Browse Prior Art Database

Current Source

IP.com Disclosure Number: IPCOM000075597D
Original Publication Date: 1971-Oct-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 2 page(s) / 23K

Publishing Venue

IBM

Related People

Platt, S: AUTHOR [+2]

Abstract

The drawing shows a circuit for producing a predetermined current at the collector terminal 2 of a transistor 3. Transistor 3 and an identical transistor 4 have their base terminals connected and their emitter terminals connected so that the two transistors conduct equally at their collector terminals, according to the current applied to the common connection point of the base terminals.

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Current Source

The drawing shows a circuit for producing a predetermined current at the collector terminal 2 of a transistor 3. Transistor 3 and an identical transistor 4 have their base terminals connected and their emitter terminals connected so that the two transistors conduct equally at their collector terminals, according to the current applied to the common connection point of the base terminals.

A resistor 5, connected in the collector circuit of transistor 4 establishes the current amplitude at point 2. A transistor 6 is connected to supply current to the base terminals of transistors 3 and 4, according to the current of resistor 5. Three series connected diodes 7, 8 and 9 are connected with a resistor 10 to produce a predetermined voltage drop across the series connection of resistor 5 and the emitter-to-collector circuit of transistor 4. The voltage across diode 7 equals the voltage across the base-emitter junction of transistor 4. Similarly, the voltage across diode 8 corresponds to the voltage across the base-emitter junction of transistor 6. Thus, the voltage across resistor 5 equals the voltage across diode 9. Transistor 6 operates to maintain this voltage relationship and to thereby maintain a fixed current at point 2.

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