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# Logical Circuit

IP.com Disclosure Number: IPCOM000097621D
Original Publication Date: 1961-Mar-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 31K

IBM

## Related People

Mayeda, W: AUTHOR

## Abstract

An Esaki diode logical circuit used to obtain the negation function is shown at the left. A pair of Esaki diodes and a resistor R are connected in series between a positive supply voltage V(s) and ground. The input is applied to point P and the output is taken across the resistor R. The V-I characteristics for E1 and E2 (middle drawing) are such that I(max) for diode E1 is higher than I(max) for diode E2. Also, the high voltage regions of the respective diodes are different. Because of these differences, when the supply voltage V(s) rises to a value V(2) such that one diode changes to its high voltage state, the diode which does change its state is E2.

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Logical Circuit

An Esaki diode logical circuit used to obtain the negation function is shown at the left. A pair of Esaki diodes and a resistor R are connected in series between a positive supply voltage V(s) and ground. The input is applied to point P and the output is taken across the resistor R. The V-I characteristics for E1 and E2 (middle drawing) are such that I(max) for diode E1 is higher than I(max) for diode E2. Also, the high voltage regions of the respective diodes are different. Because of these differences, when the supply voltage V(s) rises to a value V(2) such that one diode changes to its high voltage state, the diode which does change its state is E2. With the load line illustrated and ignoring the voltage across the unswitched diode, when E2 switches to its high voltage state there will be a relatively large voltage equal to V2-V' across resistor R. When, however, the input voltage V(in) is large, E1 rather than E2 reaches its I(max) first and, hence, switches to the high voltage state. In this case, the output voltage V(0) is equal to V2-V which is a very small value. Hence, the negation function is realized by the left hand circuit.

A similar result is obtained by the right hand circuit. With this, however, E1 is chosen to have a lower I(max) than E2. In this case, with a low voltage input, the output voltage V(0) is equal to V and with a high voltage input, V(0) is equal to V'. By interchanging the locations of E1 and E2 and again with I(max)...