Post subject: Loadpull in ADS Posted: Sat Dec 31, 2005
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 +
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
Post subject: Posted: Mon Jan 02, 2006
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!!
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.