Browse Prior Art Database

Low Voltage T/2/L Circuit

IP.com Disclosure Number: IPCOM000076432D
Original Publication Date: 1972-Mar-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 2 page(s) / 28K

Publishing Venue

IBM

Related People

Johnson, KP: AUTHOR [+2]

Abstract

A pair of Schottky barrier diodes SBD1, SBD2 and R2 are added to a conventional transistor transistor logic (T/2/L) circuit, comprising multi-emitter input transistor TX1 and output transistor TX2, and a pair of resistors R1 and R3. The diodes SBD1 and SBD2 prevent transistors TX1 and TX2 from saturating. The addition of resistor R2 enhances low-voltage circuit operation.

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Low Voltage T/2/L Circuit

A pair of Schottky barrier diodes SBD1, SBD2 and R2 are added to a conventional transistor transistor logic (T/2/L) circuit, comprising multi-emitter input transistor TX1 and output transistor TX2, and a pair of resistors R1 and R3. The diodes SBD1 and SBD2 prevent transistors TX1 and TX2 from saturating. The addition of resistor R2 enhances low-voltage circuit operation.

In the conventional T/2/L circuit when the input is negative, current is drawn through the emitter of TX1 and R1. In the present circuit, input current is drawn through TX1 and R2. Thus the necessity of having a large voltage drop across R1 is eliminated. Further, in the conventional T/2/L circuit when the output is negative, base current for TX2 is supplied through R1 and the collector-base junction of TX1. In the present circuit base current can flow through R2. Also collector current for TX2 is allowed to flow through R2 and Schottky barrier diode SBD2.

Thus for both states of the circuit, current flows through R2 and node A acts as a point of current switching. In contradistinction, this function is served by node B in the conventional T/2/L circuit. For the two states of the circuit current flows through R2 and either through the collector of TX1, or into the Schottky barrier diodes SBD2 and the collector of TX2. This characteristic further prohibits the voltage at node A from changing significantly when switching between the two states, as contrasted with the conv...