US 12,341,483 B2
Multistage active filter for automotive applications
Alessandro Amaducci, Deitingen (CH); and Enrico Mazzola, Gerlafingen (CH)
Assigned to Schaffner EMV AG, Luterbach (CH)
Filed by Schaffner EMV AG, Luterbach (CH)
Filed on Feb. 11, 2022, as Appl. No. 17/670,280.
Claims priority of application No. 21157191 (EP), filed on Feb. 15, 2021.
Prior Publication US 2022/0263496 A1, Aug. 18, 2022
Int. Cl. H03F 3/45 (2006.01); H03H 11/04 (2006.01); H03H 11/12 (2006.01)
CPC H03H 11/12 (2013.01) [H03H 11/04 (2013.01)] 8 Claims
OG exemplary drawing
 
1. An active filter for suppressing an unwanted noise component from an electric supply line connecting a noise source and a load device, the active filter comprising a first active filter and a second active filter on the supply line, wherein the first active filter is between the noise source and the second active filter, wherein the first active filter has a first attenuation, and the second active filter has a second attenuation, wherein the first attenuation is lower than the second attenuation, wherein the first active filter and the second active filter have each a current transformer configured to detect a noise current circulating on the supply line, a gain stage, generating a current correction signal, and an output stage configured to feed back the current correction signal in the supply line.