Operational amplifier as a comparator at high frequencyReasons not to use a 741 op-amp?Can I use LM324 as a Schmitt trigger?Simple op-amp differential amplifierOp amp has a biased outputReduced output of op amp peak detection and hold circuitHow to select the right Operational Amplifier as an impedance converter?Bias voltage of non-inverting op amplifier drops to 0 when input signal connectedHigh negative voltages with op-ampopamp output unstableComparator circuit undesirable fluctuations20kHz sine wave signal amplificationIf there exists a cascade of op amps, does the previous op amp's slew rate affect the later op amp's slew rates?

Can a German sentence have two subjects?

What do you call something that goes against the spirit of the law, but is legal when interpreting the law to the letter?

I probably found a bug with the sudo apt install function

N.B. ligature in Latex

Extreme, but not acceptable situation and I can't start the work tomorrow morning

Do airline pilots ever risk not hearing communication directed to them specifically, from traffic controllers?

Why do we use polarized capacitor?

How old can references or sources in a thesis be?

Why Is Death Allowed In the Matrix?

Why doesn't Newton's third law mean a person bounces back to where they started when they hit the ground?

What does "enim et" mean?

Why is an old chain unsafe?

Is it legal to have the "// (c) 2019 John Smith" header in all files when there are hundreds of contributors?

What makes Graph invariants so useful/important?

What is GPS' 19 year rollover and does it present a cybersecurity issue?

What would happen to a modern skyscraper if it rains micro blackholes?

Why CLRS example on residual networks does not follows its formula?

What defenses are there against being summoned by the Gate spell?

Why did the Germans forbid the possession of pet pigeons in Rostov-on-Don in 1941?

What is the command to reset a PC without deleting any files

How do you conduct xenoanthropology after first contact?

Accidentally leaked the solution to an assignment, what to do now? (I'm the prof)

Copycat chess is back

How is it possible for user's password to be changed after storage was encrypted? (on OS X, Android)



Operational amplifier as a comparator at high frequency


Reasons not to use a 741 op-amp?Can I use LM324 as a Schmitt trigger?Simple op-amp differential amplifierOp amp has a biased outputReduced output of op amp peak detection and hold circuitHow to select the right Operational Amplifier as an impedance converter?Bias voltage of non-inverting op amplifier drops to 0 when input signal connectedHigh negative voltages with op-ampopamp output unstableComparator circuit undesirable fluctuations20kHz sine wave signal amplificationIf there exists a cascade of op amps, does the previous op amp's slew rate affect the later op amp's slew rates?






.everyoneloves__top-leaderboard:empty,.everyoneloves__mid-leaderboard:empty,.everyoneloves__bot-mid-leaderboard:empty margin-bottom:0;








5












$begingroup$


I am trying to generate a sinusoidal PWM signal using analog circuits.
I want to compare my sine wave and triangular wave using an operational amplifier (LM741) which has a rise time of 0.3 µs and slew rate 0.5 V/µs, which will good at 5 kHz theoretically. But I am not getting a good PWM output.



So I first tried to compare the sine wave with a reference voltage (2.2 volt). Sine wave amplitude = 2.5 volt (5 V peak to peak) and frequency 100 Hz and 5 kHz.



Enter image description here



  • At low frequency (say 100 Hz), the output is good

  • At high frequency (say 5 kHz), the output is too bad.

Enter image description here



Enter image description here



What will be the problem...



If the response is the problem of the comparator, but the slew rate is 0.5 V/µs.



Calculation of slew rate for a sinusoidal signal...



Slew rate= Vm * 2pi * Frequency



 = 5 V * 2pi* 5000 Hz

= 1570796 volt per second or 0.15 V/µs


Theoretically the slew rate of 0.5 V/µs will be OK for a sinusoidal signal of 5 kHz and 5 volt peak to peak. But in my case the signal is distorted.



Where am I wrong?










share|improve this question











$endgroup$











  • $begingroup$
    It looks like there's a significant lag/delay in the output's response w.r.t. the input signal (~30µs?). What may be causing this? What's connected to the output? 'Scope probe only?
    $endgroup$
    – JimmyB
    2 days ago






  • 5




    $begingroup$
    Why you shouldn't use the 741.
    $endgroup$
    – JRE
    2 days ago










  • $begingroup$
    For 5Khz i thought 741 will be ok, for what i calculated .Orelse sure i will change the opp amp which having high slew rate and i will update it.......@JRE
    $endgroup$
    – Nihal
    2 days ago







  • 1




    $begingroup$
    You're latching up.
    $endgroup$
    – Scott Seidman
    2 days ago






  • 1




    $begingroup$
    Note that this question is about the theory behind the calculations. Telling OP to change his OP-amp does nothing to answer the question. It just solves the problem without OP knowing why.
    $endgroup$
    – pipe
    2 days ago

















5












$begingroup$


I am trying to generate a sinusoidal PWM signal using analog circuits.
I want to compare my sine wave and triangular wave using an operational amplifier (LM741) which has a rise time of 0.3 µs and slew rate 0.5 V/µs, which will good at 5 kHz theoretically. But I am not getting a good PWM output.



So I first tried to compare the sine wave with a reference voltage (2.2 volt). Sine wave amplitude = 2.5 volt (5 V peak to peak) and frequency 100 Hz and 5 kHz.



Enter image description here



  • At low frequency (say 100 Hz), the output is good

  • At high frequency (say 5 kHz), the output is too bad.

