A 14-bit low-power interface circuit for piezo-resistive pressure sensors

In this work, a new low-power interface circuit for Wheatstone bridge piezo-resistive pressure sensors is introduced. Different than conventional interface circuits, it is proposed to periodically switch the resistive bridge to save power. To reduce the interface power even further, the turn ON time of different system blocks is optimized. The proposed interface is composed of a sample-and-hold circuit, a front-end-amplifier and a ΔΣ analog-to-digital-converter. The interface circuit achieves a high resolution of 13.82 bits at a power consumption of 221.8μW, including the bridge power, in 0.13μm CMOS technology, with a supply voltage of 1.2V. Hence, a very low figure-of-merit of 5.076 pJ/Conversion is attained.