US 12,034,367 B2
Switching power converter and active EMI filter circuit thereof
Chen-Pin Huang, Taoyuan (TW); Chia-Chun Li, Yunlin (TW); Chen-Lin Hsu, Taoyuan (TW); Hung-Yu Cheng, Taipei (TW); and Wan-Hsuan Yang, Hsinchu (TW)
Assigned to RICHTEK TECHNOLOGY CORPORATION, Zhubei (TW)
Filed by Richtek Technology Corporation, Zhubei (TW)
Filed on Jun. 27, 2022, as Appl. No. 17/851,015.
Claims priority of provisional application 63/215,591, filed on Jun. 28, 2021.
Prior Publication US 2022/0416652 A1, Dec. 29, 2022
Int. Cl. H02M 3/158 (2006.01); H02M 1/00 (2006.01); H02M 1/34 (2007.01); H02M 1/44 (2007.01)
CPC H02M 1/44 (2013.01) [H02M 1/0009 (2021.05); H02M 1/34 (2013.01); H02M 3/158 (2013.01)] 2 Claims
OG exemplary drawing
 
1. A switching power converter comprising:
a power stage circuit, including at least one transistor, configured to operably switch an inductor to convert an input power to an output power;
a switching controller, configured to operably control the at least one switch;
an AEF (Active EMI Filter) circuit, including at least one amplifier, wherein the at least one amplifier is configured to operably sense a noise input signal which is related to a switching noise caused by the switching of the power stage circuit, and amplify the noise input signal to generate a noise cancelling signal, wherein the noise cancelling signal is injected into an input node of the switching power converter, so as to suppress the switching noise and thus reducing EMI, wherein the input power is provided through the input node to the power stage circuit;
a sensing resistor, wherein a first terminal of the sensing resistor is directly connected to the input node, and a second terminal of the sensing resistor is coupled to the power stage circuit, wherein the noise input signal is generated according to a voltage across the sensing resistor; and
a passive filter circuit, wherein the passive filter circuit is directly connected between the sensing resistor and the power stage circuit, wherein the passive filter circuit includes a filtering inductor and a filtering capacitor for further filtering the noise input signal;
wherein the at least one amplifier includes an amplifier, wherein an inverting input terminal of the amplifier is coupled to the second terminal of the sensing resistor through a first input capacitor, and a non-inverting input terminal of the amplifier is coupled to the first terminal of the sensing resistor through a second input capacitor, such that an AC (alternating current) component of the noise input signal are differentially coupled from the sensing resistor;
wherein the noise cancelling signal is generated from an output terminal of the amplifier, wherein the noise cancelling signal is coupled to the first terminal of the sensing resistor through an injection capacitor, such that an AC component of the noise cancelling signal is injected into the input node of the switching power converter; and
wherein the AEF circuit further includes a first input resistor and a second input resistor which are coupled in series with the first input capacitor and the second input capacitor respectively.