| 摘要 |
<p>PROBLEM TO BE SOLVED: To reduce the effect of a transmitter acting as interference. SOLUTION: A radio such as a frequency division duplex(FDD) radio (100) has a first local oscillator (LO1I and LO1Q) that is set to coincide with the center frequency or sub-harmonic of a transmitter section (126). In this way, after the first down-conversion, the transmit interfere is converted to DC, where it can be effectively removed using a simple high-pass filter (110 and 112) such as a DC blocking capacitor. Image rejection is achieved by the use of a two-step down-conversion approach that uses quadrature local oscillators to implement a signal-sideband down-converter.</p> |
