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High Speed Voltage Solid State Switching Circuit

IP.com Disclosure Number: IPCOM000078943D
Original Publication Date: 1973-Apr-01
Included in the Prior Art Database: 2005-Feb-26
Document File: 2 page(s) / 25K

Publishing Venue

IBM

Related People

Pavlovic, GF: AUTHOR

Abstract

By incorporating three solid state switches in the feedback loop of an operational amplifier, the ON resistance of the switch becomes a virtual zero resistance.

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High Speed Voltage Solid State Switching Circuit

By incorporating three solid state switches in the feedback loop of an operational amplifier, the ON resistance of the switch becomes a virtual zero resistance.

The three solid state switches are designated SSS #1, 2 and 3. In the ON state, switches 1 and 2 are energized. The load current 11 and the feedback current 12 flow through switch 1 creating a voltage drop. The feedback current I2 flows through switch 2. Since the feedback current is less than 10 microamps and the resistance of switch 2 is approximately 100 ohms, there is virtually no voltage drop across switch 2. At the summation of the amplifier, the voltage in the (+) input is equal to the voltage at the (-) input. With no voltage drop across switch 2, the voltage at node A will be equal to the voltage at the (+) input. In the OFF state, switch 3 is energized to maintain a closed-feedback loop for the amplifier. Switches 1 and 2 are not energized creating a virtual open circuit.

Previously, the ON resistance of a solid-state switch limited its utilization in switching circuits to low-current applications or in circuits where the current drain was known and could be compensated. By the present technique, these limitations are eliminated.

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