Abstract: A transformer-coupled isolation amplifier which can accept signals over a wide dynamic range while maintaining very high linearity. An input signal is applied to an input winding of a transformer. The secondary winding of the isolation transformer is connected across the differential inputs of a high-gain amplifier. Negative feedback is provided around the amplifier so that the transformer secondary winding is connected across a virtual short; and the negative feedback tends to drive the voltage applied to the inputs of the amplifier to a very small value. The negative feedback from the amplifier induces a current in the transformer secondary which cancels the flux produced by current flowing in the primary, thereby reducing the effects of non-linearities in the BH curve of the transformer.