A sub-harmonic mixer two or more cascaded stages for converting a Radio Frequency signal to an Intermediate Frequency signal. Each stage comprises a common-emitter transistor or a common-source transistor and each stage having an input and an output, the output of each stage is coupled to the input of a next stage by a capacitor. An Alternating Current choke is coupled at a collector or drain of each transistor. An LO input is coupled to the input of a first stage of the two or more stages; an RF input is coupled to the output of the first stage of the two or more stages; and an IF output is coupled to the output of a last stage of the two or more stages.