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Nonlinear Resistor for Collector Clamping

IP.com Disclosure Number: IPCOM000094301D
Original Publication Date: 1966-Aug-01
Included in the Prior Art Database: 2005-Mar-06
Document File: 2 page(s) / 32K

Publishing Venue

IBM

Related People

Cavaliere, JR: AUTHOR

Abstract

This is a clamp circuit for preventing saturation of a group of commonly connected transistor circuits.

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Nonlinear Resistor for Collector Clamping

This is a clamp circuit for preventing saturation of a group of commonly connected transistor circuits.

Transistors T1 and T2 and their allied circuitry have their collectors connected in common to output conductor 0-1. Connected to the emitter of each of these transistors is a grounded-base transistor. The combination forms a current switch configuration. If transistors T1, T2, etc., are rendered simultaneously conductive, the potential on output conductor 0-1 can fall to a level which forward biases the respective collector-base junctions and thus saturates each transistor.

To prevent this from occurring, a clamp circuit which includes transistor T3 and shunt resistors R1 and R2 is provided. The current normally drawn through R1 and R2 is insufficient to bias T3 for conduction. When, however, and excessive amount of current begins to flow through R1 and R2 such as when T1 and T2 approach saturation, the potential at the base of T3 becomes sufficiently high to render it conductive. This action thus clamps the potential on output line 0-1 to a level set by the base-emitter diode of T3 and prevents any further potential fall.

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