Loadpull in ADS - RF Cafe Forums

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kris
Post subject: Loadpull in ADS Posted: Sat Dec 31, 2005 12:54 am
Does any one have experience with the many loadpull templates in ADS. I just want to know what exactly is s11_rho and s11_center and how do you modify its default setting for your own simulation?? The default is s11_rho = .75 and s11_center = 0.0 + j*0.0.

Also, in the same templates the S1P_Eqn component has the value for its parameter S[1,1]=LoadTuner. What's this 'LoadTuner'? I mean when you type this in what is ADS reading/doing?? Thanks

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kris
Post subject: Posted: Mon Jan 02, 2006 1:47 am
Hi guys

Here is a pic of a Loadpull simulation of simple PA. Below shows the power contours. I am very new to this I don't have a whole lot of experience so please tell me if these contours remotely look right? The reason for my suspicion is that in ALL of the references I have seen in textbooks and other places all of the power contours are, unlike mine, to the left of the smith chart...mine are to the right and open the like "(" instead of opening the other way like in references ")". The reference system impedance is 50 as usual. Also, I am expecting the optimal load ipmedance to be actually higher than 50 Ohms since my output power requirement is very low (10 dBm). This question sounds really dumb but what can i do? that's the best way for me to ask to clarify my confusion. Anyone knows a reference/tutorial that talks about loadpull/power contours in simple terms....not too high level. Thanks guys!!

-kris

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Guest
Post subject: Posted: Mon Jan 02, 2006 11:27 am
You are coorect in your assumption about the load pull being to the left. Power amplifiers are normally comprised of fairly large devices and as result the impedance looking into the output is relatively low, hence the contors show to the left of the smith chart. Now, some devices are internally matched, therefore , what you may be looking at is a matched device. Cant say for sure since I donot what device isbeing plotted. Steve Cripps has written many books on power amplifier design, also, you may wat to google PA, or Load PUll to find other relative references.

Posted 11/12/2012

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