OSCILLATORS HAVING ARBITRARY FREQUENCIES AND RELATED SYSTEMS AND METHODS

• US 20110148531A1
• Filed: 03/10/2010
• Published: 06/23/2011
• Est. Priority Date: 12/23/2009
• Status: Active Grant

• Current Assignee: Analog Devices, Inc.
• Original Assignee: Sand9, Inc.
• Inventors: Kuypers, Jan H., Rebel, Reimund, Schoepf, Klaus Juergen
• Granted Patent: US 8,736,388 B2
• Time in Patent Office: Days
• US Class Current: 331/18
• CPC Class Codes: H03B 19/00 Generation of oscillations by non-regenerative frequency multiplication or division of a signal from a separate source transference of modulation from one carrier to another H03D7/00
• CPC Class Codes: H03B 5/30 with frequency-determining element being electromechanical resonator
• CPC Class Codes: H03B 5/32 being a piezoelectric resonator selection of piezoelectric material H10N30/00
• CPC Class Codes: H03C 3/095 applying frequency modulation to the loop in front of the voltage controlled oscillator
• CPC Class Codes: H03J 7/065 the counter or frequency divider being used in a phase locked loop
• CPC Class Codes: H03L 7/0991 the oscillator being a digital oscillator, e.g. composed of a fixed oscillator followed by a variable frequency divider H03L7/0995 takes precedence; fixed oscillators with means for selecting among various phases H03L7/0814
• CPC Class Codes: H03L 7/18 using a frequency divider or counter in the loop H03L7/20, H03L7/22 take precedence
• 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: H04B 1/40 Circuits

Abstract

Systems and methods for operating with oscillators configured to produce an oscillating signal having an arbitrary frequency are described. The frequency of the oscillating signal may be shifted to remove its arbitrary nature by application of multiple tuning signals or values to the oscillator. Alternatively, the arbitrary frequency may be accommodated by adjusting operation one or more components of a circuit receiving the oscillating signal.

Claims

1. A method of generating an oscillating signal having a target frequency from an oscillator having a mechanical resonator, the oscillator being coupled to a circuit to provide the oscillating signal to the circuit, the method comprising:

applying to the oscillator, from the circuit, a first tuning signal having a first value; and

applying to the oscillator, from the circuit, an automatic frequency control (AFC) tuning signal having a second value different than the first value.

2. The method of claim 1, wherein first tuning signal and the AFC tuning signal form different components of the same signal.

3. The method of claim 1, further comprising generating the first tuning signal.

4. The method of claim 3, further comprising providing, from the oscillator to the circuit, at least one value indicative of a frequency of the oscillator and/or the mechanical resonator, and wherein the first tuning signal is generated in response to receiving the at least one value.

5. The method of claim 3, further comprising receiving, at the circuit, the oscillating signal from the oscillator, comparing a frequency of the oscillating signal to a reference signal having the target frequency, and generating the first tuning signal in response to the frequency of the oscillating signal differing from the target frequency of the reference signal.

6. The method of claim 1, further comprising:

receiving, at the circuit, the oscillating signal from the oscillator;

synthesizing, using a frequency synthesizer, a synthesized signal having a synthesized frequency different than a frequency of the oscillating signal.

7. The method of claim 6, wherein the frequency synthesizer is a programmable frequency synthesizer having discrete frequency steps and wherein synthesizing the synthesized signal comprises setting the programmable frequency synthesizer to a setting indicated in a reference table, the reference table identifying settings to which to set the frequency synthesizer such that the synthesized signal has the target frequency for a given frequency of the oscillating signal.

8. The method of claim 7, wherein the reference table is stored in memory coupled to the frequency synthesizer.

9. The method of claim 1, wherein the first tuning signal is a digital signal.

10. The method of claim 9, wherein the first tuning signal is a digital code.

11. The method of claim 1, wherein the first tuning signal adjusts a frequency of the oscillating signal by between 10 ppm and 500 ppm.

12. The method of claim 11, wherein the first tuning signal adjusts the frequency of the oscillating signal by between 10 ppm and 100 ppm.

13. The method of claim 1, wherein the first tuning signal adjusts a frequency of the oscillating signal by up to approximately 10,000 ppm.

14. An apparatus comprising:

an oscillator having a mechanical resonator, at least one input port, and at least one output port, the oscillator configured to provide an oscillating output signal at the at least one output port;

a circuit having at least one input port coupled to the at least one output port of the oscillator to receive the oscillating output signal, and further having at least one output port coupled to the at least one input port of the oscillator,

wherein the circuit is configured to provide at its at least one output port at least one tuning signal for tuning the oscillator, the at least one tuning signal comprising an automatic frequency control (AFC) tuning signal and at least one additional tuning signal.

