FOURTH-ORDER LOW-FREQUENCY FILTER Russian patent published in 2021 - IPC H03H11/12 

FIELD: radio engineering.
SUBSTANCE: invention relates to the field of radio engineering, as well as measuring equipment, for example, as spectrum limiters included at the input of analog-to-digital converters for various purposes. The low-frequency filter (hereinafter – LFF) contains input (1) of the device connected to signal source (2), output (3) of the device connected to load (4), the second-order input LFF, first operational amplifier (11), first (12), second (13) resistors, second operational amplifier (14), third resistor (15), first capacitor (16), fourth operational amplifier (20), second capacitor (21), fifth (22), sixth (23), seventh (24), eighth (25), ninth (27), tenth (28) resistors, common power supply bus (17), second-order output low-frequency filter (29), identical to the input low-frequency filter in terms of the composition of the elements, the connections between them and the functional purpose of the inputs and outputs, containing first (30) (in.1*) and second (31) (in.2*) inputs, as well as first (32) (out.1*), second (33) (out.2*), third (34) (out.3*) and fourth (35) (out.4*) outputs, additional inverting amplifier (36), additional inverting adder (37).

EFFECT: provision of the transfer function of the fourth-order low-frequency filter.

5 cl, 8 dwg