ABSTRACT
It was discussed in Sections 2.2.2 and 2.2.5 that sensors possess undesirable characteristics due to which the outputs deviate from the ideal or true values. This characteristic of asensor is known as nonlinearity. Linearity describes how closely the sensor output relates to aspecied suitable straight line, which is considered as the true or ideal input-output characteristics. It has been observed that most sensors are typically either nonlinear or linear over alimited range of interest only. Even sensors that produce approximately linear outputs may cause problems when precise measurements of the signalare required. It is unrealistic to feed nonlinear sensor signals to linear devices like meters, plotters, actuators, etc., without linearization. Strictly speaking, here a sensor does not mean the sensing device alone, but includes the complete signal conditioning system comprising the amplier, lter, analog-to-digitalconverter (ADC), etc. Therefore, the nonlinearity of asensor may also be resulted from the nonlinearity of the amplier, lter, ADC, etc. The nonlinearity of asensor circuit is resulted from nonlinearity of devices like metal-oxide semiconductor (MOS)-channel resistors, gate capacitor, etc. Operational ampliers also show limited gain and pass band due to which measurement systems suffers from the problem of nonlinearity.
