Drive circuit with limited signal transition rate for RFI reduction
US4739193A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Oct 30, 1986 |
| Grant date | Apr 19, 1988 |
| Priority date | — |
| Expiry date | Oct 30, 2006 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03K19/00361
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
An amplifier applies turn-on bias to the gate electrode of an output field-effect transistor in response to a first level of an input signal applied to the amplifier. A switched power source supplies operating current to the amplifier for developing the turn-on bias when the amplifier input signal is at the first level. A feedback-controlled bypass circuit diverts a portion of the operating current from the amplifier during an initial turn-on period and gradually reduces the magnitude of the diverted operating current as the output transistor turns on thereby producing a "soft" turn-on of the output transistor so as to minimize a potential for creating radio frequency interference in nearby RFI sensitive devices such as the tuner in a television or radio receiver. Complementary circuits include dual current supply and diversion circuits providing controlled rise and fall times for complementary field-effect output transistors.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.