A ±15V interface IC for capacitive accelerometer

In this study, an interface IC for capacitive accelerometer sensor was designed, was processed in 6 um standard bipolar process, and the IC operates in the supply voltage ranges ±6 V-±18 V. The IC consists of an active square wave generator, a symmetrical voltage reference, a low-capacitance high-impedance voltage buffer, demodulation block, pre-amplifier, self-testing module, etc. It can form a complete self-testable one-dimensional accelerometer together with a MEMS differential capacitive acceleration sensor, without any other active devices. At a supply voltage of ±15 V, the tested results are as follows. The scale factor is 60 mV/g, low-frequency noise is 26 mg_rms, 30-min zero drift is 54 mg, zero temperature drift in the range -40°C to 60°C is -13 mg/°C, response frequency reaches 2 kHz, and total power consumption is 48 mW only.