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Differential Amplifier With Variable Output Voltage Bias

IP.com Disclosure Number: IPCOM000076443D
Original Publication Date: 1972-Mar-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 2 page(s) / 33K

Publishing Venue

IBM

Related People

Affinito, FJ: AUTHOR

Abstract

A pair of networks are employed, each including a potentiometer and current source arranged in the amplifier feedback loop. One current source acts to insert current to provide the desired output voltage bias, while the other current source acts to extract substantially all of the inserted current provided by the first source.

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Differential Amplifier With Variable Output Voltage Bias

A pair of networks are employed, each including a potentiometer and current source arranged in the amplifier feedback loop. One current source acts to insert current to provide the desired output voltage bias, while the other current source acts to extract substantially all of the inserted current provided by the first source.

Operational amplifier 1 receives, via resistors 3 and 5, a differential analog input signal E(CD) between its negative and positive input terminals C and D. Signal E(CD) is derived from analog signal E1. Signal E1 is applied between positive input terminal E, which is connected to one side of resistor 5, and negative input terminal F, which is connected to one side of resistor 3. The other side of resistor 5 is connected to ground, via resistor 7. Likewise, the other side of resistor 3 is connected to feedback loop 15. Signal E1 is the difference voltage between EB and EA, taken from sources 1A and 1B. With respect to the output, E at node A represents the amplified analog output signal obtained on output line 9 of amplifier 1 In order to obtain DC operating points on line 9 other than zero, a pair of potentiometers 11 and 13 are provided in loop 15. As shown by the dotted connecting lines, the wiper arms of the respective potentiometers 11 and 13 are mechanically linked so that a single mechanical movement moves the wiper arms on the respective resistors 19 and 21 which are of equal...