please reply---output match in PA - RF Cafe Forums
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Post subject: please reply---output match in PA Posted: Sun Jan 08, 2006 2:22 am
i know i've been asking a few questions and i really appreciate all the answer....i'm a student learning and i've one more question to ask.
i did loadpull analysis and i found out that I need a load of X+jY. so what i did i just transformed a 50 ohm load to X+jY using the matching utility in ADS and it seemed to work. now when i put it in the circuit it doesn't match all that well. when i am running s-param simulation i terminate in 50 ohms since i'm transforming 50 ohms to X+jY, right? if not please explain how a match can be verified for optimal load match? Just wanted to make sure. the thing that is confusing me is that the output is taken from the collector and there is a certain output impedance....if you were doing the usual conjugate match then it is clear to me but here it's not conjugate match but instead the transistor needs to see a certain load (X+jY) and i do that by transforming 50 ohms to this X+jY value...because of this i don't understand what the output reflection coefficient is calculating or reprsenting?? the thing is if i try to tune the components of output match in ADS then this would eventually lead to "conjugate match" and not a match to X+jY because as I said the output is connected to collector and after a matching network is terminated in 50 Ohms.
also the way i did output match was to take the X+jY impedance and then do the usual standard method of matching 50 ohms to X+jY...this is how you do it, right? please reply, your help will be very much required