A 92-dB-DR 126-μV Sensitivity Potentiometric Sensor Interface With High Interference Robustness

A fully differential Potentiometrie sensor interface consisting of a high input impedance programmable-gain preamplification stage followed by a delta-sigma (ΔΣ) ADC is presented. The reconfigurable circuit achieves a dynamic range of 92 dB and a resolution of 126 μν, thus enabling electrochemical analyses for multiple biochemical parameters. The fully differential topology of the signal acquisition chain in combination with the use of feedforward compensated opamps leads to a high interference robustness of the implementation. Compared to a single-ended topology, PSRR, CMRR and EMIRR improvements by 43.3 dB, 6.8 dB and 21.6 dB, respectively, are achieved. These properties and the low power and area consumption of 75 μW and 0.081 mm2 allow the circuit to be used in wirelessly powered electrochemical point-of-care (PoC) diagnostics.