| 摘要 |
PURPOSE: A device for removing a DC(Direct Current) offset of a direct conversion receiver is provided to use a 90-degree phase shift, and to consist of 90-degree phase shifters, low pass filers, frequency mixers, and subtractors, thereby removing a DC offset. CONSTITUTION: An oscillator(200) generates a reference signal. The first phase shifter(210) phase-shifts the reference signal at 90 degrees. The first frequency mixer(212) mixes a receiving signal with the reference signal. The first low pass filer(214) low-filters an output signal of the first frequency mixer(212). The second phase shifter(220) phase-shifts the receiving signal at 90 degrees. The second frequency mixer(230) mixes an output signal of the first phase shifter(210) with an output signal of the second phase shifter(220). The second low pass filter(232) low-filters an output signal of the second frequency mixer(230). The first subtractor(240) subtracts an output signal of the first low pass filter(214) from an output signal of the second low pass filter(232).
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