Frequency and/or phase compensated microelectromechanical oscillator

• US 7,224,236 B2
• Filed: 09/30/2005
• Issued: 05/29/2007
• Est. Priority Date: 01/09/2004
• Status: Active Grant

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Partridge, Aaron, Lutz, Markus
• Primary Examiner(s): MIS, DAVID C
• Application Number:
  US11/239,845
• Publication Number:
  US 20060022764A1
• Time in Patent Office: 606 Days
• Field of Search: 331/18, 331/66, 331/74, 331/75, 331/116.R, 331/116.FE, 331/116.M, 331/154, 331/156, 331/175, 331/176
• US Class Current: 331/66
• 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 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 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, wherein;

(i) the frequency adjustment circuitry includes frequency multiplier circuitry, and

(ii) the second frequency is greater than the first frequency; and

wherein the microelectromechanical resonator and the frequency adjustment circuitry are integrated in or on a common substrate.

2. The microelectromechanical oscillator of claim 1 wherein the set of values is determined, at least in part, using information which is representative of the first frequency.

3. The microelectromechanical oscillator of claim 2 wherein the first frequency depends, at least in part, on an operating temperature of the microelectromechanical resonator.

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

5. The microelectromechanical oscillator of claim 1 wherein the values are determined during (i) testing of the microelectromechanical resonator and/or microelectromechanical oscillator, (ii) calibration of the microelectromechanical oscillator, or (iii) operation of the microelectromechanical oscillator.

6. The microelectromechanical oscillator of claim 1 wherein the frequency multiplier circuitry is a fractional-N PLL or digital/frequency Synthesizer.

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

frequency divider circuitry, coupled to the microelectromechanical resonator, to generate an output signal using (1) a first subset of values and (2) the output signal of the microelectromechanical resonator, wherein the frequency of the output signal of the frequency divider circuitry Is less than the frequency of the output signal of the microelectromechanical resonator;

wherein the first frequency multiplier circuitry is coupled to the frequency divider circuitry and, using (1) a second subset of values and (2) the output signal of the frequency divider circuitry, generates the output signal having the second frequency; and

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

8. The microelectromechanical oscillator of claim 1 wherein:

the first frequency multiplier circuitry generates an output signal using (i) a first subset of values and (ii) the output signal of the microelectromechanical resonator;

the frequency adjustment circuitry further includes frequency divider circuitry, coupled to the frequency multiplier circuitry, to generate the output signal having the second frequency using a second subset of values; and

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

9. The microelectromechanical oscillator of claim 8 wherein the frequency divider circuitry is a PLL, digital/frequency synthesizer or DLL.

10. The microelectromechanical oscillator of claim 9 wherein the frequency multiplier circuitry is a PLL or a digital/frequency synthesizer.

11. The microelectromechanical oscillator of claim 1 wherein:

the first frequency multiplier circuitry generates an output signal, having a frequency, using (1) a first subset of values and (2) the output signal of the microelectromechanical resonator, wherein the frequency of the output signal of the first frequency multiplier circuitry is greater than the first frequency;

the frequency adjustment circuitry further includes second frequency multiplier circuitry, coupled to the first frequency multiplier circuitry, to generate the output signal having the second frequency using (1) a second subset of values and (2) the output signal of the first frequency multiplier circuitry; and

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

12. The microelectromechanical oscillator of claim 11 wherein the first frequency multiplier circuitry or the second multiplier circuitry is a fractional-N PLL or digital/frequency synthesizer.

13. The microelectromechanical oscillator of claim 11 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.

14. The microelectromechanical oscillator of claim 11 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.

15. The microelectromechanical oscillator of claim 1 wherein the first frequency depends, at least in part, on an operating temperature of the microelectromechanical resonator and wherein the microelectromechanical oscillator further includes temperature sensor circuitry, integrated in or on the common substrate, to determine information which is representative of the operating temperature of the microelectromechanical resonator, an operating temperature of the microelectromechanical oscillator or an operating temperature of the frequency adjustment circuitry.

