Frequency domain simulation issue with phase response SOLVED

I tried to explore the changes to the frequency response of simple passive RC low pass filters when a second and third cascaded filter section is added.

Unexpectedly, the phase response of the 3rd order filter shows a "jump" in the output.

Why is this?

NB: Please ignore the OpAmp in the circuit.

by Dan.Ka
November 11, 2020

Perfectly normal. When the phase becomes far enough lagging it is leading

by Foxx
November 11, 2020

So you are saying it's just the presentation style of CL's graphing engine. Fair enough.

I prefer, however, the graphing engine to draw phases below - 180° in the negative axis region, as for example here:

by Dan.Ka
November 11, 2020

Yes it's CL's presentation. I have no problem with it once I figured it out

by Foxx
November 12, 2020

1 Answer

Answer by mrobbins

@Dan.Ka This has been fixed now. See blog post: Complex Numbers, Math.atan2, and Phase Unwrapping

ACCEPTED +2 votes
by mrobbins
November 30, 2020

Thanks. Looks much better now in my opinion.

by Dan.Ka
December 01, 2020

And additionally a great blog positing explaining this change. Perfect!

by Dan.Ka
December 01, 2020

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