A wide-range micromachined threshold accelerometer array and interface circuit

Abstract

This paper presents a complete threshold acceleration detection microsystem comprising an array of threshold accelerometers and a low power interface circuit. The sensors were designed and fabricated using the bulk-silicon dissolved-wafer process. The process offers a wide latitude in sensor threshold levels, as demonstrated in the fabrication of devices with levels of 1.5-1000 g, bandwidths of 45 Hz to 40 kHz, with mass sizes ranging from 0.015 µg to 0.7 µg, and low-resistance gold-gold contacts for the switch. The interface circuit dissipates less than 300 µW, measures 2.2 mm×2.2 mm; it was fabricated in-house using a standard 3 µm, p-well CMOS (complementary metal oxide semiconductor) process, and is connected to the sensor chip in a multi-chip module. The key aspects of the microsystem are the implementation of sensor redundancy and supporting circuit logic to improve detection accuracy and fault tolerance, which are crucial factors in many applications. In addition, the microsystem supports communication with a standard microcontroller bus in a smart sensor network.