| 摘要 |
The invention concerns a band-pass filtering method which consists in carrying out in parallel two frequency transpositions of an input signal to be filtered (SE) using respectively a first upstream mixing signal (SM1) and a second substantially phase quadrature upstream mixing signal (SM2), so as to obtain respectively first (ST1) and second (ST2) transposed signals, and in filtering respectively the two transposed signals by two band-pass filters (F1, F2), the frequency of said transposition signals ( omega 0) and the bandwidths of the band-pass filters (B/2) being connected to the input signal ( omega e) and to the desired bandwidth for the band-pass filter; then in carrying out respective frequency transpositions on the first filtered transposed signal (STF1) and the second filtered transposed signal (STF2) by means of the two respective downstream mixing signals; and in subtracting or adding the two resulting signals, the frequency output mixing signals (SMV1, SMV2) being selected different from the frequency of the first and second mixing signals such that the output signal is transposed in a desired frequency interval. The invention is characterised in that it consists in using a common oscillator (LO) coupled with a first phase shifter (MTM) to produce the upstream mixing signals and coupled with a second phase shifter (MTV) to produce the downstream mixing signals.
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