A linear amplifier that comprises a signal input terminal that receives an input signal having a first common mode voltage, a voltage amplifier having a non-inverting input terminal that receives a second common mode voltage, a first and a second input resistance connected in series from the signal input terminal to the inverting input terminal of the voltage amplifier, a feedback resistance connected between the inverting input terminal and the output terminal of the voltage amplifier, and a constant current source. The constant current source supplies a constant current to a middle node between the first and the second input resistances. The constant current generates a voltage drop, which is equal to a difference between the first and the second common mode voltages, across the first input resistance. Accordingly, the common mode voltage of the output signal is directly determined by the second common mode voltage.