Characteristic analysis and study of an active matrix addressing for grating light modulator

Grating Light Modulator(GLM) based on MEMS is applied in projection display. In order to eliminate crosstalk of GLM array, a monolithic integration device of GLM and active matrix is presented with post-CMOS process. The operating principle of monolithic integration device is introduced. Active matrix unit is composed of a NMOS transistor and a capacitor. The bottom electrode of GLM is connected to the electrode of the capacitor by via, so the voltage of GLM equals to the voltage of capacitor. Every GLM unit is controlled by sole active matrix unit, so crosstalk can be eliminated, which improves optical contrast and optical utilization ratio. And, the monolithic integration process of active matrix and GLM is designed. Then the key indexes and parameters of active matrix which influences the performance of monolithic integration device are analyzed in detail. It's indicated by analysis that storage capacitor and width-length ratio of transistor influence the holding-voltage property and switch speed of monolithic integration device. Finally, with 0.18µm process design kit(PDK) of SMIC and Cadence software, layout of monolithic integration device is designed. The simulation results validate the correctness of the analyzed theory and the designed circuits. The monolithic integration device designed can be applied in projection display which has 1920×1080 resolution, 30Hz frame frequency and 256 grayscales.