Modified Maxwell-Wien bridge with auto source balance

This paper describes the realization of auto source balance in a modified Maxwell-Wien bridge by using a differential amplifier. The method of eliminating the oscillation of this differential amplifier is also discussed. The inductance measurement error introduced by the adoption of differential amplifier and related compensation circuit has also been analyzed in details. In the range of 100 μH∼100 H, the inductance measurement error caused by the amplifier is less than 2 ppm under 1 kHz .