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Schottky Barrier Diode Transmission Line Termination

IP.com Disclosure Number: IPCOM000087406D
Original Publication Date: 1977-Jan-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 2 page(s) / 28K

Publishing Venue

IBM

Related People

Householder, VR: AUTHOR

Abstract

In this circuit, a transistor 2 and associated components are connected to produce a pulse on a transmission line 3 in response to a digital signal at an input terminal 4. A transistor 5 and associated components are connected to receive the signal at an output 6 of transmission line 3 and to produce a related digital signal at circuit output 7.

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Schottky Barrier Diode Transmission Line Termination

In this circuit, a transistor 2 and associated components are connected to produce a pulse on a transmission line 3 in response to a digital signal at an input terminal 4. A transistor 5 and associated components are connected to receive the signal at an output 6 of transmission line 3 and to produce a related digital signal at circuit output 7.

In this transmission line circuit, there is a problem of a positive overshoot and a subsequent negative undershoot of the signal at point 6. Therefore, a clamp circuit is connected at point 6 to limit the positive overshoot and thereby prevent any subsequent negative undershoot. A conventional clamp comprises a diode 9 with its anode connected to point 6 and its cathode connected to a point of suitable reference voltage. When the voltage at point 6 exceeds the reference voltage plus the turn-on voltage of the diode, the diode turns on and conducts in circuit between point 6 and the reference voltage point to limit further voltage increase. When the voltage at which clamping occurs exceeds the voltage drop across a single diode, additional diodes can be connected in series. When the voltage is less than the voltage to turn on a conventional junction diode, the clamp can use a Schottky barrier diode which has a lower turn-on voltage.

A Schottky diode 9 and a transistor 10 are connected with a reference voltage point 11 to produce a low voltage drop, but to avoid the high...