16. The microelectromechanical oscillator of claim 15 wherein the values are determined during (i) calibration of the microelectromechanical oscillator or (ii) operation of the microelectromechanical oscillator.

17. The microelectromechanical oscillator of claim 15 further including temperature sensors, integrated in or on the common substrate, to provide data which is representative of temperature to the temperature sensor circuitry.

18. 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 generate an output signal using the output signal of the microelectromechanical resonator and a set of values, wherein;

(i) the frequency adjustment circuitry includes frequency divider circuitry comprising a PLL, DLL, FLL or digital/frequency synthesizer, and

(ii) the output signal of frequency adjustment circuitry includes a frequency that is less than the frequency of the output signal of the microelectromechanical resonator; and

wherein the microelectromechanical resonator and the frequency adjustment circuitry are integrated in or on a common substrate.

19. The microelectromechanical oscillator of claim 18 wherein the frequency divider circuitry is a PLL which is a fractional-N PLL.

20. The microelectromechanical oscillator of claim 18 wherein the frequency divider circuitry is a DDS.

21. The microelectromechanical oscillator of claim 18 wherein the set of values is determined, at least in part, using information which is representative of the first frequency.

22. The microelectromechanical oscillator of claim 21 wherein the first frequency depends, at least in part, on an operating temperature of the microelectromechanical resonator.

23. The microelectromechanical oscillator of claim 18 wherein the values are determined using empirical data or mathematical modeling.

24. The microelectromechanical oscillator of claim 18 wherein the values are determined during (i) testing of the microelectromechanical resonator and/or microelectromechanical oscillator, (ii) calibration of the microelectromechanical oscillator, or (iii) operation of the microelectromechanical oscillator.

25. The microelectromechanical oscillator of claim 18 wherein the set of 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 or mathematical modeling.

26. The microelectromechanical oscillator of claim 18 wherein the frequency adjustment circuitry further includes:

frequency multiplier circuitry, coupled to receive the output signal of the microelectromechanical resonator, to generate an output signal having a frequency using (1) a first set of values and (2) the output signal of the microelectromechanical resonator, wherein the frequency of the output signal of the frequency multiplier circuitry is greater than the frequency of the output signal of the microelectromechanical resonator; and

wherein the frequency divider circuitry is coupled to the frequency multiplier circuitry and using a second set of values, generates the output signal having the output frequency.

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

28. The microelectromechanical oscillator of claim 26 wherein the frequency divider circuitry is a PLL which is a fractional-N PLL.

29. The microelectromechanical oscillator of claim 26 wherein the frequency multiplier circuitry is a PLL, DLL, FLL, or digital/frequency synthesizer.

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

31. The microelectromechanical oscillator of claim 29 wherein the frequency divider circuitry is a PLL which is a fractional-N PLL.

32. The microelectromechanical oscillator of claim 18 wherein the frequency divider circuitry is coupled to receive the output signal of the microelectromechanical resonator and generate an output signal having a frequency using (1) a first set of values and (2) the output signal of the microelectromechanical resonator;

and

wherein frequency adjustment circuitry further includes frequency multiplier circuitry, coupled to the frequency divider circuitry, and, using a second set of values, to generate the output signal having the output frequency.

33. The microelectromechanical oscillator of claim 32 wherein the frequency divider circuitry is a DDS.

34. The microelectromechanical oscillator of claim 32 wherein the frequency multiplier circuitry is a PLL.

35. The microelectromechanical oscillator of claim 18 wherein the first frequency depends, at least in part, on an operating temperature of the microelectromechanical resonator and wherein the microelectromechanical oscillator further includes temperature sensor circuitry, integrated in or on the common substrate, to determine information which is representative of the operating temperature of the microelectromechanical resonator, an operating temperature of the microelectromechanical oscillator or an operating temperature of the frequency adjustment circuitry.

