An amplifying circuit comprises a bias circuit, a reference circuit, a first circuit, and an amplifying sub-circuit. The bias circuit is configured to provide a bias current. The reference circuit is configured to provide a first differential input based on a reference resistive device and a reference current derived from the bias current. The first circuit is configured to provide a second differential input based on a first current and a first resistance. The amplifying sub-circuit is configured to receive the first differential input and the second differential input and to generate a sense amplifying output indicative of a resistance relationship between the first resistance and a resistance of the reference resistive device.