DC offset voltage reduction in cascaded instrumentation amplifier

Operational amplifiers (op-amps) are the building blocks for all analog signal conditioning circuits and also in particular, instrumentation amplifiers (INAs). The op-amp is a differential amplifier (DA), allow us to not only amplify very small signals of sensor but also to add or subtract offset voltages and to electrically isolate (buffer) sensors from the rest of system. In this paper, we present the amplification of Yokto level signal (10^-24V) to the saturation level of op-amp with the help of cascaded structure of INA. We can say, this is the cascaded INA. This structure of INA with order five, amplifies the signal level up to 490dB at normal condition of components. But at the critical values of all the components, the gain will be improved by approximately 630dB [1]. The gain level is also increased with increment in the order of the INA. Practically, due to the offset voltage, very high gain and number of stages; cascaded INA gives the +ve or -ve saturation or clipped output voltage. Therefore, In this paper, we presents the modified structure of cascaded INA for the reduction of output offset voltage and cascaded INA efficiently works.