Patent ID: 7183848

Claim:
A transconductance amplifier comprising: a first input circuit having a first feedback loop; a second input circuit having a second feedback loop; a resistor having a first interface connected to the first input circuit and a second interface connected to the second input circuit; a first differential pair having a first transistor arranged to control current flow in the first feedback loop to maintain a voltage at the first interface of the resistor at substantially a constant voltage relative to an input voltage applied to the first input circuit; a second transistor arranged to control current flow for a first output and a fifth transistor; and a second differential pair having a third transistor arranged to control current flow in the second feedback loop to maintain a voltage at the second interface of the resistor at substantially a constant voltage relative to an input voltage applied to the second input circuit, a fourth transistor arranged to control current flow for a second output and a sixth transistor, wherein the fifth transistor and sixth transistor are arranged to be coupled to a control signal for varying the current flow for the first output and the current flow for the second output respectively.