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

Abstract

A pico-ampere sensitive electrochemical sensor signal acquisition chain consisting of a multi-channel bidirectional current-mirror based potentiostat and a multiplexed current-input delta-sigma (AM) 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 µW 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.

A Floating Differential DAC Expands the Output Voltage Range for Electrochemical Measurements

“…Our proposed floating differential DAC is part of an integrated potentiostat [28] and manufactured in a 130 nm standard CMOS process. The DAC is designed for a supply voltage of 3 V, but can operate at supply voltages down to 2 V. Decreasing the supply voltage decreases the DACs output voltage range.…”

“…. Micrograph of the manufactured integrated potentiostat[28] with a layout overlay. The DAC and the positioning circuit are shown in more detail.…”

A Floating Differential DAC Expands the Output Voltage Range for Electrochemical Measurements

“…Our proposed floating differential DAC is part of an grated potentiostat [28] and manufactured in a 130 nm standard process. The DAC is designed for a supply voltage of 3 V, but can operate at supply voltages down to 2 V. Decreasing the supply voltage decreases the DACs output voltage range.…”

A 92-dB-DR 126-μν Sensitivity Potentiometrie Sensor Interface with High Interference Robustness

“…The scaled sensor signal at the output of the preamplification stage is converted by a ∆Σ ADC. The ADC is an advanced version of the circuit proposed in [12]. A secondorder continuous-time loop filter topology with an inherent anti-aliasing property is used.…”