We present the first inertial microsensor stand-alone simulation tool capable of modeling an entire sensor system, 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. Sensor design methodology, modeling and simulation concerns are addressed. Results appear in a companion paper also published in this volume.