In a receiving apparatus comprising a quadrature mixer (5) for mixing a radio-frequency signal with a local oscillator signal to in-phase (I) and quadrature (Q) signal components at an intermediate frequency, a polyphase filter (9) for band pass filtering the IQ signal components, and an analog-to-digital converter (13) for converting the IQ signal components into digital form, and in which receiving apparatus adjacent channel interference may occur due to IQ signal component mismatching in the quadrature mixer (5), there is provided an adjacent channel rejection device connected between the quadrature mixer (5) and the polyphase filter (9). The device comprises an analog compensation circuit (33a; 33b; 33a-b) for compensating for the IQ signal component mismatching.