Enter image description here



Enter image description here



What will be the problem...



If the response is the problem of the comparator, but the slew rate is 0.5 V/µs.



Calculation of slew rate for a sinusoidal signal...



Slew rate= Vm * 2pi * Frequency



 = 5 V * 2pi* 5000 Hz

= 1570796 volt per second or 0.15 V/µs


Theoretically the slew rate of 0.5 V/µs will be OK for a sinusoidal signal of 5 kHz and 5 volt peak to peak. But in my case the signal is distorted.



Where am I wrong?










share|improve this question











$endgroup$











  • $begingroup$
    It looks like there's a significant lag/delay in the output's response w.r.t. the input signal (~30µs?). What may be causing this? What's connected to the output? 'Scope probe only?
    $endgroup$
    – JimmyB
    2 days ago






  • 5




    $begingroup$
    Why you shouldn't use the 741.
    $endgroup$
    – JRE
    2 days ago










  • $begingroup$
    For 5Khz i thought 741 will be ok, for what i calculated .Orelse sure i will change the opp amp which having high slew rate and i will update it.......@JRE
    $endgroup$
    – Nihal
    2 days ago







  • 1




    $begingroup$
    You're latching up.
    $endgroup$
    – Scott Seidman
    2 days ago






  • 1




    $begingroup$
    Note that this question is about the theory behind the calculations. Telling OP to change his OP-amp does nothing to answer the question. It just solves the problem without OP knowing why.
    $endgroup$
    – pipe
    2 days ago













5












5








5





$begingroup$


I am trying to generate a sinusoidal PWM signal using analog circuits.
I want to compare my sine wave and triangular wave using an operational amplifier (LM741) which has a rise time of 0.3 µs and slew rate 0.5 V/µs, which will good at 5 kHz theoretically. But I am not getting a good PWM output.



So I first tried to compare the sine wave with a reference voltage (2.2 volt). Sine wave amplitude = 2.5 volt (5 V peak to peak) and frequency 100 Hz and 5 kHz.



Enter image description here



  • At low frequency (say 100 Hz), the output is good

  • At high frequency (say 5 kHz), the output is too bad.

Enter image description here



Enter image description here



What will be the problem...



If the response is the problem of the comparator, but the slew rate is 0.5 V/µs.



Calculation of slew rate for a sinusoidal signal...



Slew rate= Vm * 2pi * Frequency



 = 5 V * 2pi* 5000 Hz

= 1570796 volt per second or 0.15 V/µs


Theoretically the slew rate of 0.5 V/µs will be OK for a sinusoidal signal of 5 kHz and 5 volt peak to peak. But in my case the signal is distorted.



Where am I wrong?










share|improve this question











$endgroup$




I am trying to generate a sinusoidal PWM signal using analog circuits.
I want to compare my sine wave and triangular wave using an operational amplifier (LM741) which has a rise time of 0.3 µs and slew rate 0.5 V/µs, which will good at 5 kHz theoretically. But I am not getting a good PWM output.



So I first tried to compare the sine wave with a reference voltage (2.2 volt). Sine wave amplitude = 2.5 volt (5 V peak to peak) and frequency 100 Hz and 5 kHz.



Enter image description here



  • At low frequency (say 100 Hz), the output is good

  • At high frequency (say 5 kHz), the output is too bad.

Enter image description here



Enter image description here



What will be the problem...



If the response is the problem of the comparator, but the slew rate is 0.5 V/µs.



Calculation of slew rate for a sinusoidal signal...



Slew rate= Vm * 2pi * Frequency



 = 5 V * 2pi* 5000 Hz

= 1570796 volt per second or 0.15 V/µs


Theoretically the slew rate of 0.5 V/µs will be OK for a sinusoidal signal of 5 kHz and 5 volt peak to peak. But in my case the signal is distorted.



Where am I wrong?







operational-amplifier comparator






share|improve this question















share|improve this question













share|improve this question




share|improve this question








edited 2 days ago









Peter Mortensen

1,60031422




1,60031422










asked 2 days ago









NihalNihal

518




518











  • $begingroup$
    It looks like there's a significant lag/delay in the output's response w.r.t. the input signal (~30µs?). What may be causing this? What's connected to the output? 'Scope probe only?
    $endgroup$
    – JimmyB
    2 days ago






  • 5




    $begingroup$
    Why you shouldn't use the 741.
    $endgroup$
    – JRE
    2 days ago










  • $begingroup$
    For 5Khz i thought 741 will be ok, for what i calculated .Orelse sure i will change the opp amp which having high slew rate and i will update it.......@JRE
    $endgroup$
    – Nihal
    2 days ago







  • 1




    $begingroup$
    You're latching up.
    $endgroup$
    – Scott Seidman
    2 days ago






  • 1




    $begingroup$
    Note that this question is about the theory behind the calculations. Telling OP to change his OP-amp does nothing to answer the question. It just solves the problem without OP knowing why.
    $endgroup$
    – pipe
    2 days ago
















  • $begingroup$
    It looks like there's a significant lag/delay in the output's response w.r.t. the input signal (~30µs?). What may be causing this? What's connected to the output? 'Scope probe only?
    $endgroup$
    – JimmyB
    2 days ago






  • 5




    $begingroup$
    Why you shouldn't use the 741.
    $endgroup$
    – JRE
    2 days ago










