Design and implementation of integrated front-end readout circuit for linear-array biosensors with chopper-stabilized operational amplifier

A readout circuit for the linear array pH sensor was designed and developed, using chopper stabilization technique. It consisted of analog multiplexer, chopper stabilized operational amplifier, level shift, filter and buffer stage. The operational amplifier used in this design was a folded cascade amplifier. Results showed that the circuit can reduce input offset, drift voltage and noise. Moreover, noise can be further reduced on a faster chopper frequency. This readout circuit can be used for measuring small signal of low frequency biosensor. The readout circuit design was implemented using TSMC 0.35um 2P4M standard CMOS process.