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Transistorized Analog Switch

IP.com Disclosure Number: IPCOM000094422D
Original Publication Date: 1965-Jan-01
Included in the Prior Art Database: 2005-Mar-06
Document File: 2 page(s) / 23K

Publishing Venue

IBM

Related People

Williams, LL: AUTHOR

Abstract

The circuit provides switching action between terminals A and B. When voltage sources V1 and V2 are activated with the polarity shown, the circuit between terminals A and B is closed. When sources V1 and V2 are deactivated there is an open circuit between terminals A and B.

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Transistorized Analog Switch

The circuit provides switching action between terminals A and B. When voltage sources V1 and V2 are activated with the polarity shown, the circuit between terminals A and B is closed. When sources V1 and V2 are deactivated there is an open circuit between terminals A and B.

Two transistors T1 and T2 are connected in series between terminals A and
B. Transistors T1 and T2 are connected in the inverted mode. The circuit also has two transistors T3 and T4 which interconnect the base and collector of each transistor. Sources V1 and V2 are connected to control transistors T3 and T4. Actuation of T3 and T4 by sources V1 and V2 switches T1 and T2. Two resistors R1 and R2 regulate the flow of current into the base of T1 and T2. Two resistors R3 and R4 supply base current to transistors T3 and T4.

This circuit has a low offset potential when closed and sustains a relatively high back voltage when open. The reason that the circuit has a low offset potential is that T1 and T2 are connected in the inverted mode. Thus, the offset potential due to one transistor is compensated by the offset potential of the second transistor. The reason that the circuit sustains a relatively high back voltage is that T3 and T4 open-circuit the base to collector paths.

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