Phase Compensation of Voltage Follower

It is important to separate a useful signal from noise in measuring small voltage deviations of about 1 $\mu$ V and lower. This problem is relevant to eddy-current testing method in non-destructive testing metal constructions, thermal nondestructive testing, etc. The identification accuracy of a useful signal directly depends on the common-mode rejection ratio of subtraction circuit. The paper presents the circuit solutions concerning the increase in the common-mode rejection ratio using the power tracking with the phase error compensation of the voltage follower transfer factor and proposes a schematic circuit diagram of the phase compensated power tracking. The circuit was proposed for the phase compensated power tracking. The subtraction of two similar voltages of10 V on the PGA207 instrumentation amplifier could provide a 10 nV resolution at a frequency band up to 20 kHz.