Browse Prior Art Database

Current Switch

IP.com Disclosure Number: IPCOM000098125D
Original Publication Date: 1960-Feb-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 25K

Publishing Venue

IBM

Related People

Wortzman, D: AUTHOR

Abstract

The switching circuit provides a constant current output with very small tolerances, in the order of +- 0. 1% suitable for use in digital to analog converters.

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Current Switch

The switching circuit provides a constant current output with very small tolerances, in the order of +- 0. 1% suitable for use in digital to analog converters.

A logic signal at terminal 1 is effective to divert all the current generated by the V+ source through resistor 3, from transistor 4 to transistor 5. For a perfect switch, this current should appear at terminal 2. A certain amount of the current appearing at the emitter 6 of transistor 5 is diverted through the base 7 decreasing the output current. The base current lost is combined with a current through resistor 8 at the emitter 9 of transistor 10. A portion of this combined current is lost at the base 11 of transistor 10, but the collector current of transistor 10 substantially restores the base current lost from transistor 5 at the output terminal 2.

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