MEMS oscillator
AssigneeSeiko Instruments Inc.
InventorKensuke Ogasawara
Life of this patent
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Abstract
Provided is a MEMS oscillation circuit which performs temperature compensation of a MEMS resonator with a simple circuit, which is mild so that an output clock does not have jitter, and which makes the range of fluctuations of a reference frequency from a reference value equivalent to a range of digital processing. The MEMS oscillator includes a MEMS resonator, a temperature measurement unit for measuring a temperature and outputting a detected voltage corresponding to the temperature, and a bias voltage control circuit for applying the MEMS resonator with a bias voltage which changes the resonant frequency of the MEMS resonator in a manner opposite to a change of the resonant frequency of the MEMS resonator due to temperature change correspondingly to the detected voltage.
Claims10
An MEMS oscillator comprising:
- an MEMS resonator configured to oscillate at a resonant frequency which is a function of a bias voltage applied to the MEMS resonator;
- a temperature sensor configured to output a signal indicative of a temperature of the MEMS resonator, wherein the signal from the temperature sensor has a voltage that changes proportionally to a change of the temperature;
- and
- a bias voltage controller configured to apply the bias voltage determined based on the signal from the temperature sensor,
- wherein the bias voltage controller comprises an amplifier configured to translate a deviation of the voltage of the signal from a reference voltage into the bias voltage to compensate the change of the resonant frequency caused by the change of the temperature,
- wherein the amplifier comprises:
- a first input terminal to which the signal from the temperature sensor is supplied;
- an output terminal connected to a reference voltage circuit via serially connected first and second resistors;
- and
- a second input terminal connected to a joint between the first and second resistors,
- wherein the reference voltage is a voltage at the joint, and the bias voltage is proportional to a difference between the voltage of the signal and the reference voltage multiplied by a ratio between the resistances of first and second resistors.
A method for compensating a change of a resonance frequency of an MEMS oscillator caused by a change of a temperature, comprising:
- providing an MEMS resonator configured to oscillate at a resonant frequency which is a function of a bias voltage applied to the MEMS resonator;
- measuring a temperature of the MEMS resonator and outputting a temperature signal indicative of the temperature of the MEMS resonator;
- and
- applying the bias voltage determined based on the temperature signal to compensate the change of the resonant frequency caused by the change of the temperature,
- wherein applying the bias voltage comprises:
- translating a deviation of the voltage of the temperature signal supplied to a first amplifier input from a reference voltage supplied to a second amplifier input into the bias voltage supplied at an amplifier output, wherein the reference voltage is a voltage at a joint between first and second resistors connected serially between a reference voltage source and the amplifier output.
Dependencies are inferred from the claim text.