Model fitting of a SPICE Equivalent Circuit for the Design of Ferroelectric Liquid Crystal on Silicon Devices

摘要

Optimal performance of a Liquid Crystal on Silicon (LCoS) device requires an integrated approach incorporating both optical and electrical design elements. In particular, during the design of both the IC back plane and the voltage waveforms used to drive fast switching Ferroelectric LC (FLC) the electro-optical properties of the LC must be considered to ensure that the best use is made of the FLC. Although, SPICE equivalent circuits for FLC materials have been developed and can be used for this purpose their accuracy relies upon the measurement of a number of parameters. Unfortunately, the accuracy of measuring key parameters is often poor, resulting in a relatively large margin of error in the final model. However, this need not be the case. In this paper we present a methodology which uses standard IC parameter extraction software to simulate and optimize the FLC SPICE model parameters such that the model closely matches the measured response of the sample. By using this approach we identify a set of parameters which when combined provide a SPICE equivalent circuit which models the FLC response to a given input waveform.