Low allan-deviation oscillator

1. A device comprising:

a microelectromechanical systems (MEMS) structure having a body that is to move, during a first phase, in a first direction away from a first position and, during a second phase, in a second direction away from the first position;

circuitry to produce an output signal that changes as a function of motion of the body relative to a sensor;

circuitry to detect change in the motion of the body between the first direction and the second direction;

wherein the circuitry to sense the motion and to produce the output signal comprises active compensation circuitry that is switched in dependence on the change in motion;

wherein the device comprises a first die and a second die which are bonded together and electrically-coupled;

wherein the MEMS structure is carried by the first die; and

wherein the circuitry to produce the output signal, the circuitry to detect change and the active compensation circuitry are carried by the second die.

2. The device of claim 1 , wherein:

the circuitry to produce comprises an amplifier circuit to receive a sense signal indicative of the motion of the body and to generate an amplified output signal in response to the sense signal; and

the active compensation circuitry is to perform offset cancelation to the amplifier circuit, the active compensation circuitry being switched in dependence on the change in motion.

3. A device comprising:

a microelectromechanical systems (MEMS) structure having a body that is to move, during a first phase, in a first direction away from a first position and during a second phase, in a second direction away from the first position;

circuitry to produce an output signal that changes as a function of motion of the body relative to a sensor;

circuitry to detect change in the motion of the body between the first direction and the second direction;

wherein the circuitry to sense the motion and to produce the output signal comprises active compensation circuitry that is switched in dependence on the change in motion;

wherein the circuitry to produce comprises an amplifier circuit to receive a sense signal indicative of the motion of the body and to generate an amplified output signal in response to the sense signal;

wherein the active compensation circuitry is to perform offset cancelation to the amplifier circuit, the active compensation circuitry being switched in dependence on the change in motion; and

wherein the active compensation circuitry comprises a detector circuit to assert, at a predetermined phase of the amplified signal, one or more control signals that enable an offset-reducing operation to reduce noise in the amplifier circuit.

4. The device of claim 3 , wherein the MEMS structure is a resonator that is to resonate at a frequency (f) and wherein the offset-reducing operation reduces (1/f) noise in the amplifier circuit.

5. The device of claim 4 , wherein:

the device comprises a first die and a second die which are bonded together and electrically-coupled;

the MEMS structure is carried by the first die; and

the circuitry to produce the output signal, the circuitry to detect change and the active compensation circuitry are carried by the second die.

6. The device of claim 5 , wherein the MEMS structure is a resonator.

7. A device comprising:

a microelectromechanical systems (MEMS) structure having a body that is to move, during a first phase, in a first direction away from a first position and, during a second phase, in a second direction away from the first position;

circuitry to produce an output signal that changes as a function of motion of the body relative to a sensor;

circuitry to detect change in the motion of the body between the first direction and the second direction;

wherein the circuitry to sense the motion and to produce the output signal comprises active compensation circuitry that is switched in dependence on the change in motion;

wherein the circuitry to produce comprises an amplifier circuit to receive a sense signal indicative of the motion of the body and to generate an amplified output signal in response to the sense signal;

wherein the active compensation circuitry is to perform offset cancelation to the amplifier circuit, the active compensation circuitry being switched in dependence the change in motion;

wherein the amplifier circuit comprises an input node coupled to receive the sense signal, an inverting amplifier having an input and an output and a variable capacitance element coupled between the input node and the input of the inverting amplifier; and

wherein the variable capacitance element is to be programmed at least once following manufacture of said device.

8. A device comprising:

a microelectromechanical systems (MEMS) structure having a body that is to move, during a first phase, in a first direction away from a first position and, during a second phase, in a second direction away from the first position;

circuitry to produce an output signal that changes as a function of motion of the body relative to a sensor;

circuitry to detect change in the motion of the body between the first direction and the second direction;

wherein the circuitry to sense the motion and to produce the output signal comprises active compensation circuitry that is switched in dependence on the change in motion;

wherein the circuitry to produce comprises a first amplifier circuit to receive a sense signal indicative of the motion of the body and to generate an amplified output signal in response to the sense signal;

wherein the active compensation circuitry is to perform offset cancelation to the first amplifier circuit, the active compensation circuitry being, switched in dependence on the change in motion;

wherein the circuitry to produce comprises a second amplifier circuit to receive a sense signal indicative of the motion of the body and to generate an amplified output signal in response to the sense signal; and

wherein the first amplifier circuit and the second amplifier circuit are complementary, and are to sense complement motion of the body during a respective one of first and second phases.

