• Sara
    1
    hello everyone,

    I’m a bit stuck in the concept of load pull…



    I’m using ADS to model and tune a amplifier, my questions are:
    (regardless of stability)

    1- by loadpull, we simulate the effect of different loads on the performance of the system. Imagine I picked the load ZL which leads the amp to have the best performance.

    As I assume I should put this as the output load, but what I observe in the examples is that starting from this point, a matching network to 50ohm is put in the output…

    I agree to match to 50ohm, but the unclear part for me is that when we match to 50ohm, the amp sees 50ohm as the output so the performance is not what I expected??



    2- why normaly left half of smith chart is used to simulate arbitrary load? why I have not seen the right portion in any example?



    3- when I find a desirable load for fundamental harmonic (ZL)

    I think in the ideal case for 2nd and 3rd harmonic, would be to get the max reflection coefficient (=1) (or Zout=inf???)

    and most probably it would not be the case with that very ZL that I picked.

    so what would be the approach here?
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