WIDE-BAND SWITCHED FILTER Russian patent published in 1997 - IPC

FIELD: input frequency- selective device of radio receiver, can also be used as an output frequency-selective device of a wide-band radio transmitter. SUBSTANCE: wide-band switched filter has N channels; each channel uses a band-pass filter made in the form of three-series-connected band-pass sections. The inputs of the first and outputs of the third band-pass sections of all channels are combined and serve as the input and output of the wide-band switched filter, respectively. In each band-pass filter the second band-pass section uses two parallel oscillatory circuits, and the first and third band-pass sections use an L-half-section at the input and output, respectively. All parallel oscillatory circuits of the second band-pass sections are series-connected to one another, and each point of connection of these circuits is connected to the common bus via the respective switching element; each leadout (except for the two ones connected to the common bus) of each parallel circuit is connected to the output or input of the respective L-half- sections via coupling capacitors; the tuning frequencies of the first and third band-pass sections in each band-pass filter are shifted relative to one another by the bandwidth of the band-pass filter. EFFECT: enhanced selectivity. 3 cl, 2 dwg