36. The microelectromechanical oscillator of claim 35 wherein the values are determined during (i) calibration of the microelectromechanical oscillator or (ii) operation of the microelectromechanical oscillator.

37. The microelectromechanical oscillator of claim 35 further including temperature sensors, integrated in or on the common substrate, to provide data which is representative of temperature to the temperature sensor circuitry.

38. A method of operating a microelectromechanical oscillator having (1) a microelectromechanical resonator, integrated in or on a substrate, to generate an output signal wherein the output signal includes a first frequency, and (2) frequency adjustment circuitry, coupled to the microelectromechanical resonator and integrated in or on the substrate, 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 (i) within a predetermined range of frequencies and (ii) greater than the first frequency, the method comprising:

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

providing a second set of values to the frequency adjustment circuitry, wherein the frequency adjustment circuitry, in response to the second set of values, generates an output signal having a frequency that is (1) within the predetermined range of frequencies when the microelectromechanical resonator is at the second operating temperature and (2) greater than the frequency of the output signal of the microelectromechanical resonator.

39. The method of claim 38 further including:

determining the 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 the predetermined range of frequencies when the microelectromechanical resonator is at the second operating temperature; and

storing the second set of values in a memory of the microelectromechanical oscillator.

40. The method of claim 38 further including:

measuring the temperature of the microelectromechanical resonator; and

calculating the operating temperature of the microelectromechanical resonator.

41. The method of claim 38 further including determining the second set of values during (i) testing of the microelectromechanical resonator and/or microelectromechanical oscillator, (ii) calibration of the microelectromechanical oscillator, or (iii) operation of the microelectromechanical oscillator.

42. The method of claim 38 wherein the frequency adjustment circuitry includes:

frequency divider circuitry to generate an output signal having a frequency using a first subset of values and the output signal of the microelectromechanical resonator;

frequency multiplier circuitry, coupled to the frequency divider circuitry, to generate the output signal of the frequency adjustment circuitry using a second subset of values and the output signal of the frequency divider circuitry; and

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

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

43. The method of claim 42 further including calculating the first and second subsets of values using empirical data or mathematical modeling.

44. The method of claim 42 further including determining the first and/or second subset of values during (i) testing of the microelectromechanical resonator or microelectromechanical oscillator, (ii) calibration of the microelectromechanical oscillator, or (iii) operation of the microelectromechanical oscillator.

45. The method of claim 38 wherein the frequency adjustment circuitry includes:

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

second frequency multiplier circuitry to generate the output signal of the frequency adjustment circuitry using a second subset of values wherein the second frequency is different from 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 providing the first subset of values to the first frequency multiplier circuitry and the second subset of values to the second frequency multiplier circuitry, wherein the frequency adjustment circuitry, in response to the first and second subsets of values, provides;

the output signal having the frequency that is (1) within the predetermined range of frequencies when the microelectromechanical resonator is at the second operating temperature and (2) greater than the frequency of the output signal of the microelectromechanical resonator, and

a second output signal having the frequency that is (1) within a predetermined range of frequencies when the microelectromechanical resonator is at the second operating temperature and (2) greater than the frequency of the output signal of the microelectromechanical resonator.

46. The method of claim 45 further including calculating the first and second subsets of values using empirical data or mathematical modeling.

47. The method of claim 45 further including determining the first and/or second subset of values during (i) testing of the microelectromechanical resonator or microelectromechanical oscillator, (ii) calibration of the microelectromechanical oscillator, or (iii) operation of the microelectromechanical oscillator.

