A 187-dB FoM S Power-Efficient Second-Order Highpass 16 Capacitance-to-Digital Converter

Abstract

The escalating demand for high-resolution sensor interface systems, driven by the proliferation of the Inter- net of Things (IoT) and wearable smart devices, has led to the widespread use of capacitive sensing transducers. These transducers are valued for their low-noise and low-power charac- teristics, making them suitable for various applications, including environmental and biomedical sensing. However, designing a high-resolution capacitive sensor interface system while main- taining power efficiency remains challenging. This article proposes a high-resolution energy-efficient highpass (HP) 16 capacitance-to-digital converter (CDC) architecture. The archi- tecture incorporates a 2nd-order HP 16 modulator (16M) and a continuous-time capacitance-to-voltage converter (CT CVC). The proposed CDC achieves an excellent capacitance resolution of 5.85 aF rms, with a power efficiency of 46 fJ/conversion-step and an FoMS of 187.4 dB. The HP 16M, designed with superior power efficiency, offers a promising solution for high-resolution capacitive sensor applications. Compared to state-of-the-art, the proposed CDC achieves more than 2× FoMS improvement while maintaining competitive FoM W.