Abstract
A high-order high-Q closed-loop sigma-delta (ΣΔ) capacitive microaccelerometer interface circuit is presented in this work. The quantization noise in baseband of the interface circuit is greatly suppressed by a high-order loop shaping, and the mechanical noise is deceased by the use of a vacuum-packaged sensor element. A lead compensator is used to damp the high-Q element to guarantee a stable high-order system. The interface circuit is implemented in a standard CMOS process, and the power dissipation is 10 mW from a 5 V supply and sampling frequency of 250 kHz. The high-order high-Q closed-loop ΣΔ capacitive microaccelerometer has a noise floor of 5 µg/Hz1/2 with bandwidth of 600 Hz.
