An analysis of high frequency transistor mixers

This report presents the results of a study of transistor mixer operation at high frequencies. A general analysis of mixer operation is developed based on the assumption that any device in which mixing occurs can be represented by a linear network with time varying components. From this analysis a general mixer equivalent circuit is developed. This may be applied in the transistor mixer case by proper modification of the Giacolletto equivalent circuit. In the theoretical analysis it is assumed that collector current can be represented by a square wave switched at the local oscillator frequency. In actual practice IC does not approach a square wave sufficiently for good agreement with experimental results. A constant correction factor is experimentally determined which when included in the equation allows calculation of conversion gains that agree to within 5% to 10% of those measured.