Cascaded oscillator designs
An oscillator includes a resonator, sustaining circuit and detector circuit. The sustaining circuit receives a sense signal indicative of mechanically resonant motion of the resonator generates an amplified output signal in response. The detector circuit asserts, at a predetermined phase of the amplified output signal, one or more control signals that enable an offset-reducing operation with respect to the sustaining amplifier circuit.
1. An oscillator integrated circuit device comprising:
a first microelectromechanical systems (MEMS) resonator that produces a first timing signal;
a second MEMS resonator that produces a second timing signal;
a locked-loop circuit that receives each of the first timing signal and the second timing signal; and
wherein the locked-loop circuit produces an output timing signal that tracks phase noise of the first resonator below a first frequency and that tracks phase noise of the second resonator above the first frequency; and
wherein the first MEMS resonator is characterized by lower near phase noise than the second MEMS resonator.
2. The oscillator integrated circuit device of claim 1 wherein the first timing signal has a frequency dependent on a sensed frequency of the first MEMS resonator.
3. The oscillator integrated circuit device of claim 2 wherein the second timing signal has a frequency dependent on a sensed frequency of the second MEMS resonator.
4. The oscillator integrated circuit device of claim 1 wherein a first one of the first MEMS resonator and the second MEMS resonator produces a frequency that is greater than 35 megahertz and a second one of the first MEMS resonator and the second MEMS resonator produces a frequency that is less than 35 megahertz.
5. The oscillator integrated circuit device of claim 1 wherein:
the oscillator integrated circuit device further comprises at least one structure that is to serve as a temperature sensor;
the first timing output signal has a temperature corrected frequency, derived from a sensed frequency of the first MEMS resonator and temperature as measured by the temperature sensor.
6. The oscillator integrated circuit device of claim 5 wherein the at least one structure comprises the first MEMS resonator and a third MEMS resonator.
7. The oscillator integrated circuit device of claim 6 wherein at least one of the first MEMS resonator and the third MEMS resonator is a piezoelectric resonator.
8. The oscillator integrated circuit device of claim 6 wherein at least one of the first MEMS resonator and the third MEMS resonator is an electrostatic resonator.
9. The oscillator integrated circuit device of claim 1 wherein the second MEMS resonator comprises a piezoelectric resonator.
10. The oscillator integrated circuit device of claim 1 , further comprising a temperature compensated oscillator, the temperature compensated oscillator comprising the first resonator and producing the first timing signal.
11. The oscillator integrated circuit device of claim 1 wherein:
the oscillator integrated circuit device comprises a die;
the first MEMS resonator comprises a body on the die, the body to deflect or vibrate during operation of the oscillator; and
the oscillator integrated circuit device further comprises circuitry comprising a sustaining amplifier circuit to provide a drive signal to excite the body to deflect or vibrate during operation of the device;
the circuitry is operable to assert a control signal that enables offset-cancellation for the sustaining amplifier circuit at times established as a function of the control signal; and
the circuitry is to switch off the sustaining amplifier circuit during the times at which the offset-cancellation is enabled.
12. The oscillator integrated circuit device of claim 11 wherein:
the sustaining amplifier circuit is a first sustaining amplifier circuit, the times are first times, the control signal is a first control signal, and the offset cancelation is first offset cancellation;
the circuitry comprises a second sustaining amplifier circuit that is to provide a drive signal to excite the body to deflect or vibrate during operation of the oscillator;
the circuitry is further to assert a second control signal that enables for offset-cancellation for the second sustaining amplifier circuit at second times established as a function of the second control signal; and
the circuitry is to switch off the second sustaining amplifier circuit during the second times.
13. The oscillator integrated circuit device of claim 12 wherein the circuitry is to switch on the first sustaining amplifier circuit and is to switch on the second sustaining amplifier circuit at mutually-exclusive times.
14. The oscillator integrated circuit device of claim 12 wherein the body is to vibrate with a frequency of vibration and wherein the first offset cancellation and the second offset cancellation are each applied at the frequency of vibration, at predetermined, respective phases.
15. The oscillator integrated circuit device of claim 12 wherein the body is to vibrate with a frequency of vibration and wherein the first offset cancellation and the second offset cancellation are each applied at respective phases of an offset cancellation frequency, the offset cancellation frequency being less than the frequency of vibration.
16. The oscillator integrated circuit device of claim 11 wherein the body is to vibrate with a frequency of vibration and wherein the offset cancellation is applied at the frequency of vibration, at a particular phase relative to the frequency of vibration.
17. The oscillator integrated circuit device of claim 11 wherein the body is to vibrate with a frequency of vibration and wherein the offset cancellation is applied at an offset cancellation frequency, the offset cancellation frequency being less than the frequency of vibration.
18. The oscillator integrated circuit device of claim 1 wherein the oscillator integrated circuit device further comprises a sustaining amplifier, the first timing signal dependent on operation of the sustaining amplifier, the sustaining amplifier having a bipolar junction circuit structure.
19. The oscillator integrated circuit device of claim 1 wherein the output timing signal is characterized by a 1/f noise corner that is at a lower frequency than the Leeson integration corner of the oscillator integrated circuit device.
20. The oscillator integrated circuit device of claim 19 wherein the 1/f noise corner is less than or equal to ten hertz.
21. The oscillator integrated circuit device of claim 1 embodied as a packaged integrated circuit device, further comprising a contact or pin to output a frequency-multiplied clock signal.
22. The oscillator integrated circuit device of claim 1 wherein the oscillator integrated circuit device comprises a sustaining amplifier, the first timing signal being dependent on operation of the sustaining amplifier, the sustaining amplifier and the first resonator forming a type III oscillator.
23. The oscillator integrated circuit device of claim 22 wherein the second resonator is characterized by lower far phase noise than the type III oscillator.
24. The oscillator integrated circuit device of claim 1 wherein the first resonator is an electrostatic resonator.
25. The oscillator integrated circuit device of claim 1 wherein the oscillator integrated circuit device comprises a sustaining amplifier, the first timing signal being dependent on operation of the sustaining amplifier, and wherein the sustaining amplifier and the first resonator form part of a temperature compensated oscillator.
26. An oscillator integrated circuit device comprising:
a first MEMS resonator that produces a first timing signal, the first MEMS resonator being an electrostatic resonator;
a second MEMS resonator that produces a second timing signal;
a locked-loop circuit that receives each of the first timing signal and the second timing signal, the locked-loop circuit configured to produce an output timing signal that tracks phase noise of the first resonator below a first frequency and that tracks phase noise of the second resonator above the first frequency; and
a contact or pin to receive the output timing signal for output by oscillator integrated circuit device;
wherein the first MEMS resonator is characterized by lower near phase noise than the second MEMS resonator and wherein the second MEMS resonator is characterized by lower far phase noise than the first MEMS resonator.
27. The oscillator integrated circuit device of claim 26 wherein the second MEMS resonator is a piezoelectric resonator.
28. The oscillator integrated circuit device of claim 26 wherein:
the oscillator integrated circuit device further comprises a third MEMS resonator; and
the oscillator integrated circuit device is to provide temperature compensation dependent on an output of the third MEMS resonator.
29. The oscillator integrated circuit device of claim 28 wherein the third MEMS resonator is an electrostatic resonator.
30. The oscillator integrated circuit device of claim 1 wherein the first frequency corresponds to a loop rate of the locked loop.
31. The oscillator integrated circuit device of claim 26 wherein the first frequency corresponds to a loop rate of the locked loop.