  • $begingroup$
    For 5Khz i thought 741 will be ok, for what i calculated .Orelse sure i will change the opp amp which having high slew rate and i will update it.......@JRE
    $endgroup$
    – Nihal
    2 days ago







  • 1




    $begingroup$
    You're latching up.
    $endgroup$
    – Scott Seidman
    2 days ago






  • 1




    $begingroup$
    Note that this question is about the theory behind the calculations. Telling OP to change his OP-amp does nothing to answer the question. It just solves the problem without OP knowing why.
    $endgroup$
    – pipe
    2 days ago















$begingroup$
It looks like there's a significant lag/delay in the output's response w.r.t. the input signal (~30µs?). What may be causing this? What's connected to the output? 'Scope probe only?
$endgroup$
– JimmyB
2 days ago




$begingroup$
It looks like there's a significant lag/delay in the output's response w.r.t. the input signal (~30µs?). What may be causing this? What's connected to the output? 'Scope probe only?
$endgroup$
– JimmyB
2 days ago




5




5




$begingroup$
Why you shouldn't use the 741.
$endgroup$
– JRE
2 days ago




$begingroup$
Why you shouldn't use the 741.
$endgroup$
– JRE
2 days ago












$begingroup$
For 5Khz i thought 741 will be ok, for what i calculated .Orelse sure i will change the opp amp which having high slew rate and i will update it.......@JRE
$endgroup$
– Nihal
2 days ago





$begingroup$
For 5Khz i thought 741 will be ok, for what i calculated .Orelse sure i will change the opp amp which having high slew rate and i will update it.......@JRE
$endgroup$
– Nihal
2 days ago





1




1




$begingroup$
You're latching up.
$endgroup$
– Scott Seidman
2 days ago




$begingroup$
You're latching up.
$endgroup$
– Scott Seidman
2 days ago




1




1




$begingroup$
Note that this question is about the theory behind the calculations. Telling OP to change his OP-amp does nothing to answer the question. It just solves the problem without OP knowing why.
$endgroup$
– pipe
2 days ago




$begingroup$
Note that this question is about the theory behind the calculations. Telling OP to change his OP-amp does nothing to answer the question. It just solves the problem without OP knowing why.
$endgroup$
– pipe
2 days ago










5 Answers
5






active

oldest

votes


















8












$begingroup$

The recommendations for you are very simple.



  1. Use a comparator for this application instead of an opamp.


  2. Select a newer part that operates with orders of magnitude faster response time.


It would be the very best thing if the 741 could be eradicated from face of the earth.



Here is what can be achieved with the venerable LM393 at 5kHz. The shown circuit will work even up to about 50kHz before the delay of the LM393 starts to distort the PWM duty cycle.



enter image description here



enter image description here






share|improve this answer











$endgroup$












  • $begingroup$
    Sure friend i will change the opp amp or by using comparator, i will update the data soon.
    $endgroup$
    – Nihal
    2 days ago






  • 1




    $begingroup$
    @Nihal - If you show some new results in the question do not delete your original material, Instead add it as an update at the end. The reason for this is that hopefully this question can be a reference to future readers that are looking for information as being discussed here. If you delete the original material the answers here would no longer make much sense to a future reader.
    $endgroup$
    – Michael Karas
    2 days ago






  • 1




    $begingroup$
    "It would be the very best thing if the 741 could be eradicated from face of the earth." ok - I'll bite. what's your reasons?
    $endgroup$
    – UKMonkey
    2 days ago






  • 2




    $begingroup$
    @UKMonkey the 741 was first released in 1968. And while it was a fantastic IC at the time, there are vastly superior op-amps available with lower input offset voltage, higher bandwidth, higher input impedance, etc. Most people lean the "ideal op-amp" first, and then immediately jump to one of the most non-ideal op-amps in practice, and wonder why their design doesn't work.
    $endgroup$
    – CurtisHx
    2 days ago










  • $begingroup$
    LM741 might still be in the textbooks...
    $endgroup$
    – Peter Mortensen
    2 days ago


















3












$begingroup$

Opamps work slowly with low power supply voltages. In addition they are designed to work in linear region. As saturated, like in your application, the response has an unpredictable dead time. before the internal saturation is vanished.



I can only repeat what's already said: Get a comparator. 741 was a remarkable step forward half a century ago, but things have developed better since those days.






share|improve this answer









$endgroup$












  • $begingroup$
    Thank you for your response friend, i will update it after changing the opp amp.
    $endgroup$
    – Nihal
    2 days ago






  • 2




    $begingroup$
    @Nihal Comparators have other precautions. They are high speed circuits like logic parts. You must have acceptably short wires and coupling capacitors between supply voltage inputs. Making the circuit with 0,5 meter long wires onto a breadboard without coupling caps (I have seen those attempts) will be useless.
    $endgroup$
    – user287001
    2 days ago










  • $begingroup$
    Ok friend I will even buy a comparator and I will check with it.
    $endgroup$
    – Nihal
    2 days ago


















1












$begingroup$

Op-amps are susceptible to latch-up. Recovering from saturation at the rails is not an automatic thing. The ratings you are reading a for the op amp working in a feedback mode, not an open loop mode. You would need to find an op amp designed to minimize latch-up, or better yet, when you need a comparator, buy a comparator.






share|improve this answer









$endgroup$








  • 1




    $begingroup$
    Yes, and/or phase inversion, depending on the op-amp type.
    $endgroup$
    – Peter Mortensen
    2 days ago



















1












$begingroup$

You may try this, if you want a discrete solution





schematic





simulate this circuit – Schematic created using CircuitLab



The speed will be limited by Rin (10Kohm) and Miller Effect Cin (100pF?), thus propagation delay will be about 1 uS.






share|improve this answer











$endgroup$












  • $begingroup$
    What is it? A Schmitt trigger?
    $endgroup$
    – Peter Mortensen
    2 days ago










  • $begingroup$
    The differential pair is biased at VDD/2. R8 does provide 1% positive feedback, to reduce the risk of oscillation during the linear region. Notice I included over-voltage protection.
    $endgroup$
    – analogsystemsrf
    2 days ago


















0












$begingroup$

Most garden variety op-amps have internal compensation in the form of a chip capacitor.