9. The device of claim 1 , wherein the circuitry to detect the change in motion comprises a zero-crossing detector.

10. A device comprising:

a microelectromechanical systems (MEMS) structure having a body that is to move, during a first phase, in a first direction away from a first position and, during a second phase, in a second direction away from the first position;

circuity to produce an output signal that chances as a function of motion of the body relative to a sensor;

circuitry to detect change in the motion of the body between the first direction and the second direction;

wherein the circuit sense the motion and to produce the output signal comprises active compensation circuitry that is switched in dependence on the chance in motion;

wherein the circuitry detect the change in motion comprises a zero-crossing detector; and

wherein the zero-crossing detector is to assert one or more control signals in response to detection of a first zero-crossing in a signal representing sensed motion of the body and is to deassert the one or more control signals in response to detection of a second zero-crossing in the signal representing sensed motion of the body.

11. A device comprising:

a package mounting a first die and a second die;

a microelectromechanical (MEMS) structure carried by the first die, wherein the MEMS structure has a body that is to move, during a first phase, in a first direction away from a first position and, during a second phase, in a second direction away from the first position, and a sensor that is to produce a sense signal that changes as a function of motion of the body relative to the sensor; and

processing circuitry carried by the second die, wherein the second die is to receive the sense signal from the first die, and wherein the processing circuitry includes circuitry to circuitry to detect change in the motion of the body between the first direction and the second direction, active compensation circuitry that is switched in dependence on the change in motion, and circuitry to produce an output signal in dependence on the sense signal and compensation provided by the active compensation circuitry.

12. The device of claim 11 , wherein the MEMS structure is a resonator and the output signal comprises a timing signal.

13. The device of claim 11 , wherein:

the circuitry to produce comprises an amplifier circuit to receive a sense signal indicative of the motion of the body and to generate an amplified output signal in response to the sense signal; and

the active compensation circuitry is to perform offset cancelation for the amplifier circuit, the active compensation circuitry being switched in dependence on the change in motion.

14. The device of claim 13 , wherein the active compensation circuitry comprises a detector circuit to assert, at a predetermined phase of the amplified signal, one or more control signals that enable an offset-reducing operation to reduce noise in the amplifier circuit.

15. The device of claim 13 , wherein the MEMS structure is a resonator that is to resonate at a frequency (f) and wherein the offset-reducing operation reduces (1/f) noise in the amplifier circuit.

16. The device of claim 13 , wherein the amplifier circuit comprises an input node coupled to receive the sense signal, an inverting amplifier having an input and an output and a variable capacitance element coupled between the input node and the input of the inverting amplifier, wherein the variable capacitance element is to be programmed at least once following manufacture of said device.

17. The device of claim 13 , wherein:

the amplifier circuit is a first amplifier circuit;

the circuitry to produce comprises a second amplifier circuit to receive a sense signal indicative of the motion of the body and to generate an amplified output signal in response to the sense signal; and

the first amplifier circuit and the second amplifier circuit are complementary, and are to sense complement motion of the body during a respective one of first and second phases.

18. The device of claim 11 , wherein the circuitry to detect the change in motion comprises a zero-crossing detector.

19. The device of claim 18 , wherein the zero-crossing detector is to assert one or more control signals in response to detection of a first zero-crossing in a signal representing sensed motion of the body and is to deassert the one or more control signals in response to detection of a second zero-crossing in the signal representing sensed motion of the body.

20. A device comprising:

a microelectromechanical (MEMS) resonator carried by a die, wherein the MEMS resonator has a body that is to move, during a first phase, in a first direction away from a first position and during a second phase, in a second direction, away from the first position, and a sensor that is to produce a sense signal that changes as a function of motion of the body relative to the sensor; and

processing circuitry to receive the sense signal and produce an output timing signal dependent on mechanically-resonant motion of the body, wherein the processing circuitry includes an amplifier circuit, circuitry to circuitry to detect change in the motion of the body between the first direction and the second direction, active compensation circuitry to provide offset compensation for the amplifier circuit, the active compensation circuitry being switched according to the change in motion;

wherein the amplifier circuit is a first amplifier circuit;

wherein the circuitry to produce comprises a second amplifier circuit to receive a sense signal indicative of the motion of the body and to generate an amplified output signal in response to the sense signal; and

wherein the first amplifier circuit and the second amplifier circuit are complementary, and are to sense complement motion of the body during a respective one of first and second phases.

21. The device of claim 20 , wherein the MEMS resonator is to resonate at a frequency (f) and wherein the offset-reducing operation is to reduce (1/f) noise in the amplifier circuit.

22. The device of claim 2 , wherein:

the amplifier circuit is a first amplifier circuit;

the circuitry to produce comprises a second amplifier circuit to receive a sense signal indicative of the motion of the body and to generate an amplified output signal in response to the sense signal; and

the first amplifier circuit and the second amplifier circuit are complementary, and are to sense complement motion of the body during a respective one of first and second phases.