Design and Simulation of an Ion Sensitive Field Effect Transistor (ISFET) Readout Circuit, with Low Thermal Sensitivity

EasyChair Preprint 2478

Abstract

Ion Sensitive Field Effect Transistor (ISFET) is one of the biological and/or chemical sensors compatible with the CMOS technology. The sensitivity of the ISFET is measured connecting the device to a readout circuit that provides an output voltage related to the threshold voltage shift according to the ion concentration. However, the influence of the temperature on the whole system (Electrolyte-ISFET-Readout circuit) is critical for proper processing. The proposed readout circuit tends to minimize the thermal sensitivity of the sensor circuit. The simulation was done using the AMI 1µm CMOS process provided by MOSIS, while the Verilog-A was used to model a pH-ISFET behavior. Simulation results with 3V supply voltage and a temperature range from 20°C to 80°C, shows a pH sensitivity of 40 mV/pH with thermal sensitivity less than 0.0005517pH/°C. The coefficient of determination R2 is around 0.999984 at T = 20°C and quantify the strength of the linear relationship.

Keyphrases: Ion-sensitive FET (ISFET), chemical sensors, temperature insensitive.

@booklet{EasyChair:2478,
  author    = {Abdelkhalak Harrak and Salah Eddine Naimi},
  title     = {Design and Simulation of an Ion Sensitive Field Effect Transistor (ISFET) Readout Circuit, with Low Thermal Sensitivity},
  howpublished = {EasyChair Preprint 2478},
  year      = {EasyChair, 2020}}