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Browse Prior Art Database

DC Driver Feedback Circuit

IP.com Disclosure Number: IPCOM000092497D
Original Publication Date: 1966-Nov-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 32K

Publishing Venue

IBM

Related People

Schumacher, RA: AUTHOR

Abstract

The circuit receives a signal at its input terminal 2 and produces a regulated current output on line 3. The circuit is particularly useful for driving magnetic memory elements with a preselected current amplitude. The circuit also provides a regulated voltage at output terminal 4.

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DC Driver Feedback Circuit

The circuit receives a signal at its input terminal 2 and produces a regulated current output on line 3. The circuit is particularly useful for driving magnetic memory elements with a preselected current amplitude. The circuit also provides a regulated voltage at output terminal 4.

The circuit includes two transistors T6 and T7 that are connected with resistor 8 in a current switch configuration. T7 has its base terminal connected to ground. One or the other of T6 and T7 conducts according to whether the voltage at input terminal 2 is above or below ground. The output at the collector terminal of T7 is amplified by two transistor stages having transistors T9 and T10. The latter has a resistor 11 in its emitter circuit. In this configuration, T10 conducts a current value that maintains the voltage across resistor 11 equal to the voltage at the collector terminal of T7 less the voltage drops across the base- emitter junctions of T9 and T10. A transistor T12 is connected in a feedback loop that tends to maintain this voltage and current constant.

The base of T12 is connected to point 4 where the voltage is regulated. The collector of T12 is connected to the common connection of the emitters of T6 and T7. This connection tends to vary the conduction of T7 in a way to oppose changes in voltage and current at point 4.

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