This makes them very slow, but more stable in analog circuits.



Why not use a cheap comparator like LM393?






share|improve this answer











$endgroup$













    Your Answer





    StackExchange.ifUsing("editor", function ()
    return StackExchange.using("mathjaxEditing", function ()
    StackExchange.MarkdownEditor.creationCallbacks.add(function (editor, postfix)
    StackExchange.mathjaxEditing.prepareWmdForMathJax(editor, postfix, [["\$", "\$"]]);
    );
    );
    , "mathjax-editing");

    StackExchange.ifUsing("editor", function ()
    return StackExchange.using("schematics", function ()
    StackExchange.schematics.init();
    );
    , "cicuitlab");

    StackExchange.ready(function()
    var channelOptions =
    tags: "".split(" "),
    id: "135"
    ;
    initTagRenderer("".split(" "), "".split(" "), channelOptions);

    StackExchange.using("externalEditor", function()
    // Have to fire editor after snippets, if snippets enabled
    if (StackExchange.settings.snippets.snippetsEnabled)
    StackExchange.using("snippets", function()
    createEditor();
    );

    else
    createEditor();

    );

    function createEditor()
    StackExchange.prepareEditor(
    heartbeatType: 'answer',
    autoActivateHeartbeat: false,
    convertImagesToLinks: false,
    noModals: true,
    showLowRepImageUploadWarning: true,
    reputationToPostImages: null,
    bindNavPrevention: true,
    postfix: "",
    imageUploader:
    brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
    contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/3.0/"u003ecc by-sa 3.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
    allowUrls: true
    ,
    onDemand: true,
    discardSelector: ".discard-answer"
    ,immediatelyShowMarkdownHelp:true
    );



    );













    draft saved

    draft discarded


















    StackExchange.ready(
    function ()
    StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2felectronics.stackexchange.com%2fquestions%2f430885%2foperational-amplifier-as-a-comparator-at-high-frequency%23new-answer', 'question_page');

    );

    Post as a guest















    Required, but never shown

























    5 Answers
    5






    active

    oldest

    votes








    5 Answers
    5






    active

    oldest

    votes









    active

    oldest

    votes






    active

    oldest

    votes









    8












    $begingroup$

    The recommendations for you are very simple.



    1. Use a comparator for this application instead of an opamp.


    2. Select a newer part that operates with orders of magnitude faster response time.


    It would be the very best thing if the 741 could be eradicated from face of the earth.



    Here is what can be achieved with the venerable LM393 at 5kHz. The shown circuit will work even up to about 50kHz before the delay of the LM393 starts to distort the PWM duty cycle.



    enter image description here



    enter image description here






    share|improve this answer











    $endgroup$












    • $begingroup$
      Sure friend i will change the opp amp or by using comparator, i will update the data soon.
      $endgroup$
      – Nihal
      2 days ago






    • 1




      $begingroup$
      @Nihal - If you show some new results in the question do not delete your original material, Instead add it as an update at the end. The reason for this is that hopefully this question can be a reference to future readers that are looking for information as being discussed here. If you delete the original material the answers here would no longer make much sense to a future reader.
      $endgroup$
      – Michael Karas
      2 days ago






    • 1




      $begingroup$
      "It would be the very best thing if the 741 could be eradicated from face of the earth." ok - I'll bite. what's your reasons?
      $endgroup$
      – UKMonkey
      2 days ago






    • 2




      $begingroup$
      @UKMonkey the 741 was first released in 1968. And while it was a fantastic IC at the time, there are vastly superior op-amps available with lower input offset voltage, higher bandwidth, higher input impedance, etc. Most people lean the "ideal op-amp" first, and then immediately jump to one of the most non-ideal op-amps in practice, and wonder why their design doesn't work.
      $endgroup$
      – CurtisHx
      2 days ago










    • $begingroup$
      LM741 might still be in the textbooks...
      $endgroup$
      – Peter Mortensen
      2 days ago















    8












    $begingroup$

    The recommendations for you are very simple.



    1. Use a comparator for this application instead of an opamp.


    2. Select a newer part that operates with orders of magnitude faster response time.


    It would be the very best thing if the 741 could be eradicated from face of the earth.