15. The apparatus of claim 14, wherein the AFC tuning signal and the at least one additional tuning signal form a single signal that is provided from the at least one output port of the circuit.

16. The apparatus of claim 14, wherein the at least one output port of the circuit comprises a first output port and a second output port, and wherein the first output port of the circuit is configured to provide the AFC tuning signal and the second output port of the circuit is configured to provide the at least one additional tuning signal.

17. The apparatus of claim 14, wherein the mechanical resonator is a quartz crystal resonator.

18. The apparatus of claim 14, wherein the mechanical resonator is a microelectromechanical systems (MEMS) resonator comprising a piezoelectric material.

19. The apparatus of claim 14, wherein the oscillator is formed on a first semiconductor die and the circuit is formed on a second semiconductor die.

20. An apparatus, comprising:

an oscillator comprising a mechanical resonator and a memory storing at least one value indicative of a frequency of the oscillator and/or of the mechanical resonator.

21. The apparatus of claim 20, wherein the mechanical resonator is a microelectromechanical systems (MEMS) resonator.

22. The apparatus of claim 20, wherein the at least one value indicative of a frequency of the oscillator and/or of the mechanical resonator is a value of a frequency of the oscillator.

23. The apparatus of claim 20, wherein the at least one value indicative of a frequency of the oscillator and/or of the mechanical resonator is a value of an offset of a frequency of the oscillator from a reference frequency.

24. The apparatus of claim 20, wherein the at least one value indicative of a frequency of the oscillator and/or of the mechanical resonator is a value of a frequency of the mechanical resonator.

25. The apparatus of claim 20, wherein the at least one value indicative of a frequency of the oscillator and/or of the mechanical resonator is a value of an offset of a frequency of the mechanical resonator from a reference frequency.

26. The apparatus of claim 20, wherein the oscillator comprises a first output port configured to provide an oscillating output signal of the oscillator and a second output port configured to provide the value indicative of the frequency of the oscillator and/or of the mechanical resonator.

27. A system comprising the apparatus of claim 26 and a processing circuit coupled to the oscillator and configured to receive the oscillating output signal of the oscillator.

28. The system of claim 27, wherein the processing circuit comprises a first input port coupled to the first output port of the oscillator and a second input port coupled to the second output port of the oscillator.

29. The system of claim 28, wherein the processing circuit comprises a frequency synthesizer coupled to the first input port of the processing circuit and configured to receive the oscillating output signal of the oscillator and generate a synthesized signal having a frequency different than a frequency of the oscillating output signal.

30. The system of claim 29, wherein the frequency synthesizer comprises a phase-locked loop (PLL).

31. The system of claim 29, wherein the mechanical resonator is on a first semiconductor die and the frequency synthesizer is on a second semiconductor die.

32. A method comprising:

outputting, from an oscillator comprising a mechanical resonator to a circuit coupled to the oscillator, at least one value indicative of a frequency of the oscillator and/or of the mechanical resonator.

33. The method of claim 32, further comprising storing the at least one value in memory of the oscillator.

34. The method of claim 32, wherein the at least one value indicative of a frequency of the oscillator and/or of the mechanical resonator is a value of a frequency of the oscillator.

35. The method of claim 32, wherein the at least one value indicative of a frequency of the oscillator and/or of the mechanical resonator is a value of an offset of a frequency of the oscillator from a reference frequency.

36. The method of claim 32, wherein the at least one value indicative of a frequency of the oscillator and/or of the mechanical resonator is a value of a frequency of the mechanical resonator.

37. The apparatus of claim 32, wherein the at least one value indicative of a frequency of the oscillator and/or of the mechanical resonator is a value of an offset of a frequency of the mechanical resonator from a reference frequency.

38. The method of claim 32, further comprising outputting an oscillating signal from the oscillator.

39. The method of claim 32, wherein the oscillator is disposed on a first semiconductor die and the circuit coupled to the oscillator is disposed on a second semiconductor die.

40. The method of claim 32, further comprising applying to the oscillator, from the circuit coupled to the oscillator, a signal adjusting a frequency of an oscillating signal output from the oscillator.

41. The method of claim 40, wherein the oscillator is disposed on a first semiconductor die and the circuit coupled to the oscillator is disposed on a second semiconductor die.