741 Op-amp LTSpice Simulation

Thread Starter

tphuogg

Joined Apr 24, 2021
19
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.

1619913331197.png1619913427050.png
 

Attachments

Papabravo

Joined Feb 24, 2006
16,832
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.
 

Thread Starter

tphuogg

Joined Apr 24, 2021
19
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.
1620286251378.png
1620286854386.png
Please help.
Thank you so much.
 

Attachments

ericgibbs

Joined Jan 29, 2010
13,660
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.
 

crutschow

Joined Mar 14, 2008
27,756
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.

1620321381964.png
1620321587171.png
 

Thread Starter

tphuogg

Joined Apr 24, 2021
19
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
 
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