6. Electronically Controllable Current-Mode Instrumentation Amplifiers

In this chapter, Current-Mode Instrumentation Amplifiers (CMIAs) with the capability of having an electronically controllable gain are discussed. These CMIAs do not require variable passive resistors to change gain but the latter is adjusted by means of a control voltage or current. This kind of instrumentation amplifiers is more suitable for IC realization. We divide electronically controllable CMIAs into two categories. In the first category, gain is varied by means of either bias current or bias voltage of the used active building blocks. Here, electronic controllability is achieved at the expense of higher power consumption. In the second category, gain is varied by means of an electronically variable active resistor. Therefore, they have much simpler design and show less power consumption.