A 6.5-μW 70-dB 0.18-μm CMOS Potentiostatic Delta-Sigma for Electrochemical Sensors

This paper presents the design of a low-power potentiostatic second-order continuous-time (CT) delta-sigma modulator (ΔΣM) for the amperometric read-out and A/D conversion of electrochemical sensors. The proposed architecture reuses the sensor itself as a leaky integrator stage for shaping the quantization noise, resulting in a very compact and energy efficient read-out front end. Low-power CMOS circuits are also presented for the remaining analog blocks of the ΔΣM loop. A design example in 0.18-μm CMOS technology is provided with a total area of 0.063mm
²
. Post-layout simulations show a dynamic range of 70dB with an overall power consumption of 6.5μW at 1.8-V supply.