CMOS current attenuator for electrochemical sensing applications

A new CMOS current attenuator circuit is designed and demonstrated. The purpose of this circuit is to attenuate steady state current in conjunction with CMOS ADC readout circuits for electrochemical sensing applications. The circuit has been fabricated in a 5 V AMS CMOS process. Salient features include: (1) bi-directional input current range from 25 nA to 300 nA; (2) current attenuation of 55 dB; (3) non-linearity around 2 % over the entire input current range; (4) output DC offset current of around 200 pA; (5) power consumption around 0.35 mW.