Sensors play the most important role in observing changes in an environment they are a\npart. They detect even the smallest changes and send the information to other electronic devices.\nMaking sure that these sensors provide an accurate output is equally crucial, as the data it measures\nand collects are used for analysis. Until now, calibrating sensors has been done manually by following\na sequence of procedures, and is usually performed on-site or in a laboratory prior to deployment.\nTo eliminate the manual procedure in the calibration (at the very least), an ion-sensitive field-effect\ntransistor (ISFET) with a built-in calibration registers circuit was created through segmented eight-bit\nbinary search in a three-point algorithm using a field-programmable gate array (FPGA). The circuit\nwas created using a three-point calibration algorithm and three standard buffers (pH 4, pH 7,\nand pH 10). The block diagram, schematic diagram, and the number of logic gates were derived after\nsynthesizing the Verilog program in Xilinx/FPGA. An average of 0.30% error was computed to prove\nthe reliability of the created circuit using FPGA. Having an ISFET with built-in calibration registers\nwill alleviate the work of experts in performing calibrations. This would follow the plug and play\nstandard, hence its being a calibration-ready ISFET device. With this feature, it could be used as a pH\nlevel meter or a remote sensor node in several applications.
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