Active filter for electromagnetic interference (EMI) reduction using a single connection point and a negative impedance converter with cross-coupled transistors
US11646720B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Feb 9, 2022 |
| Grant date | May 9, 2023 |
| Priority date | — |
| Expiry date | Feb 9, 2042 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03H2011/0483
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
An active filter reduces Electro-Magnetic Interference (EMI) created by current flowing through a power line. The active filter connects to the power line at a single node through a connection capacitor. A sense current flows through the connection capacitor when the power line current changes. This sense current is applied to a gain control circuit having cross-coupled PNP transistors that drive currents to both terminals of a variable capacitor. The variable capacitor converts these currents to a voltage that is injected back into the power line through the connection capacitor as an injected compensation voltage that compensates for the sensed current.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.