US Patent 7929241 Signal conversion system and method

A signal conversion circuit includes: an input circuit that rejects common mode inputs and is configured to receive a differential input signal and shift a first bias of the differential input signal to produce a single ended intermediate signal with a second bias; and an amplifier circuit configured to amplify the single ended intermediate signal to produce an amplified signal. The input circuit can include: first and second transistors with drains configured to couple with a supply voltage, and gates of the first transistor and the second transistor are configured to receive the differential input signal; a first resistor coupled to a source of the first transistor and a drain of a third transistor; and a second resistor coupled to a source of the second transistor and a drain of a fourth transistor; where the third transistor and the fourth transistor are connected in a current mirror configuration.