A circuit for measuring resistance of a magnetoresistive head. First and second current biasing circuits are respectively coupled to opposite sides of the head. The first biasing circuit includes a first resistance, and the second biasing circuit includes a second resistance. First and second current mirrors are respectively coupled to the first and second biasing circuits. A current leg is coupled to the current mirrors. The current mirrors drive current in the resistances so that a first voltage across the first resistance is substantially equal and opposite to a second voltage across the second resistance. The biasing circuits bias current through the head such that a voltage on the first side of the head is close to the first voltage and a voltage on the second side of the head is close to the second voltage, so that the common mode voltage of the head will be close to zero.