ISFET interface circuit embedded with noise rejection capability

A new constant-current voltage driver forms a bridge-type floating drain-source follower configuration applicable to the determination of H/sup +/ ion concentration. The proposed circuit maintains the ion-selective field effect transistor (ISFET) in an accurate constant drain-source voltage and current situation with good noise rejection capability. Simulation results show accurate response for ISFET applications. The presented electronic circuit can be integrated with a ISFET-based microsystem by standard CMOS technology.