FOURTH ORDER BAND FILTER Russian patent published in 2021 - IPC H03H11/04 

FIELD: radio engineering.

SUBSTANCE: invention relates to radio engineering and communications and can be used as an interface to limit the spectrum of the signal source. The fourth-order bandpass filter contains the input (1) of the device connected to the signal source (2), the output (3) of the device connected to the load (4), the input bandpass filter of the second order with the first (5) and second (6) inputs, and also the main output (7), the inverting input of the first (8) operational amplifier, the first (9) resistor, the second (10) resistor, the second (11) operational amplifier, third (12) resistor, first (13) capacitor, common bus of power supplies (14), third (15) operational amplifier, fourth (16) and fifth (17) resistors, sixth (18) resistor, fourth (19) operational amplifier, the second (20) capacitor, the seventh - eleventh (21-25) resistors. An output band-pass filter (26) is introduced into the circuit of the device, which is identical to the input band-pass filter in terms of the composition of elements, connections between them and the functional purpose of inputs and outputs, containing the first (27) (in.1*) and the second (28) (in.2*) inputs, as well as the main output (29) (out.1*), an additional input adder (30), the first (31) input of an additional input adder (30), the second (32) input of an additional input adder (30).

EFFECT: creation of conditions under which a bandpass filter of the fourth order has the ability to change the bandwidth and has an extended frequency range.

2 cl, 6 dwg