AN INTEGRATED FORCE-BALANCED CAPACITIVE ACCELEROMETER FOR LOW-G APPLICATIONS

A low-cost monolithic accelerometer which incorporates a surface-micro machined polysilicon sensor with bipolar/MOS interface circuitry on a simple chip has been developed for a measurement range of +/- 5g. The accelerometer has a noise floor of 0.6 mg (Hz)(-1/2) and a shock survi val rating or 1000g. A sensitivity temperature coefficient of +/- 50 p pm degrees C-1 and an offset temperature coefficient of +/- 5 mg degre es C-1 have been achieved over the - 40 to + 105 degrees C automotive temperature range, A wide bandwidth from d.c, to 4 kHz is adjustable u sing a single external capacitor. The accelerometer operates on a sing le 5 V power supply and consumes 40 mW of power. It provides an analog output of 200 mV g(-1) and a digitally activated self-test output of - 5g.