US 11,855,600 B2
High frequency, high output impedance amplifier for EMI active filter 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 Apr. 14, 2022, as Appl. No. 17/720,879.
Claims priority of application No. 21168429 (EP), filed on Apr. 14, 2021.
Prior Publication US 2022/0337226 A1, Oct. 20, 2022
Int. Cl. H03H 11/04 (2006.01); B60R 16/02 (2006.01); H03F 3/19 (2006.01)
CPC H03H 11/04 (2013.01) [B60R 16/02 (2013.01); H03F 3/19 (2013.01); H03F 2200/451 (2013.01)] 12 Claims
OG exemplary drawing
 
1. A high-frequency amplifier for an active EMI filter comprising a symmetric emitter-follower output stage for providing an output current with two bipolar transistors in a symmetric complementary pair configuration, an input stage driving the output stage, a sense resistor through which the output current flows, a voltage feedback loop for feeding back a voltage measured across the sense resistor to the input stage, wherein the high-frequency amplifier comprises a voltage reference defining a potential difference between bases of the bipolar transistors, wherein the voltage reference has a negative temperature coefficient.