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Exclusive OR Invert Circuit

IP.com Disclosure Number: IPCOM000083561D
Original Publication Date: 1975-Jun-01
Included in the Prior Art Database: 2005-Mar-01
Document File: 2 page(s) / 37K

Publishing Venue

IBM

Related People

Debord, P: AUTHOR [+2]

Abstract

This exclusive OR circuit, using four bipolar transistors, works with very low-supply voltage.

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Exclusive OR Invert Circuit

This exclusive OR circuit, using four bipolar transistors, works with very low- supply voltage.

Transistors T1 and T2 are the two input transistors and transistors T3 and T4 perform the exclusive OR function. Diodes D1, D2, D3 and D4 are Schottky diodes avoiding the saturation of the transistors. Logic i puts A and B are applied to the bases of transistors T1 and T2, respectively. The output signal is generated at output node E.

If it is first assumed that logic inputs A and B are at a down logic level, T1 and T2 are nonconductive and nodes C and D have the same potential which is approximately VR. Transistors T3 and T4 are nonconductive and output node E is at the up logic level, which is approximately VR.

If logic inputs A and B are at an up logic level, T1 and T2 are conductive. The potential of nodes C and D are equivalent and consequently transistors T3 and T4 are nonconductive. Output node E is at the up logic level.

If logic input A is at a downlevel and logic input B at an uplevel, transistor T1 is nonconductive and transistor T2 is conductive. Node D is at a downlevel and node C at an uplevel. T3 is conductive but not T4 and output node E is at the down logic level. The same operation and case, that is output node E at a down logic level, exists if input A is at an uplevel and input B at a downlevel.

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