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Diode or For Current Switching Circuits

IP.com Disclosure Number: IPCOM000098213D
Original Publication Date: 1960-Apr-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 22K

Publishing Venue

IBM

Related People

McKendry, FJ: AUTHOR

Abstract

The diode circuit shown performs a logical OR function with a marked reduction in the number of OR transistors required and with substantially less rise time delays. In the conventional transistor OR circuit, individual input signals are fed to the bases of individual transistors which are normally in the off state. In this circuit, OR transistors are eliminated and the input signals are fed directly into a diode. There is substantially less rise time because there is no need to turn on normally cut off OR transistors and also because the NPN driver is not fully cut off. The circuit operates in the following manner.

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Diode or For Current Switching Circuits

The diode circuit shown performs a logical OR function with a marked reduction in the number of OR transistors required and with substantially less rise time delays. In the conventional transistor OR circuit, individual input signals are fed to the bases of individual transistors which are normally in the off state. In this circuit, OR transistors are eliminated and the input signals are fed directly into a diode. There is substantially less rise time because there is no need to turn on normally cut off OR transistors and also because the NPN driver is not fully cut off. The circuit operates in the following manner.

With the input +An circuits drawing no current, 6 ma. of current flows through NPN to the -12 v. source and the emitter of the NPN is at -6.2 v. The 6 ma. current flow places the output level of the N line at -1 v. With one input +An circuit drawing current from the OR, a 6 ma. current flow is supplied by the -12 v. supply and the emitter of NPN remains at -6.2 v. However, since the -12 v. supply only delivers a maximum current of 6 ma., the current through NPN to the output network goes to zero or near zero and the output level rises to +.8 v. With more than one +An up at the same time, the -12 v. supply still supplies its maximum current of 6 ma. and all additional current required by the OR input will be supplied by the -6 v. supply and diode F. Hence, the current to the output network is still substantially...