Chip-scale integrated driver for electrostatic DM control

Abstract

A CMOS electronics driver chip to control a deformable MEMS mirror has been developed. With the advances in CMOS technology, it has become possible to design and fabricate electronics operable at higher voltages than those in traditional integrated circuits. Since MEMS structures require relatively high operating voltages to achieve electrostatic force, these high voltage CMOS processes offer promise for miniaturization of the corresponding drivers. Using the capability of low voltage logic together with high voltage output stages, a compact driver chip has been designed and fabricated. The chip was developed and fabricated though a high voltage CMOS process. The driver is digitally controlled through address and data input bits, and through a smart low-voltage to high-voltage transition output stage, voltages of up to 300V are output to each mirror electrode. A compact design allows the control of 144 channels through a single chip with 8-bit resolution at 100Hz refresh rate. The low-voltage stage consists of address logic together with latch stages to store the data, which in turn is converted to a high voltage signal through a current mode, binary weighted scheme. This technique combines the digital-to-analogue conversion stage and a high-voltage amplifier stage, thus saving on substrate area. Using this method, the 144 channel high-voltage driver was fabricated on a single chip less than 3.5cm² in area. In this paper, design, fabrication and testing of these drivers are reported.