Patent ID: 7263344

Claim:
A method of signal demodulation for a circuit having a differential transconductance input cell consisting of separate positive and negative channels for receiving positive and negative channels of said input signal x(t) and amplifying said positive and negative channels of said input signal x(t); a first differential mixer for receiving said amplified input signal x(t), and mixing said input signal x(t) with a first mixing signal φ 1 , to generate an output signal φ 1 x(t); a second differential mixer for receiving said signal φ 1 x(t) as an input, and mixing said signal φ 1 x(t) with a second mixing signal φ 2 , to generate an output signal φ 1 φ 2 x(t); a pair of current sources Ia and Ib for providing current to respective ones of said positive and negative channels of said differential transconductance input cell, to reduce the current drawn from said first differential mixer; said current sources Ia and Ib being trimmed in a complementary manner where Ia=I+ΔI, and Ib=I−ΔI; said method comprising the steps of: injecting a two-tone signal at said input; measuring IM2 at the baseband output of said circuit; determining the level of ΔI which minimizes IM2; recording the level of ΔI which minimizes IM2; and using said recorded level of ΔI during normal operation of said down-convertor.