UKnowWhat Post subject: Stability circles. Unread postPosted:
Tue Jun 21, 2005 4:14 pm Offline Lieutenant User avatar
Joined: Tue Jun 21, 2005 3:50 pm Posts: 3 I have a problem
in a paper design using NEC-34018 a GaAs HJ-FET with degenerating inductance
feedback for stability. At 1.2 Ghz, in my ADS simulation, the K factor,
the mu_source & load are all greater than 1. |S11| and |S22| are
all <1. Both my source & load stability circles cover the unity
circle completely. According to text book about stability with LNA,
I understand that for |S22| <1 (or |S11| for load stability), the
stability circle should not cover certain areas of the unity circle
let's alone cover the whole thing, hence my design is not stable. But
then why K & mu_source & load are all greater 1 (indicating
it's stable at that particular frequency). Am I missing something?
Top Profile Guest Post subject: Unread postPosted:
Wed Jun 22, 2005 1:27 am Never mind the question. Mine is unconditional
stable. I was confusing. No harm done. Top Guest
Post subject: Unread postPosted: Wed Jun 22, 2005 8:57 am
Exactly, everything inside the circle is stable. Top
Guest Post subject: Unread postPosted: Thu Jun 23,
2005 2:53 am If S11& S22 <1 then the area inside the
stability circles is the unstable one. You have to match your output
and input to the area outside of the stability circle.
Posted 11/12/2012
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