The Designer's Guide Community
Forum
Welcome, Guest. Please Login or Register. Please follow the Forum guidelines.
Sep 19th, 2020, 11:33am
Pages: 1
Send Topic Print
stability for ckts having one feedback and one forward loop (Read 58 times)
tulip
Community Member
***
Offline



Posts: 37

stability for ckts having one feedback and one forward loop
Sep 4th, 2020, 8:05am
 
I designed a circuit having one feedback and one feed forward loop, the feed forward loop is used to provide a zero to improve the phase margin of the feedback loop.
When I break the feedback loop, the stb analysis shows the loop is stable, but when I break the the feedforward loop, the stb analyais shows the loop is unstable.
The transient reponse of the circuit is stable.

In cadence help file "spectreref.pdf", it says: The  loop-based algorithm can only be performed on individual feedback loops to ensure that they are stable. Although the stability of all feedback loops is only a necessary condition for the whole circuit to be stable, the multi-loop circuit tends to be stable if all individual loops are associated with reasonable stability margins.

Does cadence mean that if one of the loop of a multi-loop circuit is unstable, the whole circuit is unstable?
How can I check the stability of the circuit I designed?

Thank you very much.
Back to top
 
« Last Edit: Sep 05th, 2020, 5:11am by tulip »  

Not every morning wake up your alarm clock, but dream!
View Profile   IP Logged
Pages: 1
Send Topic Print
Copyright 2002-2020 Designer’s Guide Consulting, Inc. Designer’s Guide® is a registered trademark of Designer’s Guide Consulting, Inc. All rights reserved. Send comments or questions to editor@designers-guide.org. Consider submitting a paper or model.