In this topology, the differential input voltage is imposed on the input resistor, producing an output current that passes through the load resistor. The gain equals to the ratio between the load resistor and the input resistor. The main advantage of this topology is that the input bias current is decoupled from common-mode input voltage and is relatively constant. Unlike the diff amp topology where the common-mode voltage has direct resistive paths to ground through the gain setting resistors, the common-mode impedance can be very high. The only source for bias current is the input bias current of the op amp.

Figure 4-2 shows several variations of the current feedback topology. To the left is a basic form which is unidirectional and only works when the differential input voltage is positive. The basic form also has common-mode limitations and will not function near ground. To the right is a variation where an output buffer is integrated to provide an output voltage, and avoid loading by downstream circuitry. In the middle is a variation adapted from the basic form to accommodate bidirectional current sensing. A second input amplifier is integrated thereby extending the input common-mode range to include ground and negative voltages.