    Here is what can be achieved with the venerable LM393 at 5kHz. The shown circuit will work even up to about 50kHz before the delay of the LM393 starts to distort the PWM duty cycle.



    enter image description here



    enter image description here






    share|improve this answer











    $endgroup$












    • $begingroup$
      Sure friend i will change the opp amp or by using comparator, i will update the data soon.
      $endgroup$
      – Nihal
      2 days ago






    • 1




      $begingroup$
      @Nihal - If you show some new results in the question do not delete your original material, Instead add it as an update at the end. The reason for this is that hopefully this question can be a reference to future readers that are looking for information as being discussed here. If you delete the original material the answers here would no longer make much sense to a future reader.
      $endgroup$
      – Michael Karas
      2 days ago






    • 1




      $begingroup$
      "It would be the very best thing if the 741 could be eradicated from face of the earth." ok - I'll bite. what's your reasons?
      $endgroup$
      – UKMonkey
      2 days ago






    • 2




      $begingroup$
      @UKMonkey the 741 was first released in 1968. And while it was a fantastic IC at the time, there are vastly superior op-amps available with lower input offset voltage, higher bandwidth, higher input impedance, etc. Most people lean the "ideal op-amp" first, and then immediately jump to one of the most non-ideal op-amps in practice, and wonder why their design doesn't work.
      $endgroup$
      – CurtisHx
      2 days ago










    • $begingroup$
      LM741 might still be in the textbooks...
      $endgroup$
      – Peter Mortensen
      2 days ago













    8












    8








    8





    $begingroup$

    The recommendations for you are very simple.



    1. Use a comparator for this application instead of an opamp.


    2. Select a newer part that operates with orders of magnitude faster response time.


    It would be the very best thing if the 741 could be eradicated from face of the earth.



    Here is what can be achieved with the venerable LM393 at 5kHz. The shown circuit will work even up to about 50kHz before the delay of the LM393 starts to distort the PWM duty cycle.



    enter image description here



    enter image description here






    share|improve this answer











    $endgroup$



    The recommendations for you are very simple.



    1. Use a comparator for this application instead of an opamp.


    2. Select a newer part that operates with orders of magnitude faster response time.


    It would be the very best thing if the 741 could be eradicated from face of the earth.



    Here is what can be achieved with the venerable LM393 at 5kHz. The shown circuit will work even up to about 50kHz before the delay of the LM393 starts to distort the PWM duty cycle.



    enter image description here



    enter image description here







    share|improve this answer














    share|improve this answer



    share|improve this answer








    edited 2 days ago

























    answered 2 days ago









    Michael KarasMichael Karas

    45.2k348105




    45.2k348105











    • $begingroup$
      Sure friend i will change the opp amp or by using comparator, i will update the data soon.
      $endgroup$
      – Nihal
      2 days ago






    • 1




      $begingroup$
      @Nihal - If you show some new results in the question do not delete your original material, Instead add it as an update at the end. The reason for this is that hopefully this question can be a reference to future readers that are looking for information as being discussed here. If you delete the original material the answers here would no longer make much sense to a future reader.
      $endgroup$
      – Michael Karas
      2 days ago






    • 1




      $begingroup$
      "It would be the very best thing if the 741 could be eradicated from face of the earth." ok - I'll bite. what's your reasons?
      $endgroup$
      – UKMonkey
      2 days ago






    • 2




      $begingroup$
      @UKMonkey the 741 was first released in 1968. And while it was a fantastic IC at the time, there are vastly superior op-amps available with lower input offset voltage, higher bandwidth, higher input impedance, etc. Most people lean the "ideal op-amp" first, and then immediately jump to one of the most non-ideal op-amps in practice, and wonder why their design doesn't work.
      $endgroup$
      – CurtisHx
      2 days ago










    • $begingroup$
      LM741 might still be in the textbooks...
      $endgroup$
      – Peter Mortensen
      2 days ago
















    • $begingroup$
      Sure friend i will change the opp amp or by using comparator, i will update the data soon.
      $endgroup$
      – Nihal
      2 days ago






    • 1




      $begingroup$
      @Nihal - If you show some new results in the question do not delete your original material, Instead add it as an update at the end. The reason for this is that hopefully this question can be a reference to future readers that are looking for information as being discussed here. If you delete the original material the answers here would no longer make much sense to a future reader.
      $endgroup$
      – Michael Karas
      2 days ago






    • 1




      $begingroup$
      "It would be the very best thing if the 741 could be eradicated from face of the earth." ok - I'll bite. what's your reasons?
      $endgroup$
      – UKMonkey
      2 days ago






    • 2




      $begingroup$
      @UKMonkey the 741 was first released in 1968. And while it was a fantastic IC at the time, there are vastly superior op-amps available with lower input offset voltage, higher bandwidth, higher input impedance, etc. Most people lean the "ideal op-amp" first, and then immediately jump to one of the most non-ideal op-amps in practice, and wonder why their design doesn't work.
      $endgroup$
      – CurtisHx
      2 days ago










    • $begingroup$
      LM741 might still be in the textbooks...
      $endgroup$
      – Peter Mortensen
      2 days ago















    $begingroup$
    Sure friend i will change the opp amp or by using comparator, i will update the data soon.
    $endgroup$
    – Nihal
    2 days ago




    $begingroup$
    Sure friend i will change the opp amp or by using comparator, i will update the data soon.
    $endgroup$
    – Nihal
    2 days ago




    1




    1




    $begingroup$
    @Nihal - If you show some new results in the question do not delete your original material, Instead add it as an update at the end. The reason for this is that hopefully this question can be a reference to future readers that are looking for information as being discussed here. If you delete the original material the answers here would no longer make much sense to a future reader.
    $endgroup$
    – Michael Karas
    2 days ago




