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Transistor Diode Clamping and Biasing Circuit

IP.com Disclosure Number: IPCOM000077657D
Original Publication Date: 1972-Sep-01
Included in the Prior Art Database: 2005-Feb-25
Document File: 2 page(s) / 28K

Publishing Venue

IBM

Related People

Chang, AW: AUTHOR

Abstract

A Schottky barrier diode D1 connected across the base-to-collector terminals of multiemitter transistor T1, provides a larger voltage threshold and thus is capable of clamping collector voltages in conventional current-switch logic family, and is also capable of being employed as a constant-voltage reference source.

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Transistor Diode Clamping and Biasing Circuit

A Schottky barrier diode D1 connected across the base-to-collector terminals of multiemitter transistor T1, provides a larger voltage threshold and thus is capable of clamping collector voltages in conventional current-switch logic family, and is also capable of being employed as a constant-voltage reference source.

The circuit comprises an input transistor T2 capable of receiving a logic signal on its base terminal 10. The collector of T2 is connected to a power supply V1 by way of resistor R1, and also to one of the emitter terminals of T1. The emitter terminal of T2 is connected to a current source I which in turn is connected to a voltage source V2. A second input switching transistor T4 is adapted to receive a logic signal at its base terminal 12. The collector of T4 is connected to the supply V1 via resistor R2 and is also connected to the other emitter terminal of T1. The emitter of T4 is connected to the current source I.

When T1 is conducting the diode D1 is only subjected to the base current associated with T1. Accordingly, current fluctuations at the r terminals of T1 are reduced by a factor of beta and regulated by the forward characteristics of the diode D1. Accordingly, very stable clamping levels can be achieved over a wide range of current, which allows the circuit to be advantageously implemented by collector dotting techniques. Moreover, this stability allows many emitter diffusions to be placed in a...