LTspice simulation for the instrumentation balanced input using NE5532

[pbilous]

Hello everyone!

I am having trouble running simulation schematics that I created using LTspice. I used external code for the NE5532 opamp from this website: https://jeastham.blogspot.com/2011/11/adding-ne5532-op-amp-model-to-ltspice.html

For some reason the simulation does not appear to be working. There are no errors thrown, but the output signal comes out as a very small voltage.

I am new to this
Any help would be greatly appreciated!

Pavlo

 

[MarcelvdG]

Looking at the .png file, it looks like you are driving it with a common-mode rather than a differential signal.

 

[pbilous]

Fixed it. Everything works as it should now.

 

[pbilous]

When I try to do freq analysis it throws an error.

 

[stv]

You should include an "ac" voltage for the signal sources (in advanced settings "small signal AC analysis").

 

[pbilous]

You should include a "ac" voltage for the signal sources (in advanced settings).

That fixed it! Thank you!

 

[pbilous]

Not sure why, but the frequency response on the output looks horrible. I is totally fine before on the input of the last opamp.

 

[Mooly]

It is correct for how the sim is set up.

Two inputs, one 180 degrees out of phase but that doesn't apply to the '1' you added. Try making one of the AC Amplitudes a -1

 

[bohrok2610]

It is correct for how the sim is set up.

Two inputs, one 180 degrees out of phase but that doesn't apply to the '1' you added. Try making one of the AC Amplitudes a -1

Or add 180 as AC phase to one.

 

[pbilous]

It is correct for how the sim is set up.

Two inputs, one 180 degrees out of phase but that doesn't apply to the '1' you added. Try making one of the AC Amplitudes a -1

Thank you! That worked!

 

[Mooly]

Or add 180 as phase to one.

I'm not so sure that works for AC analysis. AC analysis does not even need the voltage sources setting up, you can set them as 'None' and just enter 1 and -1 for the Small Signal AC Analysis

 

[Mooly]

Thank you! That worked!

👍 excellent.

 

[bohrok2610]

I'm not so sure that works for AC analysis. AC analysis does not even need the voltage sources setting up, you can set them as 'None' and just enter 1 and -1 for the Small Signal AC Analysis

I edited my post. I meant add 180 as AC phase. That is meant for ac analysis.

 

[pbilous]

Here are all files with everything seems to be working correctly.

Attached is also NE5532 zipped model file - to be placed into ...\Documents\LTspiceXVII\lib\sub

 

[Mooly]

I edited my post. I meant add 180 as AC phase. That is meant for ac analysis.

This would work:

But this I don't think will. The '1' needs to be a '-1':

 

[bohrok2610]

You are still missing the "AC Phase" field. That is below the "AC Amplitude"

 

[MarcelvdG]

AC phase 180, AC value -1 or one source turned upside down should all work.

 

[Mooly]

Yes, that would work.

 

[Mooly]

You are still missing the "AC Phase" field. That is below the "AC Amplitude"

Oh that one 😀 There are just so many ways to do the same thing in LT.

 

[Mark Tillotson]

Surely you only need one voltage source anyway, just float it, there are DC bias resistors so it's not a problem.