    $begingroup$
    @Nihal - If you show some new results in the question do not delete your original material, Instead add it as an update at the end. The reason for this is that hopefully this question can be a reference to future readers that are looking for information as being discussed here. If you delete the original material the answers here would no longer make much sense to a future reader.
    $endgroup$
    – Michael Karas
    2 days ago




    1




    1




    $begingroup$
    "It would be the very best thing if the 741 could be eradicated from face of the earth." ok - I'll bite. what's your reasons?
    $endgroup$
    – UKMonkey
    2 days ago




    $begingroup$
    "It would be the very best thing if the 741 could be eradicated from face of the earth." ok - I'll bite. what's your reasons?
    $endgroup$
    – UKMonkey
    2 days ago




    2




    2




    $begingroup$
    @UKMonkey the 741 was first released in 1968. And while it was a fantastic IC at the time, there are vastly superior op-amps available with lower input offset voltage, higher bandwidth, higher input impedance, etc. Most people lean the "ideal op-amp" first, and then immediately jump to one of the most non-ideal op-amps in practice, and wonder why their design doesn't work.
    $endgroup$
    – CurtisHx
    2 days ago




    $begingroup$
    @UKMonkey the 741 was first released in 1968. And while it was a fantastic IC at the time, there are vastly superior op-amps available with lower input offset voltage, higher bandwidth, higher input impedance, etc. Most people lean the "ideal op-amp" first, and then immediately jump to one of the most non-ideal op-amps in practice, and wonder why their design doesn't work.
    $endgroup$
    – CurtisHx
    2 days ago












    $begingroup$
    LM741 might still be in the textbooks...
    $endgroup$
    – Peter Mortensen
    2 days ago




    $begingroup$
    LM741 might still be in the textbooks...
    $endgroup$
    – Peter Mortensen
    2 days ago













    3












    $begingroup$

    Opamps work slowly with low power supply voltages. In addition they are designed to work in linear region. As saturated, like in your application, the response has an unpredictable dead time. before the internal saturation is vanished.



    I can only repeat what's already said: Get a comparator. 741 was a remarkable step forward half a century ago, but things have developed better since those days.






    share|improve this answer









    $endgroup$












    • $begingroup$
      Thank you for your response friend, i will update it after changing the opp amp.
      $endgroup$
      – Nihal
      2 days ago






    • 2




      $begingroup$
      @Nihal Comparators have other precautions. They are high speed circuits like logic parts. You must have acceptably short wires and coupling capacitors between supply voltage inputs. Making the circuit with 0,5 meter long wires onto a breadboard without coupling caps (I have seen those attempts) will be useless.
      $endgroup$
      – user287001
      2 days ago










    • $begingroup$
      Ok friend I will even buy a comparator and I will check with it.
      $endgroup$
      – Nihal
      2 days ago















    3












    $begingroup$

    Opamps work slowly with low power supply voltages. In addition they are designed to work in linear region. As saturated, like in your application, the response has an unpredictable dead time. before the internal saturation is vanished.



    I can only repeat what's already said: Get a comparator. 741 was a remarkable step forward half a century ago, but things have developed better since those days.






    share|improve this answer









    $endgroup$












    • $begingroup$
      Thank you for your response friend, i will update it after changing the opp amp.
      $endgroup$
      – Nihal
      2 days ago






    • 2




      $begingroup$
      @Nihal Comparators have other precautions. They are high speed circuits like logic parts. You must have acceptably short wires and coupling capacitors between supply voltage inputs. Making the circuit with 0,5 meter long wires onto a breadboard without coupling caps (I have seen those attempts) will be useless.
      $endgroup$
      – user287001
      2 days ago










    • $begingroup$
      Ok friend I will even buy a comparator and I will check with it.
      $endgroup$
      – Nihal
      2 days ago













    3












    3








    3





    $begingroup$

    Opamps work slowly with low power supply voltages. In addition they are designed to work in linear region. As saturated, like in your application, the response has an unpredictable dead time. before the internal saturation is vanished.



    I can only repeat what's already said: Get a comparator. 741 was a remarkable step forward half a century ago, but things have developed better since those days.






    share|improve this answer









    $endgroup$



    Opamps work slowly with low power supply voltages. In addition they are designed to work in linear region. As saturated, like in your application, the response has an unpredictable dead time. before the internal saturation is vanished.



    I can only repeat what's already said: Get a comparator. 741 was a remarkable step forward half a century ago, but things have developed better since those days.







    share|improve this answer












    share|improve this answer



    share|improve this answer










    answered 2 days ago









    user287001user287001

    9,6791517




    9,6791517











    • $begingroup$
      Thank you for your response friend, i will update it after changing the opp amp.
      $endgroup$
      – Nihal
      2 days ago






    • 2




      $begingroup$
      @Nihal Comparators have other precautions. They are high speed circuits like logic parts. You must have acceptably short wires and coupling capacitors between supply voltage inputs. Making the circuit with 0,5 meter long wires onto a breadboard without coupling caps (I have seen those attempts) will be useless.
      $endgroup$
      – user287001
      2 days ago










    • $begingroup$
      Ok friend I will even buy a comparator and I will check with it.
      $endgroup$
      – Nihal
      2 days ago
















    • $begingroup$
      Thank you for your response friend, i will update it after changing the opp amp.
      $endgroup$
      – Nihal
      2 days ago






