| 摘要 |
A circuit ( 100 ) comprising an antenna ( 105 ) for receiving a carrier signal modulated by a data signal, a direct conversion receiver ( 180 ) for receiving the modulated carrier signal, a signal generator circuit ( 140, 145, 150 ) arranged to generate a mixing signal having a frequency substantially the same as the carrier signal, a mixing module ( 125 i, 125 q) having an in-phase and a quadrature phase signal path ( 120 i, 120 q) arranged to mix the mixing signal at different phases with the received modulated carrier signal in order to generate an in-phase and a quadrature baseband signal, a frequency offset circuit ( 155, 200 ) arranged to generate an offset signal having a frequency offset from the frequency of the carrier signal, a coupling circuit ( 170 a, 170 b, 170 c) 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.
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