Patent ID: 7656601

Claim:
A circuit for measuring the resistance of a magnetoresistive head coupled to a current source, comprising: first and second current biasing circuits respectively coupled to first and second opposite sides of the magnetoresistive head for biasing current through the magnetoresistive head, wherein said first current biasing circuit includes a first resistance and said second current biasing circuit includes a second resistance, and wherein the first and second resistances have values substantially identical to each other and are both coupled to ground; first and second current mirrors respectively coupled to the first and second current biasing circuits; and a current leg coupled to the first and second current mirrors; wherein the current mirrors drive current in the first and second resistances so that a first voltage across the first resistance is substantially equal and opposite to a second voltage across the second resistance; and wherein the first and second current biasing circuits bias current through the magnetoresistive head such that a voltage on the first side of the magnetoresistive head is substantially close to the first voltage and such that a voltage on the second side of the magnetoresistive head is substantially close to the second voltage.