Suitable op-amps/ parameters for subtractor circuits

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Discussion Overview

The discussion revolves around the selection of operational amplifiers (op-amps) for use in analog voltage subtractor circuits. Participants explore various parameters of op-amps that may significantly impact the performance of these circuits, including power supply requirements, accuracy, and dynamic range.

Discussion Character

  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant suggests using general-purpose op-amps like the uA741 for basic applications, while noting the need for a dual supply voltage of +12 and -12 volts.
  • Another participant recommends the LM358 dual op-amp, which operates with a single supply voltage between 5 to 15 volts.
  • Concerns are raised about the importance of slew rate and maximum output voltage, indicating that these factors depend on the desired output voltage and operating frequency.
  • A further contribution emphasizes the significance of input voltage offset and related parameters, explaining how these can limit the analog dynamic range and affect accuracy in subtraction operations.

Areas of Agreement / Disagreement

Participants present multiple viewpoints regarding suitable op-amps and critical parameters, indicating that there is no consensus on a single best approach or solution for all scenarios.

Contextual Notes

Limitations include the dependence on specific application requirements, such as accuracy and output voltage range, which may not be universally applicable across different subtractor circuit designs.

oldfoggy
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Hi all,

I would like to know which op-amps are more suitable for an analog voltage subtractor circuit? Are there any parameters of the op-amp that I should take special note of, which has a more crucial effect on the subtractor circuit?

Thanks for your help in advance!
 
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You can use any general purpose Op Amp such as uA741 as long as you don't need very high level of accuracy.
Take care you need +12 & -12 Volt dual supply for OpAmp.
Or you can use LM358 dual Opamp whis works with single 5 to 15 Volt DC supply.
 
Well there are things like the slew rate and maximum output voltage to take into consideration. It all depends on how much voltage you want at the output as well as what frequency you will be driving it at.
 
You should also review the input voltage offset and other similar offset parameters, because they will limit the analog dynamic range. If individual op-amps have an uncorrected 1-mV input voltage offset, then the quadrature input offset for two op-amps is ±1.4 mV. If you need 10 bit equivalent accuracy, then your subtracted signal amplitude should be at least 1.4 volts. So if the maximum linear output range is ±10 volts, your useful dynamic range is only about 10/1.4 = 7:1.

Bob S
 

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