Abstract: An image rejection mixer circuit comprises a pair of mixers (1, 2) to which are supplied input signals from an input terminal (9) and oscillation signals in mutual quadrature from an oscillator (11). The mixer output signals are combined in a combining means (19) to produce at its output (20, 21) a frequency-translated wanted signal free from frequency-translated image signals. The combining means comprises an acoustic surface wave filter and, in order to avoid the necessity of providing it with a pair of input transducers, with the consequent increase in the area of piezo-electric substrate that would entail, it is provided with a single input transducer of the four-phase or pseudo four-phase type.