A Bidirectional Current-Mirror-Based Potentiostat Using a Slice-Based Class-AB Amplifier

Abstract

A picoampere sensitive electrochemical sensor signal acquisition chain consisting of a multichannel bidirectional current-mirror -based potentiostat and a multiplexed current-input delta-sigma ( Δ Σ ) ADC is presented. Slice-based class-AB amplifiers with output stage current replication using reconfigurable current mirrors enable bidirectional current sensing over a range of five decades. The replicated current is digitized by the ADC. The proposed circuit achieves a minimum detectable current of 91.7 pA, resulting in a dynamic range of 147 dB for sensor currents up to ± 1 mA. The potentiostat is operated at a 3-V supply, the ADC at 1.5 V. The static power consumption of a single interface channel depends on the number of active amplifier slices and is between 14.1 and 39.3 μW. The highest power efficiency among similar systems and the low voltage headroom consumption of less than 500 mV enables a versatile use of the interface for multiple sensing applications.