The MEMS-based accelerometer is extensively used in applications like automobile, avionics, etc. One system comprising of an accelerometer and its interface circuit were developed. An analog interface circuit has been developed for piezo-resistive MEMS accelerometer for application in Micro Air Vehicle (MAV). The system specifications were provided by CSIR-NAL. The designed circuit in the form of single monolithic silicon chip consists of an offset-compensation circuit, variable gain amplifier, ADC and buffer. The chip was fabricated using ams 0.35μm CMOS technology. Output offset voltage up to 150 mV could be compensated. A maximum gain of 45 V/V was achieved from designed variable gain amplifier. A 10-bit pipelined ADC converts the analog output of the amplifier into digital form. To control all the blocks of the interface circuit, appropriate algorithm was developed and implemented in Lab-View. The complete system has been tested using an in-house developed test arrangement. The versatility of the interface circuit was verified by interfacing with multiple ranges of accelerometers and testing their functionality with respect to a commercial reference accelerometer. Fig. 1 shows the layout of designed chip and Fig. 2 shows the results obtained from testing.
Fig. 1: Layout of fabricated ASIC
Fig. 2: Result obtained by testing the accelerometer with a shaker