The situation is aggravated
when precise measurements are required and a linear relationship is
required between the process variable and the output signal. In analog circuits,
linearization is very hard to achieve and requires the use of specialized
networks. Figure 12.1a shows the output of a sensor when measuring a variable
and the idealized output obtained from a linearization circuit, with
adjustment of the gain and bias (zero level) as is required on many types of
sensor outputs.