A subharmonic mixer circuit having an input stage (52) and a current modulating stage (64) is disclosed. The input stage (52) receives an RF input signal (RF+, RF−) at a first frequency and generates output currents (i1, i2) varying in dependence upon the Rf input signal. The current modulating stage (64) comprises a first transistor (Q3) for receiving a first local oscillator signal (LOO) respective and a second transistor (Q4) for receiving a second local oscillator signal (LOI 80), 180 degrees out of phase with the first local oscillator signal, such that a modulating current signal (i0), having twice the local oscillator frequency, is superimposed onto the output currents.