    • 2




      $begingroup$
      @Nihal Comparators have other precautions. They are high speed circuits like logic parts. You must have acceptably short wires and coupling capacitors between supply voltage inputs. Making the circuit with 0,5 meter long wires onto a breadboard without coupling caps (I have seen those attempts) will be useless.
      $endgroup$
      – user287001
      2 days ago










    • $begingroup$
      Ok friend I will even buy a comparator and I will check with it.
      $endgroup$
      – Nihal
      2 days ago















    $begingroup$
    Thank you for your response friend, i will update it after changing the opp amp.
    $endgroup$
    – Nihal
    2 days ago




    $begingroup$
    Thank you for your response friend, i will update it after changing the opp amp.
    $endgroup$
    – Nihal
    2 days ago




    2




    2




    $begingroup$
    @Nihal Comparators have other precautions. They are high speed circuits like logic parts. You must have acceptably short wires and coupling capacitors between supply voltage inputs. Making the circuit with 0,5 meter long wires onto a breadboard without coupling caps (I have seen those attempts) will be useless.
    $endgroup$
    – user287001
    2 days ago




    $begingroup$
    @Nihal Comparators have other precautions. They are high speed circuits like logic parts. You must have acceptably short wires and coupling capacitors between supply voltage inputs. Making the circuit with 0,5 meter long wires onto a breadboard without coupling caps (I have seen those attempts) will be useless.
    $endgroup$
    – user287001
    2 days ago












    $begingroup$
    Ok friend I will even buy a comparator and I will check with it.
    $endgroup$
    – Nihal
    2 days ago




    $begingroup$
    Ok friend I will even buy a comparator and I will check with it.
    $endgroup$
    – Nihal
    2 days ago











    1












    $begingroup$

    Op-amps are susceptible to latch-up. Recovering from saturation at the rails is not an automatic thing. The ratings you are reading a for the op amp working in a feedback mode, not an open loop mode. You would need to find an op amp designed to minimize latch-up, or better yet, when you need a comparator, buy a comparator.






    share|improve this answer









    $endgroup$








    • 1




      $begingroup$
      Yes, and/or phase inversion, depending on the op-amp type.
      $endgroup$
      – Peter Mortensen
      2 days ago
















    1












    $begingroup$

    Op-amps are susceptible to latch-up. Recovering from saturation at the rails is not an automatic thing. The ratings you are reading a for the op amp working in a feedback mode, not an open loop mode. You would need to find an op amp designed to minimize latch-up, or better yet, when you need a comparator, buy a comparator.






    share|improve this answer









    $endgroup$








    • 1




      $begingroup$
      Yes, and/or phase inversion, depending on the op-amp type.
      $endgroup$
      – Peter Mortensen
      2 days ago














    1












    1








    1





    $begingroup$

    Op-amps are susceptible to latch-up. Recovering from saturation at the rails is not an automatic thing. The ratings you are reading a for the op amp working in a feedback mode, not an open loop mode. You would need to find an op amp designed to minimize latch-up, or better yet, when you need a comparator, buy a comparator.






    share|improve this answer









    $endgroup$



    Op-amps are susceptible to latch-up. Recovering from saturation at the rails is not an automatic thing. The ratings you are reading a for the op amp working in a feedback mode, not an open loop mode. You would need to find an op amp designed to minimize latch-up, or better yet, when you need a comparator, buy a comparator.







    share|improve this answer












    share|improve this answer



    share|improve this answer










    answered 2 days ago









    Scott SeidmanScott Seidman

    22.7k43286




    22.7k43286







    • 1




      $begingroup$
      Yes, and/or phase inversion, depending on the op-amp type.
      $endgroup$
      – Peter Mortensen
      2 days ago













    • 1




      $begingroup$
      Yes, and/or phase inversion, depending on the op-amp type.
      $endgroup$
      – Peter Mortensen
      2 days ago








    1




    1




    $begingroup$
    Yes, and/or phase inversion, depending on the op-amp type.
    $endgroup$
    – Peter Mortensen
    2 days ago





    $begingroup$
    Yes, and/or phase inversion, depending on the op-amp type.
    $endgroup$
    – Peter Mortensen
    2 days ago












    1












    $begingroup$

    You may try this, if you want a discrete solution





    schematic





    simulate this circuit – Schematic created using CircuitLab



    The speed will be limited by Rin (10Kohm) and Miller Effect Cin (100pF?), thus propagation delay will be about 1 uS.






    share|improve this answer











    $endgroup$












    • $begingroup$
      What is it? A Schmitt trigger?
      $endgroup$
      – Peter Mortensen
      2 days ago










    • $begingroup$
      The differential pair is biased at VDD/2. R8 does provide 1% positive feedback, to reduce the risk of oscillation during the linear region. Notice I included over-voltage protection.
      $endgroup$
      – analogsystemsrf
      2 days ago















    1












    $begingroup$

    You may try this, if you want a discrete solution





    schematic





    simulate this circuit – Schematic created using CircuitLab



    The speed will be limited by Rin (10Kohm) and Miller Effect Cin (100pF?), thus propagation delay will be about 1 uS.






    share|improve this answer











    $endgroup$












    • $begingroup$
      What is it? A Schmitt trigger?
      $endgroup$
      – Peter Mortensen
      2 days ago










    • $begingroup$
      The differential pair is biased at VDD/2. R8 does provide 1% positive feedback, to reduce the risk of oscillation during the linear region. Notice I included over-voltage protection.
      $endgroup$
      – analogsystemsrf
      2 days ago













