Hi,
I am trying to plot frequency response of 741 op-amp by LTSpice. No matter I tried, I can't get the plot to be shown.
I am a newbie as I just started with LTSpice yesterday. I have attached the file below, please help me to inspect what did I do wrong.
Thank you so much.

 

You have to select the output pin with the cursor. When the hovers near a net on the schematic it changes from a white arrow to a red "test probe". If you Left-Click the mouse when it does this you will get the plot that you seek.

 

hi tp,
AC Analysis plot.
E

 

I fix the simulation for you:

 

Thank you so much

 

Hi I need help on my LTSpice project on the op-amp 741 frequency response. So far, I did the calculation by hand and plotted the function with MATLAB.

The problem is that I am not sure how to use LTSpice to simulate to have a similar output as the matlab one.


Please help.
Thank you so much.

 

Hi tp,
@jony Post #4 showed the LTS asc plot.
Is this a new problem.?
E

 

Hi tp,
@jony Post #4 showed the LTS asc plot.
Is this a new problem.?
E

Yes, this is another issue. Now I have to use LTSpice 741 model to plot low frequency pole and unity gain-bandwidth frequency.

 

hi tp,
Why have you not used the LM741 listed in the LTSpice Educational asc files.

E

 

hi tp,
Why have you not used the LM741 listed in the LTSpice Educational asc files.

E
View attachment 237568

It is a part of the project as I have to use the constructed LM741 to do the analysis.

 

hi,
OK, understood.
As it is a DC OPA, what do you think the Low Freq Pole will be.??

E
unity gain-bandwidth frequency.

Check the method in my post #9 image.

 

hi,
OK, understood.
As it is a DC OPA, what do you think the Low Freq Pole will be.??

E

I calculated low frequency pole = 3.8 Hz

 

hi tp,
Look at page #3 of this document.

You should also find the document useful for your future analysis studies.
E
http://in.ncu.edu.tw/ncume_ee/harvard-es154/lect_17_amp_freq_resp.pdf

 

hi tp,
Look at page #3 of this document.

You should also find the document useful for your future analysis studies.
E
http://in.ncu.edu.tw/ncume_ee/harvard-es154/lect_17_amp_freq_resp.pdf

Thank you for your help, I figured out

 

Here's one way to generate the AC open-loop frequency response, similar to the matlab plot.
It's connected as a non-inverting amp with DC feedback to stabilize the DC bias, but with a very large capacitor to ground in the feedback loop, to cancel the AC feedback.

For more accurate simulation of the 741, you need to use specific transistor models, not just use the default models.

 

Here's one way to generate the AC open-loop frequency response, similar to the matlab plot.
It's connected as a non-inverting amp with DC feedback to stabilize the DC bias, but with a very large capacitor to ground in the feedback loop, to cancel the AC feedback.

For more accurate simulation of the 741, you need to use specific transistor models, not just use the default models.

View attachment 237610
View attachment 237611

Thank you so much crutschow and ericgibbs. You are the best. I did very well with my presentation today with your help today