Patent ID: 7117714

Claim:
An output amplifier circuit comprising: an offset voltage adjustment circuit for outputting a desired offset voltage adjusted according to an external instruction; a first input terminal for receiving a first electrode voltage of a differential output voltage; a second input terminal for receiving a second electrode voltage of the differential output voltage; a first voltage input terminal for receiving the offset voltage; a second voltage input terminal for receiving a reference voltage of an instrumentation amplifier output; and an instrumentation amplifier for amplifying the differential output voltage received through the first and second input terminals to output an amplifier circuit output voltage, wherein the instrumentation amplifier includes: a first operational amplifier having a non-inverting input connected to the first input terminal and an inverting input connected to the first voltage input terminal via a resistor; a second operational amplifier having a non-inverting input connected to the second input terminal and an inverting input connected to the second voltage input terminal via a resistor; and a third operational amplifier having a non-inverting input, connected to an output of the first operational amplifier and the second voltage input terminal via resistors, and an inverting input connected to an output of the second operational amplifier via a resistor, the third operational amplifier outputting the amplifier circuit output voltage through an output of the third operational amplifier.