Active filter for electromagnetic interference (EMI) reduction using a single connection point and a negative impedance converter
US11303264B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Nov 6, 2020 |
| Grant date | Apr 12, 2022 |
| Priority date | — |
| Expiry date | Nov 6, 2040 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03H1/0007
- 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 non-inverting input of an op amp to drive a power amplifier circuit through a filter capacitor. The power amplifier circuit increases the current drive of the op amp to charge a transfer capacitor that converts the power amplifier output current to a transfer voltage. The transfer capacitor is connected to the connection capacitor so that the transfer voltage is injected back into the power line through the connection capacitor as an injected voltage that compensates for the sensed current. Op amp gain is adjustable by variable resistors that connect to the inverting input of the op amp.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.