We present the first report on a full-system integrated microsensor simulation model, based on discrete-time methods and implemented in SPICE. Included are all electrical and thermomechanical noise sources, proof mass dynamics, differential capacitive transducer bridge, interface circuit, and feedback control. Complete microsensor system performance can be simulated in the time domain, incorporating flicker noise models based on measured data from a commercial CMOS process. Simulation results for two complete inertial sensor system are presented: System I has an open loop resonant frequency of 100Hz, Q factor of 1000, and has a critically damped closed-loop resonance at 1.67kHz; System II is a critically damped open loop sensor with resonance at 1.67kHz. Closed loop operation is demonstrated to improve sensitivity by 106dB at 100Hz.