A Continuous-Time Capacitance-to-Digital Converter for Floating-Target

Abstract

This article presents a high-performance continuous-time (CT) capacitance-to-digital converter (CDC) for floating-target displacement measurement applications. It uses a di fferential first-order RC low-pass filter (LPF) front end to convert parallel-plate capacitance to phase shift, which is further digitized by a high-resolution second-order CT phase-domain (PD) delta–sigma modulator (CT-PD ∆ΣM). The electrical field interference of the sensor, modeled as a capacitive-coupled charge on the common p