Simulation of a capacitive pressure sensor with VHDL-AMS

In this work a pressure sensor microsystem compatible with the standard CMOS-process is described using the simulation language VHDL-AMS. The system is composed of an array of micromachined membranes and a read-out circuit realized in switched-capacitor technology. The mechanical behavior of the individual membranes was represented using linear and nonlinear models. Three different realizations of the read-out circuit, whose objective is to provide linearization and amplification of the capacitance-pressure characteristic, were tested. Among them, a balanced modulator was designed specifically for this particular application. The employed circuits were validated with the circuit simulator program SPICE and ported to VHDL-AMS. Finally the complete multi-domain microsystem, composed of an array of capacitive membranes, linearization and amplification circuits and an analog-to-digital converter, was simulated under the same framework provided by the simulation language VHDL-AMS. The realizability of complex multi-physics, mixed-signal systems with the help of free simulators was demonstrated.