An efficient signal conditioning circuit to piecewise linearizing the response characteristic of highly nonlinear sensors

To obtain the solutions to the problem of linearization of the sensor characteristics is a matter of investigations for a long time. This paper presents a new and simple piecewise linearizing circuit to compensate the nonlinearity of highly nonlinear sensor. It is having a mixed signal conditioning circuit, employing a 2-bit flash ADC, a (4×1) multiplexer and the Op amp-based signal conditioning units. The circuit was initially simulated using SPICE software and then hardware implemented for linearizing the nonlinear response characteristic of two sensors. One of the sensors is a graphene oxide capacitive humidity sensor with nearly 46% nonlinearity and the other is a thermistor-based temperature sensor with 16.4% nonlinearity. The humidity sensor is fabricated and characterized to measure humidity in the range of 2-85% RH. The maximum nonlinearity of the humidity and temperature sensors of the hardware implemented circuit after compensation was 1% and 1.5% respectively. The circuit is simple and requires few hardware components for implementation and applicable for any nonlinear sensor. The circuit is CMOS compatible for ASIC implementation.