LOW-FREQUENCIES FILTER WITH GALVANIC ISOLATION Russian patent published in 2019 - IPC H03H7/12 

FIELD: measuring equipment.

SUBSTANCE: invention relates to the low-frequency differential signals measurement against the common-mode voltages and high-power electromagnetic interference background in the wide frequency band using galvanic isolation. Filter contains the input TD, which non-inverting input is connected to the first resistor and the first capacitor, which second terminals are connected to the common bus, TD inverting input is connected to the second resistor and to the common bus through in-series connected the second resistor and the second capacitor and through the in-parallel connected the third resistor and the third capacitor is to its output, fourth resistor first output is connected to the TD non-inverting input; additionally introduced are the fifth, sixth, seventh, eighth, ninth, tenth resistors, and the fourth capacitor, which first output is connected to the common bus, and the second output is connected to the fourth resistor second output, through the ninth resistor is to the first input bus and to the tenth resistor first output, which second output is connected to the second input bus and through the in-parallel connected seventh and eighth resistors is to the second resistor second output, at that, through the fifth and sixth resistors, respectively, the TD inverting and non-inverting inputs are connected to the common bus. As the first and the third resistors the dual digital potentiometer can be used.

EFFECT: technical result consists in provision of the input resistance, the input signal from the common bus isolation resistance, input common-mode voltage, the voltage galvanic isolation for the given transfer coefficient high normalized values, as well as provision of the signal source resistance compensation, reducing the common-mode voltages suppression coefficient.

1 cl, 3 dwg