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High Speed Operating Switch Disclosure Number: IPCOM000088251D
Original Publication Date: 1977-May-01
Included in the Prior Art Database: 2005-Mar-04
Document File: 2 page(s) / 30K

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Related People

Flamien, G: AUTHOR


The drawing shows a switch which presents minimum turn on and turn off times.

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High Speed Operating Switch

The drawing shows a switch which presents minimum turn on and turn off times.

The switch comprises input transistor T1 and output transistor T3, and means for providing a high base current to transistor T3 at the beginning of its conduction while preventing transistor T3 from entering into saturation. This allows the switching time to be reduced.

When a signal having a level + Vcc is applied at input I of the switch, a current is provided to the base of transistor T3 through resistor R1, base-collector junction of transistor T1, resistors R2, R3 and diode-connected transistor T4. Consequently, transistor T3 conducts. At the time that the voltage across node A and the collector of T3 reaches the level at which the transistor T2 conducts, a part of the base current of T3 is shunted through transistor T2, Consequently, the base current of transistor T3 decreases, thus preventing the saturation of transistor T3.

Thus, transistor T3 will turn off very rapidly when a zero-volt level signal is applied to input I.


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