VARIABLE LC-BAND-PASS FILTER Russian patent published in 2010 - IPC H03H7/75 H03H7/12 H03H19/00 

FIELD: physics.

SUBSTANCE: variable LC-band pass filter consists of n cascaded L-shaped half sections of high-pass filters, each having capacitors in a series circuit. The first lead of the capacitor is the first input of the half section and the second lead is the output which is connected to an inductor coil whose second output is connected to another capacitor. The input of the first half section is connected to the input potential terminal of the filter. The second leads of the capacitors which are connected in parallel circuits of the half sections are connected to a common bus. The output of the last half section is cascaded with m L-shaped half sections of low-pass filters, each consisting of an inductor coil and in a series circuit and a capacitor connected in parallel. The first leads of this inductor coil and the capacitor are the input of the half section and their second leads are the output which is connected to another capacitor. The output of the last half section is connected to the output potential terminal of the filter and the second leads of capacitors in the parallel circuit of the last ℓ half sections low-pass filters are connected to the common bus. k<n and ℓ<m are any integers. The invention is distinguished by that the filter has four groups of switches. The first group consists of n-k switches whose first leads are connected to input leads of half sections of the low-pass filter, starting with the k+1-th to the n-th half section respectively. Second leads of these switches are connected to the output of the high-pass filter. The second group consists of n-k switches whose first leads are connected to second leads of n-k capacitors connected in the parallel circuits of high-pass filters starting with the k+1-th half section to the n-th half section respectively. The second leads of these switches are connected to the common bus. The third group has m-ℓ switches whose first leads are connected to inputs of half sections of low-pass filters starting with the ℓ+1-th to the m-th, respectively. The first leads of these switches are connected to the output of the m-th half section. The fourth group consists of m-ℓ switches whose first leads are connected to second leads of m-ℓ capacitors connected in the parallel circuits of low-pass filters starting with the ℓ+1-th half section to the m-th half section, respectively. The second leads of these switches are connected to the common bus.

EFFECT: simplification.

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