TUNABLE BAND NOTCH FILTER Russian patent published in 2022 - IPC H03H11/04 

FIELD: radio engineering.

SUBSTANCE: invention relates to the field of radio engineering and can be used to suppress unwanted signals (interference) in communication and radar systems, incl. in the functional units of power amplifiers. In particular cases, digitally controlled resistors or digital potentiometers can be used as these auxiliary resistors. A notch filter with a tunable bandwidth contains an input (1) and an output (2) of the device, a terminating resistor (3), a series LC oscillatory circuit (4) with the first (5) and second (6) outputs, including a frequency-setting capacitor (7) and inductance (8), wherein the first output of the terminating resistor (3) is connected to the input (1) of the device, and its second output is connected to the output of the device (2) and is connected to the first output (5) of the series LC oscillatory circuit (4). The second output of the terminating resistor (3) is connected to the output of the device (2) through the first (9) buffer amplifier, the output (2) of the device is connected through an additional voltage divider (10) to the input of the second (11) buffer amplifier, the output of which is connected to the second output (6) series LC oscillating circuit (4).

EFFECT: creation of a notch filter, which provides for bandwidth adjustment not by changing the parameters of the frequency-setting inductance 8 or capacitor 7, but by controlling the resistance of auxiliary resistors.

2 cl, 4 dwg