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US 2014/0159826 A1Published application
Mems oscillators
AssigneeNXP B.V.
InventorsKim Phan Le, Jozef Thomas Martinus van Beek, Martijn Goossens
Life of this patent
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Abstract
The invention provides MEMS oscillator designs in which the thermal actuation and piezoresistive detection signals are separated. A first approach splits the frequency of the loop into two distinct components, an actuation frequency and a detection frequency. A second approach modifies the design of the MEMS resonator such that the actuation signal follows a different path through the MEMS resonator than the detection signal.
Claims15
An oscillator comprising:
- a MEMS resonator body;
- an AC current source for providing an AC current to a resonator input coupled to the resonator body, thereby to induce an alternating strain in the resonator by means of the thermal expansion effect to drive the resonator into resonance;
- and
- a piezoresistive read out sensor for monitoring a resistance of at least a portion of the resonator to derive an oscillating output signal at an output of the oscillator;
- and
- an oscillator circuit,
- wherein the oscillator circuit provides the ac current with a first frequency ω1 to actuate the resonator body and wherein a second different frequency ω2 is generated in the resonator by the piezoresistive effect to derive the output signal, wherein the oscillator circuit comprises a converter in a feedback control loop between the oscillator output and the resonator input for converting from the second frequency to the first frequency.
4 more elements
An oscillator comprising:
- a MEMS resonator body;
- an AC current source for providing an AC current to a resonator input coupled to the resonator body, thereby to induce an alternating strain in the resonator by means of the thermal expansion effect to drive the resonator into resonance;
- and
- a piezoresistive read out sensor for monitoring a resistance of at least a portion of the resonator based on a signal at a resonator output to derive an oscillating output signal at an output of the oscillator;
- and
- an oscillator circuit,
- wherein the AC current is provided to a first portion of the resonator and the piezoresistive read out is provided based on the resistance of a second portion of the resonator, the first portion and the second portion of the resonator are substantially electrically isolated.
4 more elements
Dependencies are inferred from the claim text.