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US 4,048,647 AGranted
Solid state disconnect device
AssigneeNorthern Telecom Limited
InventorKenneth Arnold Pickar
Life of this patent
Estimating the term…
Abstract
A solid state disconnect or isolating device for disconnecting a subscriber on his premises, replaces a relay with associated circuitry and items. It can be coupled with a surge protection device to provide disconnect signalling, plus loop testing if desired. The device comprises a normally "on" junction field effect transistor which acts as a pinch resistor.
Claims6
A solid state disconnect device for a telecommunication system including a Tip line and a Ring line, comprising:
- a pinch resistor element in each of said lines, each pinch resistor element including source, drain and gate areas, means connecting said lines to respective source and drain areas to connect said pinch resistor elements in said lines, an element in each line, each resistor element further including a substrate contact;
- means for electrically connecting said substrate to said gate area of each resistor element, means for electrically connecting the gate area of each resistor element to the line in which is connected the other resistor element, and a termination device electrically connected between said gate areas of said elements;
- the arrangement such that application of a suitable voltage on one of said lines with respect to the other of said lines disconnects said other of said lines and connects said termination device.
Dependencies are inferred from the claim text.