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Voltage Comparator

IP.com Disclosure Number: IPCOM000097306D
Original Publication Date: 1962-Sep-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 28K

Publishing Venue

IBM

Related People

Salisbury, DE: AUTHOR

Abstract

This circuit provides a voltage output Vo on terminal 10 which follows reference voltage Vr on terminal 12. Voltage source Vs on terminal 14 is the source of energy for load resistance R1.

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Voltage Comparator

This circuit provides a voltage output Vo on terminal 10 which follows reference voltage Vr on terminal 12. Voltage source Vs on terminal 14 is the source of energy for load resistance R1.

In operation, when Vr starts to rise, the base potential of transistor Q2 is sufficient to permit it to conduct current. The current for regulation flows from Vs via transistors Q1, Q2 and Q3 and R1 to ground 16. The load current flows from Vs via Q1 and R1 to ground 16, establishing the output Vo across R1. When Vo approximates the value of Vr, Q3 starts to turn off which in turn causes Q2 to start turning off. As a result, there occurs a change of the base current of Q1 sufficient to maintain Vo at the voltage Vr magnitude. When Vr returns to ground level, Q2 turns off which turns off Q1. Output Vo returns to ground level.

If the load R1 changes in impedance during the operation, the current to it changes and Vs produces the necessary current to maintain the value of Vo equal to Vr.

If current regulation is desired, the load resistor RL is replaced by a precise standard resistor and resistance RL is connected between Vs and the emitter junction of Q1.

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