A Single-Platform Simulation and Design Technique for CMOS-MEMS Based on a Circuit Simulator With Hardware Description Language

This paper presents a multiphysics simulation and layout design technique for complementary metal-oxide-semiconductor-microelectromechanical systems (MEMS) (CMOS-MEMS) based on an electrical circuit simulator. An equivalent circuit model for the mechanical equation of motion has been translated into a Verilog-A-compatible hardware description language (HDL) in the Cadence Virtuoso environment to attain new designing capabilities such as automatic mask-layout synthesis, design rule check, and layout-versus-schematic verification for MEMS structures. Microelectromechanical components such as parallel-plate actuator and bending suspension, whose analytical equation models are already known, are also interpreted into HDL-coded equivalent circuits. Behavior of a MEMS device, including the electrostatic displacement hysteresis and the negative spring constant effect, is numerically simulated as a lumped mass-and-spring system, which has been verified to quantitatively agree with that of the corresponding analytical simulation results. A multiphysics model for the Colpitts oscillator circuit has been built in the developed simulation environment by replacing a quartz resonator with a compact model of an electrostatic silicon resonator, and its self-excited resonance has been confirmed by the simulation after the coordination of the device and circuit parameters. A prototype conversion tool for MEMS parameterized cell has also been developed to demonstrate automatic generation of mask layouts for a silicon resonator, which has been cross-checked against the experimental measurements to verify the simulation accuracy.