An energy-efficient heterogeneously-integrated capacitive pressure sensing system

Ultra-low power, miniaturized pressure sensors have attracted renewed interest in recent years thanks to emerging applications in altimetry as well as intra-ocular and intracranial pressure monitoring. The energy efficiency of these systems is however often limited by MEMS-CMOS interconnection parasitics. In this work, we employ a commercially-available MEMS-CMOS process designed for inertial sensors to realize a pressure-sensing microsystem in which the membrane is bonded on top of the CMOS die, decreasing the parasitic capacitance and enabling direct successive approximation conversion. The system is integrated in 2.2 × 2.6 × 0.4mm3 and performs 12bit digitization over 520mmHg pressure range with 130nW power consumption at 650S/s.