Patent ID: 7860196
Filing Date: 2010-12-28
Classification: H04B

Abstract:
1. A circuit comprising: an antenna for receiving a carrier signal modulated by a data signal; a direct conversion receiver for receiving the modulated carrier signal, the direct conversion receiver including a mixing module having an in-phase and a quadrature phase signal path arranged to mix a mixing signal at different phases with the received modulated carrier signal in order to generate an in-phase and a quadrature baseband signal; a signal generator circuit arranged to generate the mixing signal having a frequency substantially the same as the carrier signal; a frequency offset circuit arranged to generate an offset signal having a frequency offset from the frequency of the carrier signal; and a coupling circuit arranged to selectively decouple the antenna from the direct conversion receiver and to couple the offset signal to the mixing module in order to generate a baseband test signal in the in-phase and quadrature signal paths for determining an imbalance in the amplitudes of the baseband test signals between the in-phase and quadrature signal paths, wherein the signal generator circuit comprises a first frequency divider coupled to an oscillator the frequency offset circuit comprises a programmable frequency divider coupled to the oscillator, the programmable frequency divider having a division ratio offset from the division ratio of the first frequency divider in order to generate the offset signal, and at least one of: