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Current Switch Emitter Follower with Feedback

IP.com Disclosure Number: IPCOM000090443D
Original Publication Date: 1969-Apr-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 26K

Publishing Venue

IBM

Related People

Cavaliere, JR: AUTHOR

Abstract

The use of a double-emitter transistor in conventional current switch emitter-follower logic circuits provides improved operation and decreased switching times by utilizing negative feedback to improve static noise tolerance. Input terminals 10 and 12 connect to the bases of respective input switching transistors 14 and 16. Out-of-phase signals from the collectors of transistors 14 and 16 are connected to the base of double-emitter follower output transistor 18. Emitter 20 is connected to transistor 22 for providing a reference voltage to it. Emitter 24 is connected to output terminal 26 in order to provide an emitter-follower output signal in response to the input signal at the base of transistor 18. Appropriate biasing resistors R ...R and only source -V provide operating potential to the circuit.

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Current Switch Emitter Follower with Feedback

The use of a double-emitter transistor in conventional current switch emitter- follower logic circuits provides improved operation and decreased switching times by utilizing negative feedback to improve static noise tolerance. Input terminals 10 and 12 connect to the bases of respective input switching transistors 14 and 16. Out-of-phase signals from the collectors of transistors 14 and 16 are connected to the base of double-emitter follower output transistor 18. Emitter 20 is connected to transistor 22 for providing a reference voltage to it. Emitter 24 is connected to output terminal 26 in order to provide an emitter-follower output signal in response to the input signal at the base of transistor 18. Appropriate biasing resistors R ...R and only source -V provide operating potential to the circuit. In a Nor logic mode of operation, transistor 18 provides a reference level voltage for transistor 22. The voltage reference level at the collectors of transistors 14 and 16 is transmitted by the emitter 20 in order to establish a voltage reference level at the base of diode-transistor 22. With either input terminal 10 or 12 in an up state, transistors 14 and 16 conduct in order to transmit a down level to output level 26 via the emitter-follower output terminal
24. Transistors 14 and 16 are rapidly switched off when their respective terminals 10 or 12 are brought to a down level since a current path is provided through tr...