A Bandpass ΔΣ Interface IC for Sacrificial Bulk Micromachined Inertial Sensors

Abstract

A bandpass ΔΣ interface IC for sacrificial bulk micromachined inertial sensors is presented. To achieve high resolution without precision analog circuits, the proposed architecture replaces the analog mixer of a chopper-stabilized readout amplifier with a 1-bit, 4th-order bandpass ΔΣ modulator and a digital decimator/demodulator. Leveraging the high over-sampling ratio of 8192 and the supporting circuit techniques, the interface IC provides a 128-Hz, 20-bit digital output with 113 dB peak SNR and 115 dB dynamic range (DR). Fabricated in 0.18 μm CMOS, the IC dissipates 56.1 mW.