Patent ID: 7684777

Claim:
An adjacent channel rejection device for a receiving apparatus, which receiving apparatus comprises a quadrature mixer for mixing an analog radio-frequency signal on a desired channel with a local oscillator signal to in-phase and quadrature signal components at an intermediate frequency, a polyphase filter for band pass filtering said in-phase and quadrature signal components, and an analog-to-digital converter for converting said in-phase and quadrature signal components into digital form, and in which adjacent channel interference may occur due to in-phase and quadrature signal component mismatching in said quadrature mixer, comprising: an input for receiving said in-phase and quadrature signal components at said intermediate frequency before being band pass filtered by said polyphase filter, an analog compensation circuit device for compensating for said in-phase and quadrature signal component mismatching in said quadrature mixer responsive to one or more predetermined digital control signals input to said analog compensation circuit device by compensating one of said in-phase and quadrature signal components relative to the other one of said in-phase and quadrature signal components, and an output for outputting towards said polyphase filter in-phase and quadrature signal components, after having compensated for said in-phase and quadrature signal component mismatching, wherein said analog compensation circuit device is provided for implementing the compensation equation I=K′((1+α)I′+βQ′), where I is the compensated in-phase signal component, I′ and Q′ are the distorted in-phase and quadrature signal components due to said in-phase and quadrature signal component mismatching, and K′, α and β are related to the amplitude and phase errors as introduced by said in-phase and quadrature signal component mismatching.