A low noise accelerometer with digital PID-type controller and multibit force feedback

A hybrid acceleration sensing system is presented consisting of a micromachined acceleration sensor and a CMOS-IC. Due to closed loop operation, linearity, measurement range and bandwidth of the sensor device are extended by more than an order of magnitude. The system forms an electromechanical ΔΣ-converter featuring an autozero OP minimizing low frequency noise, a multibit D/A-converter reducing quantization noise and a digital PID-type controller shaping quantization noise and providing high bandwidth. Experimental results show a resolution of 15,5 bit and a linear operation range of ±52g.