FIELD: radio engineering and communications.;SUBSTANCE: invention relates to radio engineering and communications; it can be used as an interface for limiting the spectrum of a signal source, for example, during its further processing by analog-to-digital converters of various modifications. The filter contains device input (1) connected to signal source (2), device output (3) connected to load (4), second-order input bandpass filter, first operational amplifier (8), first resistor (9), second resistor (10), second operational amplifier (11), third resistor (12), first capacitor (13), common bus of power supply (14), third operational amplifier (15), fourth (16), fifth (17), sixth (18) resistors, fourth operational amplifier (19), second capacitor (20), seventh (21), eighth (22), ninth (23), tenth (24), eleventh (25) resistors. Signal source (2) and load (4) are coordinated to common bus of power supply (14). Output bandpass filter (26), identical to input bandpass filter in terms of the element composition, the connections between them and the functional purpose of the inputs and outputs, and auxiliary resistor (30) are introduced into the device circuit. First input (5) of second-order input bandpass filter and first input (27) (in.1*) of second-order output bandpass filter (26) are coordinated with common bus of power supply (14).;EFFECT: technical result is providing a fourth-order bandpass filter with the possibility to change the bandwidth in an extended frequency range.;1 cl, 4 dwg
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