| 摘要 |
PURPOSE: A circuit for canceling a DC offset is provided to prevent the characteristic degradation of a receiver by canceling the DC offset using a feedback loop path and minimizing the interference influence in a desired signal band. CONSTITUTION: A BPF(Band Pass Filter)(220) receives an RF(Radio Frequency) signal, and cancels a noise signal except for a receiving band signal. An AGC(Automatic Gain Control) amplifier(230) varies a gain according to the strength of a demodulation signal, and amplifies the output signal of the BPF(220). Mixers(241,242) convert the output signal of the AGC amplifier(230) into a baseband signal having 90° phase difference. DC offset compensating units(250,260) cancel a DC offset through a feedback loop for comparing the output signals of the mixers(241,242) with a reference value, digitally process two signals in which the DC offset is cancelled, and output demodulation signals.
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