A 15-μW 105-dB 1.8-Vpp potentiostatic delta-sigma modulator for wearable electrochemical transducers in 65-nm CMOS technology

Abstract

Wearable electrochemical sensors represent a point of convergence between lab-on-a-chip technologies, advanced microelectronics and connected intelligence. These three pillars establish data flow from analytes present in body fluids, to the Cloud infrastructures towards next-generation personal health-care and wellness. The design of electrode-embedded interfacing instrumentation in advanced CMOS technology nodes offer a number of challenges spanning from ultra-low power operation, small footprint, sufficient general purpose operability, and compatibility with advanced CMOS technology nodes. This paper presents a low-power frontend with extended amperometric dynamic range and wide potentiostatic range for electrochemical transducers with Delta-Sigma (Δ Σ) digital output. The second-order single-bit continuous-time Δ Σ modulator architecture reuses the electrochemical cell dynamic characteristics for quantization noise shaping, while the differential potentiostat enables 1.8Vpp of control range under single 1.2-V supply. The proposed frontend has been integrated in TSMC 65-nm CMOS technology occupying 0.07 mm2. From electrical and electrochemical tests, the micro potentiostat achieves a Signal-to-Distortion-and-Noise of 80dB with 15- μW power consumption and a combined multi-scale dynamic range of 105dB.