    1












    1








    1





    $begingroup$

    You may try this, if you want a discrete solution





    schematic





    simulate this circuit – Schematic created using CircuitLab



    The speed will be limited by Rin (10Kohm) and Miller Effect Cin (100pF?), thus propagation delay will be about 1 uS.






    share|improve this answer











    $endgroup$



    You may try this, if you want a discrete solution





    schematic





    simulate this circuit – Schematic created using CircuitLab



    The speed will be limited by Rin (10Kohm) and Miller Effect Cin (100pF?), thus propagation delay will be about 1 uS.







    share|improve this answer














    share|improve this answer



    share|improve this answer








    edited 50 mins ago

























    answered 2 days ago









    analogsystemsrfanalogsystemsrf

    16k2822




    16k2822











    • $begingroup$
      What is it? A Schmitt trigger?
      $endgroup$
      – Peter Mortensen
      2 days ago










    • $begingroup$
      The differential pair is biased at VDD/2. R8 does provide 1% positive feedback, to reduce the risk of oscillation during the linear region. Notice I included over-voltage protection.
      $endgroup$
      – analogsystemsrf
      2 days ago
















    • $begingroup$
      What is it? A Schmitt trigger?
      $endgroup$
      – Peter Mortensen
      2 days ago










    • $begingroup$
      The differential pair is biased at VDD/2. R8 does provide 1% positive feedback, to reduce the risk of oscillation during the linear region. Notice I included over-voltage protection.
      $endgroup$
      – analogsystemsrf
      2 days ago















    $begingroup$
    What is it? A Schmitt trigger?
    $endgroup$
    – Peter Mortensen
    2 days ago




    $begingroup$
    What is it? A Schmitt trigger?
    $endgroup$
    – Peter Mortensen
    2 days ago












    $begingroup$
    The differential pair is biased at VDD/2. R8 does provide 1% positive feedback, to reduce the risk of oscillation during the linear region. Notice I included over-voltage protection.
    $endgroup$
    – analogsystemsrf
    2 days ago




    $begingroup$
    The differential pair is biased at VDD/2. R8 does provide 1% positive feedback, to reduce the risk of oscillation during the linear region. Notice I included over-voltage protection.
    $endgroup$
    – analogsystemsrf
    2 days ago











    0












    $begingroup$

    Most garden variety op-amps have internal compensation in the form of a chip capacitor.



    This makes them very slow, but more stable in analog circuits.



    Why not use a cheap comparator like LM393?






    share|improve this answer











    $endgroup$

















      0












      $begingroup$

      Most garden variety op-amps have internal compensation in the form of a chip capacitor.



      This makes them very slow, but more stable in analog circuits.



      Why not use a cheap comparator like LM393?






      share|improve this answer











      $endgroup$















        0












        0








        0





        $begingroup$

        Most garden variety op-amps have internal compensation in the form of a chip capacitor.



        This makes them very slow, but more stable in analog circuits.



        Why not use a cheap comparator like LM393?






        share|improve this answer











        $endgroup$



        Most garden variety op-amps have internal compensation in the form of a chip capacitor.



        This makes them very slow, but more stable in analog circuits.



        Why not use a cheap comparator like LM393?







        share|improve this answer














        share|improve this answer



        share|improve this answer








        edited 2 days ago









        Renan

        4,32222244




        4,32222244










        answered 2 days ago









        AutisticAutistic

        7,50921633




        7,50921633



























            draft saved

            draft discarded
















































            Thanks for contributing an answer to Electrical Engineering Stack Exchange!


            • Please be sure to answer the question. Provide details and share your research!

            But avoid


            • Asking for help, clarification, or responding to other answers.

            • Making statements based on opinion; back them up with references or personal experience.

            Use MathJax to format equations. MathJax reference.


            To learn more, see our tips on writing great answers.




            draft saved


            draft discarded














            StackExchange.ready(
            function ()
            StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2felectronics.stackexchange.com%2fquestions%2f430885%2foperational-amplifier-as-a-comparator-at-high-frequency%23new-answer', 'question_page');

            );

            Post as a guest















            Required, but never shown





















































            Required, but never shown














            Required, but never shown












            Required, but never shown







            Required, but never shown

































            Required, but never shown














            Required, but never shown












            Required, but never shown







            Required, but never shown







            Popular posts from this blog

            Tamil (spriik) Luke uk diar | Nawigatjuun

            Align equal signs while including text over equalitiesAMS align: left aligned text/math plus multicolumn alignmentMultiple alignmentsAligning equations in multiple placesNumbering and aligning an equation with multiple columnsHow to align one equation with another multline equationUsing \ in environments inside the begintabularxNumber equations and preserving alignment of equal signsHow can I align equations to the left and to the right?Double equation alignment problem within align enviromentAligned within align: Why are they right-aligned?

            Training a classifier when some of the features are unknownWhy does Gradient Boosting regression predict negative values when there are no negative y-values in my training set?How to improve an existing (trained) classifier?What is effect when I set up some self defined predisctor variables?Why Matlab neural network classification returns decimal values on prediction dataset?Fitting and transforming text data in training, testing, and validation setsHow to quantify the performance of the classifier (multi-class SVM) using the test data?How do I control for some patients providing multiple samples in my training data?Training and Test setTraining a convolutional neural network for image denoising in MatlabShouldn't an autoencoder with #(neurons in hidden layer) = #(neurons in input layer) be “perfect”?