Patent ID: 8665011

Claim:
A micro electro-mechanical system (MEMS) circuit capable of compensating capacitance variation, the MEMS circuit comprising: a MEMS differential capacitor comprising a first capacitor and a second capacitor; a read-out circuit coupled to the MEMS differential capacitor for reading a difference between the first capacitor and the second capacitor in a zero-G condition, and generating an output signal according to the difference; a control circuit coupled to the read-out circuit for receiving the output signal, and generating a control signal; and a compensation circuit coupled to the control circuit for compensating the MEMS differential capacitor according to the control signal, wherein the compensation circuit comprises: a first switch having a first terminal coupled to a first terminal of the first capacitor, a second terminal for receiving the control signal, and a third terminal; a second switch having a first terminal coupled to the third terminal of the first switch, a second terminal for receiving the control signal, and a third terminal coupled to a second terminal of the second capacitor; a third switch having a first terminal coupled to the third terminal of the first switch, a second terminal for receiving the control signal, and a third terminal coupled to ground; and a variable capacitor coupled between the third terminal of the first switch and a second terminal of the first capacitor, wherein the variable capacitor changes a capacitance value of the variable capacitor to compensate the MEMS differential capacitor according to the control signal.