Remote as signal attenuator
US4937466A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 29, 1988 |
| Grant date | Jun 26, 1990 |
| Priority date | — |
| Expiry date | Sep 29, 2008 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03H11/245
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
The present disclosure provides a variable attenuator for attenuating alternating signals, preferably, in a frequency band extending from approximately 10 Hz to 30 MHz. The invention utilizes a junction field-effect transistor (JFET) as a variable impedance. The low drain-to-source capacitance exhibited by the JFET allows it to be modeled as a variable resistor or potentiometer. Further, the low drain-to-source capacitance of the JFET improves the bandwidth of the attenuator. A remote DC control signal defines the resistance provided by the JFET. A feedback loop, responsive to the resistance of the JFET and the remote control signal, controls the resistance provided by the JFET in a linear manner. The DC control signal is low-pass filtered at the feedback loop to reduce any high frequency noise acquired during transmission.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.