Abstract: Apparatus for reducing the effects of mixer leakage in a zero IF transmission system includes first and second mixers having relatively equal leakage amounts from an oscillator port to an input port, with the input port of said first mixer adapted to receive a zero IF receiver input signal and with the output port of said first mixer capacitively coupled to the input port of the second mixer. The oscillator ports of the first and second mixers are coupled to a local oscillator output, with the output ports of said first and second mixers coupled respectively to an adder and subtractor circuit to provide respectively a DC signal indicative of the leakage and an output signal indicative of the magnitude of said input signal as effected by leakage to thereby enable the determination of said input signal after mixing.