Active ISFET sensor readout circuit

Abstract

An improved readout circuit interface for ion-sensitive field-effect transistor (ISFET) is proposed in this work. When compared with conventional topologies found on the literature, the proposed ISFET readout circuit presents at least two advantages. The first concerns the simplicity of the new circuity topology, and the second is the additional gain conferred to the sensor output signal. The performance of the proposed readout circuit integrated with the electrical ISFET model was investigated through BSIM3v3 simulations. The conventional ISFET readout topologies are found not to confer gain to the electrical ISFET output signal, and the sensor output signal has its limit predicted by the Nernst s model. Simulation results shows that the proposed ISFET readout circuit topology grants additional gain to the sensor output signal increasing its sensitivity up to three times the Nernst limit.