Refet Replication For Isfet-Based Snp Detection Arrays

In-pixel differential measurement with calibration for chemical reaction occurrence detection, particularly for pH-based Single Nucleotide Polymorphism (SNP) detection and genotyping arrays is presented. The proposed work adjusts the offset of upto 130 mV between the ISFETs and the REFET in a calibration step and cancels out common mode noise by differential pairs with a 63.5 dB CMRR. Conventionally in such arrays Ion-sensitive Field-effect Transistors were used as sensors with interface circuitry, requiring conversion of the signal prior to processing. In this system they form part of the conditioning circuitry, improving the signal-to-noise ratio and easing the design constraints of intelligent large scale system-on-chips.