48. The method of claim 38 wherein the frequency adjustment circuitry includes:

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

frequency divider circuitry, coupled to the first frequency multiplier circuitry, to receive the output signal of the first frequency multiplier circuitry and, using 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 microelectromechanical resonator; and

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

 

the method further comprises providing the first subset of values to the frequency multiplier circuitry and the second subset of values to the frequency divider circuitry, wherein the frequency adjustment circuitry, in response to the first and second subsets of values, provides the output signal having the frequency that is (1) within the predetermined range of frequencies when the microelectromechanical resonator is at the second operating temperature and (2) greater than the frequency of the output signal of the microelectromechanical resonator.

49. The method of claim 48 further including calculating the first and second subsets of values using empirical data or mathematical modeling.

50. The method of claim 48 further including determining the first and/or second subset of values during (i) testing of the microelectromechanical resonator or microelectromechanical oscillator, (ii) calibration of the microelectromechanical oscillator, or (iii) operation of the microelectromechanical oscillator.

51. A 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 resonator and, using a set of values and the output signal of the microelectromechanical resonator, to generate a plurality of output signals wherein at least one of the output signals includes a frequency that is greater than the first frequency; and

wherein the microelectromechanical resonator and the frequency adjustment circuitry are integrated in or on a common substrate.

52. The microelectromechanical oscillator of claim 51 wherein the set of values is determined, at least in part, using information which is representative of the first frequency.

53. The microelectromechanical oscillator of claim 52 wherein the first frequency depends, at least in part, on an operating temperature of the microelectromechanical resonator.

54. The microelectromechanical oscillator of claim 51 wherein the values are determined using empirical data or mathematical modeling.

55. The microelectromechanical oscillator of claim 51 wherein the values are determined during (i) testing of the microelectromechanical resonator and/or microelectromechanical oscillator, (ii) calibration of the microelectromechanical oscillator, or (iii) operation of the microelectromechanical oscillator.

56. The microelectromechanical oscillator of claim 51 wherein the frequency adjustment circuitry includes first and second frequency multiplier circuitry which are fractional-N PLLs or digital/frequency synthesizers.

57. The microelectromechanical oscillator of claim 51 wherein the frequency adjustment circuitry includes first and second frequency multiplier circuitry which are fractional-N PLLs or PLLs.

58. The microelectromechanical oscillator of claim 51 wherein the frequency adjustment circuitry includes first and second frequency multiplier circuitry and wherein:

the first frequency multiplier circuitry is a fractional-N PLL, an interger-N PLL, or a digital/frequency synthesizer; and

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

59. The microelectromechanical oscillator of claim 51 wherein the first frequency depends at least in part, on an operating temperature of the microelectromechanical resonator and wherein the microelectromechanical oscillator further includes temperature sensor circuitry to determine information which is representative of the operating temperature of the microelectromechanical resonator, an operating temperature of the microelectromechanical oscillator or an operating temperature of the frequency adjustment circuitry.

60. The microelectromechanical oscillator of claim 59 wherein the values are determined during (i) calibration of the microelectromechanical oscillator or (ii) operation of the microelectromechanical oscillator.

61. The microelectromechanical oscillator of claim 59 further including temperature sensors to provide data which is representative of temperature to the temperature sensor circuitry.

62. The microelectromechanical oscillator of claim 51 wherein the first frequency depends, at least in part, on an operating temperature of the microelectromechanical resonator and wherein the microelectromechanical oscillator further includes temperature sensor circuitry, integrated in or on the common substrate, to determine information which is representative of the operating temperature of the microelectromechanical resonator, an operating temperature of the microelectromechanical oscillator or an operating temperature of the frequency adjustment circuitry.

63. The microelectromechanical oscillator of claim 62 wherein the values are determined during (i) calibration of the microelectromechanical oscillator or (ii) operation of the microelectromechanical oscillator.

64. The microelectromechanical oscillator of claim 62 further including temperature sensors, integrated in or on the common substrate, to provide data which is representative of temperature to the temperature sensor circuitry.

65. The microelectromechanical oscillator of claim 62 wherein more than one of the output signals include frequencies that are greater than the first frequency.