Using pseudo electrostatic spring constant to optimize the electromechanical Sigma-Delta accelerometer

The concept of pseudo electrostatic spring constant is introduced and a new system architecture incorporating which in an electromechanical sigma-delta modulator (EM-SDM) is proposed in this paper. The zeros in the quantization noise transfer function, corresponding to the sensor mechanical poles in the proposed system architecture, can be adjusted and optimized without affecting the sigma-delta closed-loop stability. The proposed system for a 3 rd -order dual-quantization EM-SDM accelerometer is designed, analyzed and simulated. The system is implemented with ASIC and FPGA on PCBs. The test results show that the system noise can be lowered by 6 dB after optimization in comparison with conventional EM-SDM.