A high-performance accelerometer with a fifth-order sigma–delta modulator

To verify the effectiveness of higher-order electromechanical sigma-delta modulator (EAM), a micromachined accelerometer is fabricated. The in-plane sensor with fully differential structure has a mechanical noise floor below static sensitivity 20pF/g and resonant frequency 325Hz. Analyses are performed to these key parameters. The silicon-on-glass sensor is fabricated by Deep Reactive Ion Etching (DRIE)and anodic bonding. Compared with a second-order electro-mechanical EAM, which only uses mechanical integration, the sensor is cascaded with additional electronic integrators to form a fifth-order electromechanical EAM, which leads to beter Signal to Quantization Noise Ratio (SQNR). Key words: Micromachined accelerometer, sigma-delta modulator.