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Title: Precision absolute value amplifier for a precision voltmeter

Abstract

Bipolar inputs are afforded by the plus inputs of first and second differential input amplifiers. A first gain determining resister is connected between the minus inputs of the differential amplifiers. First and second diodes are connected between the respective minus inputs and the respective outputs of the differential amplifiers. First and second FETs have their gates connected to the outputs of the amplifiers, while their respective source and drain circuits are connected between the respective minus inputs and an output lead extending to a load resister. The output current through the load resister is proportional to the absolute value of the input voltage difference between the bipolar input terminals. A third differential amplifier has its plus input terminal connected to the load resister. A second gain determining resister is connected between the minus input of the third differential amplifier and a voltage source. A third FET has its gate connected to the output of the third amplifier. The source and drain circuit of the third transistor is connected between the minus input of the third amplifier and a voltage-frequency converter, constituting an output device. A polarity detector is also provided, comprising a pair of transistors having their inputs connected tomore » the outputs of the first and second differential amplifiers. The outputs of the polarity detector are connected to gates which switch the output of the voltage-frequency converter between up and down counting outputs.« less

Inventors:
 [1];  [2]
  1. (Berkeley, CA)
  2. (El Sobrante, CA)
Issue Date:
Research Org.:
Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA
OSTI Identifier:
865462
Patent Number(s):
4518877
Assignee:
United States of America as represented by United States (Washington, DC) LBNL
DOE Contract Number:  
AC03-76SF00098
Resource Type:
Patent
Country of Publication:
United States
Language:
English
Subject:
precision; absolute; value; amplifier; voltmeter; bipolar; inputs; afforded; plus; differential; input; amplifiers; determining; resister; connected; minus; diodes; respective; outputs; fets; gates; source; drain; circuits; output; lead; extending; load; current; proportional; voltage; difference; terminals; third; terminal; fet; gate; circuit; transistor; voltage-frequency; converter; constituting; device; polarity; detector; provided; comprising; pair; transistors; switch; counting; output device; input terminal; input terminals; input voltage; output current; differential amplifier; voltage source; absolute value; voltage difference; terminal connected; gates connected; gate connected; frequency converter; differential input; drain circuit; /327/

Citation Formats

Hearn, William E., and Rondeau, Donald J. Precision absolute value amplifier for a precision voltmeter. United States: N. p., 1985. Web.
Hearn, William E., & Rondeau, Donald J. Precision absolute value amplifier for a precision voltmeter. United States.
Hearn, William E., and Rondeau, Donald J. Tue . "Precision absolute value amplifier for a precision voltmeter". United States. https://www.osti.gov/servlets/purl/865462.
@article{osti_865462,
title = {Precision absolute value amplifier for a precision voltmeter},
author = {Hearn, William E. and Rondeau, Donald J.},
abstractNote = {Bipolar inputs are afforded by the plus inputs of first and second differential input amplifiers. A first gain determining resister is connected between the minus inputs of the differential amplifiers. First and second diodes are connected between the respective minus inputs and the respective outputs of the differential amplifiers. First and second FETs have their gates connected to the outputs of the amplifiers, while their respective source and drain circuits are connected between the respective minus inputs and an output lead extending to a load resister. The output current through the load resister is proportional to the absolute value of the input voltage difference between the bipolar input terminals. A third differential amplifier has its plus input terminal connected to the load resister. A second gain determining resister is connected between the minus input of the third differential amplifier and a voltage source. A third FET has its gate connected to the output of the third amplifier. The source and drain circuit of the third transistor is connected between the minus input of the third amplifier and a voltage-frequency converter, constituting an output device. A polarity detector is also provided, comprising a pair of transistors having their inputs connected to the outputs of the first and second differential amplifiers. The outputs of the polarity detector are connected to gates which switch the output of the voltage-frequency converter between up and down counting outputs.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {1985},
month = {1}
}

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