A multi-step electromechanical ΣΔ converter for micro-g capacitive accelerometers

A multi-step electromechanical /spl Sigma//spl Delta/ modulator for /spl mu/g accelerometers is described. A two-element sensor array is used in two /spl Sigma//spl Delta/ loops and resolution improves by >2x compared to a conventional 2nd-order /spl Sigma//spl Delta/ modulator. This CMOS chip operates at 1 MHz and provides 0.2-1.2V/pF sensitivity, <20aF resolution, >120dB dynamic range, and dissipates <12mW.