Research On Detection Circuit Of MEMS Capacitive Sensors

A capacitive sensor is the sensor that includes a variable capacitor sensor which varies its capacitance with changes in an environmental parameter. Along with the fast development of the design and manufacturing level of MEMS, the research and application of the MEMS sensor are greatly accelerated. As an important branch of the intellectualized microcomputer electrical system series, MEMS sensor has so many advantages, such as smaller in volume,reliability. At present, acceleration sensors are widely used in the field of navigation and aerospace, industry auto-mation, car airbag control and so on.Typical signal processing circuits of micro capacitive sensors were analyzed in this study, and the characteristics of these circuits were compared.Because of the minimal output capacitor change of MEMS capacitive accelerometer, detecting circuit of MEMS capacitance based on the switched capacitor technology was selected. The bandgap voltage reference,self-biased current reference and relaxation oscillator modules were designed, and these basic units in analog integrated circuits were analyzed. Cadence layout design and validate tools were introduced and the layout design and validate process of the circuit was presented.