Chopper-Stabilized Bidirectional Current Acquisition Circuits for Electrochemical Amperometric Biosensors

Two low-noise bidirectional current acquisition circuits for interfacing with electrochemical amperometric biosensor arrays are presented. The first design is a switched-capacitor transimpedance amplifier (TIA). The second design is a current conveyer (CC) with regulated-cascode current mirrors. Both circuits employ chopper stabilization to reduce flicker noise. The TIA and the CC were prototyped in 0.13 μm CMOS and consume 3 μW and 4 μW from a 1.2 V supply, respectively. The electrical and electrochemical recording properties of both circuits have been characterized. The current conveyer exhibits superior performance in low-concentration electrochemical catalytic reporter sensing, as less switching noise is injected into the biosensor.