Noise canceling chopper stabilized front-end for electrochemical biosensors with improved dynamic range

This paper presents a front-end circuit for electrochemical biosensors used in applications like DNA sensing. Novelty in this work lies in the front-end architecture which uses noise canceling (NC) combined with chopper stabilization (CS) for rejecting 1/f noise and to our knowledge, a front-end using the principle of noise canceling for 1/f noise rejection has not been reported. Motivation for using this front-end are: 1) The circuit exhibits low noise performance with its sensitivity not being limited by 1/f noise thanks to noise canceling and chopping. 2) The canceling property in this topology is used effectively to achieve improved linearity and higher dynamic range (DR) in addition to 1/f noise rejection. The fully differential front-end circuit is designed in 0.18 μm CMOS process and consumes 46 μA while operating on 1.8 V supply voltage. Based on the simulation results, a DR improvement of greater than 10 dB is achieved by the use of canceling technique.