to generate an output signal having frequency using a first set of values and the output signal of the microelectromechanical resonator, wherein the frequency of the output signal is greater than the frequency of the microelectromechanical resonator;

second frequency multiplier circuitry, coupled to the first frequency multiplier circuitry, to receive the output signal of the first frequency multiplier circuitry and, based on a second set of values, to generate the output signal, wherein the frequency of the output signal is greater than the frequency of the output signal of the first frequency multiplier circuitry; and

wherein the set of values includes the first set of values and the second set of values.

32. The microelectromechanical oscillator of claim 31 wherein:

the first frequency multiplier circuitry is a fractional-N PLL; and

the second frequency multiplier circuitry is an integer-N PLL or a digital/frequency synthesizer.

33. The microelectromechanical oscillator of claim 31 wherein:

the first frequency multiplier circuitry is a digital/frequency synthesizer; and

the second frequency multiplier circuitry is an integer-N PLL or a digital/frequency synthesizer.

34. A compensated microelectromechanical oscillator, comprising:

a microelectromechanical resonator to generate an output signal wherein the output signal includes a first frequency;

frequency adjustment circuitry, coupled to the microelectromechanical resonator to receive the output signal of the microelectromechanical resonator and, in response to a set of values, to generate an output signal having a second frequency using the output signal of the microelectromechanical resonator; and

wherein the values are determined using the first frequency which depends on manufacturing variations of the microelectromechanical resonator.

35. The microelectromechanical oscillator of claim 34 wherein the values are dynamically determined based on an estimation of the operating temperature of the microelectromechanical resonator.

36. The microelectromechanical oscillator of claim 35 wherein the microelectromechanical resonator is uncompensated.

37. The microelectromechanical oscillator of claim 34 wherein the values are determined using empirical data.

38. The microelectromechanical oscillator of claim 34 wherein the values are determined using mathematical modeling.

39. The microelectromechanical oscillator of claim 34 wherein the frequency adjustment circuitry includes frequency multiplier circuitry to generate the output signal having the second frequency using the set of values and the output signal of the micromechanical resonator, and wherein the second frequency is greater than the first frequency.

40. The microelectromechanical oscillator of claim 39 wherein the frequency multiplier circuitry is a fractional-N PLL or digital/frequency synthesizer.

41. The microelectromechanical oscillator of claim 34 wherein the frequency adjustment circuitry includes frequency divider circuitry to generate the output signal having the second frequency using the set of values and the output signal of the micromechanical resonator, and wherein the second frequency is less than the first frequency.

42. The microelectromechanical oscillator of claim 41 wherein the frequency divider circuitry is a PLL, digital/frequency synthesizer or DLL.

43. The microelectromechanical oscillator of claim 34 wherein the frequency adjustment circuitry includes:

first frequency multiplier circuitry to generate an output signal having frequency using a first set of values and the output signal of the microelectromechanical resonator, wherein the frequency of the output signal is greater than the first frequency;

second frequency multiplier circuitry, coupled to the first frequency multiplier circuitry, to receive the output signal of the first frequency multiplier circuitry and, based on a second set of values, to generate the output signal having the second frequency wherein the second frequency is greater than the frequency of the output signal of the first frequency multiplier circuitry; and

wherein the set of values includes the first and second sets of values.

44. The microelectromechanical oscillator of claim 43 wherein the first frequency multiplier circuitry is a fractional-N PLL.

45. The microelectromechanical oscillator of claim 44 wherein the second frequency multiplier circuitry is an integer-N PLL or a digital/frequency synthesizer.

46. The microelectromechanical oscillator of claim 43 wherein the first frequency multiplier circuitry is a digital/frequency synthesizer.

47. The microelectromechanical oscillator of claim 46 wherein the second frequency multiplier circuitry is an integer-N PLL or a digital/frequency synthesizer.

48. A method of programming a temperature compensated microelectromechanical oscillator having a microelectromechanical resonator to generate an output signal wherein the output signal includes a first frequency, frequency adjustment circuitry, coupled to the resonator to receive the output signal of the microelectromechanical resonator and to provide an output signal having a frequency that is within a predetermined range of frequencies, the method comprising:

measuring the first frequency of the output signal of the microelectromechanical resonator when the microelectromechanical resonator is at a first operating temperature;

calculating a first set of values; and

providing the first set of values to the frequency adjustment circuitry.

49. The method of claim 48 further including calculating a second set of values wherein the frequency adjustment circuitry, in response to the second set of values, provides the output signal having the frequency that is within a predetermined range of frequencies when the microelectromechanical resonator is at a second operating temperature.

50. The method of claim 49 wherein calculating the second set of values includes using empirical data.

51. The method of claim 49 wherein calculating the second set of values includes using mathematical modeling.

52. The method of claim 49 wherein the temperature compensated microelectromechanical oscillator further includes a memory and wherein the method further includes storing the second set of values in a memory.

53. A method of operating a temperature compensated microelectromechanical oscillator having a microelectromechanical resonator to generate an output signal wherein the output signal includes a first frequency, and frequency adjustment circuitry, coupled to the resonator to receive the output signal of the microelectromechanical resonator wherein, in response to a first set of values, the frequency adjustment circuitry provides an output signal having a second frequency wherein the second frequency is within a predetermined range of frequencies, the method comprising:

acquiring data which is representative of the temperature of the microelectromechanical resonator;

determining that the microelectromechanical resonator is at a second operating temperature;

determining a second set of values wherein the frequency adjustment circuitry, in response to the second set of values, provides the output signal having the frequency that is within a predetermined range of frequencies when the microelectromechanical resonator is at the second operating temperature; and

providing the second set of values to the frequency adjustment circuitry.

54. The method of claim 53 further including storing the second set of values is stored in a memory of the compensated microelectromechanical oscillator.

55. The method of claim 53 further including:

measuring the temperature of the microelectromechanical resonator; and

calculating the operating temperature of the microelectromechanical resonator.

56. The method of claim 53 wherein the second set of values is determined using empirical data.

57. The method of claim 53 wherein the second set of values is determined using mathematical modeling.

58. The method of claim 53 wherein the frequency adjustment circuitry includes:

first frequency multiplier circuitry to generate an output signal having frequency using a first subset of values wherein the frequency of the output signal is greater than the first frequency;

second frequency multiplier circuitry, coupled to the first frequency multiplier circuitry, to receive the output signal of the first frequency multiplier circuitry and, based on a second subset of values, to generate the output signal having the second frequency wherein the second frequency is greater than the frequency of the output signal of the first frequency multiplier circuitry; and

wherein the second set of values includes the first and second subsets of values, and

the method further comprises determining the first subset of values wherein the frequency adjustment circuitry, in response to the first subset of values, provides the output signal having the frequency that is within a predetermined range of frequencies when the microelectromechanical resonator is at the second operating temperature.

59. The method of claim 58 wherein the first frequency multiplier circuitry is a fractional-N PLL.

60. The method of claim 59 wherein the second frequency multiplier circuitry is an integer-N PLL or a digital/frequency synthesizer.

61. The method of claim 58 wherein the first frequency multiplier circuitry is a digitai/frequency synthesizer.

62. The method of claim 61 wherein the second frequency multiplier circuitry is an integer-N PLL or a digital/frequency synthesizer.

63. The method of claim 58 further including using the same second subset of values when the microelectromechanical resonator is at the second operating temperature.