A MOS analog mixer using a cross-coupled pair with source followers

A low-voltage MOS analog mixer using a cross-coupled pair as the core is described. The mixing operation is based on the square-law characteristic of the MOS transistor in the saturation region. Both theory and simulation show that the mixing characteristic is superior and not sensitive to device mismatches. The proposed mixer has a -3 dB frequency of 135 MHz and consumes 2 mW power. The nonlinearities of the mixer are less than 0.33% and 0.43%, and the THD is about 0.32% and 0.51%, with 0% and 5% device mismatch, respectively.