| 摘要 |
An apparatus for reducing undesirable low-frequency distortion in a direct conversion communication receiver includes a signal generator (26) to produce a first periodic signal and a second periodic signal. A merge circuit (24) combines an input signal and the first periodic signal to produce a modulated signal with a polarity switched component. A frequency translation circuit (22) converts the modulated signal into a baseband signal with a spectrum substantially equal to the modulated signal, but centered around a carrier frequency of approximately zero and including a low-frequency error component. An output modulator circuit (28) combines the baseband signal wherein the low-frequency error component is shifted to a high frequency spectrum position and the polarity switched component is eliminated. A low-pass filter subsequently removes the low-frequency error component from the modified baseband signal, resulting in a baseband output signal with reduced low-frequency distortion. |
