| 摘要 |
<p>Pseudo-noise (PN) carrier suppression up-converter and pseudo-noise image sideband rejection up-converter and down-converter circuits are provided. The image sideband rejection circuits enable the use of single step up-conversion without the need for the high Q filters associated with two-step up-conversion architectures. For carrier suppression, the frequency spectrum of an input signal is PSK (BPSK or QPSK) spread by a PN signal and the spread signal is up-converted using a PSK (BPSK or QPSK) modulated carrier (local oscillator) modulated by the same PN sequence. In an up-converter, a carrier is QPSK modulated using independent PN sequences and the frequency spectrum of the input signal is QPSK spread using the same independent PN sequences whereby image sideband rejection results upon up-converting the QPSK spread signal in a mixer using the QPSK modulated carrier. In a down-converter, a carrier signal which is QPSK modulated by independent PN sequences is used to down-convert an input signal in a mixer and the resulting down-converted signal is QPSK spread using the same independent PN sequences whereby image sideband rejection occurs.</p> |
