Calculated impedance matching network mismatch with provided in datasheet.

tretmax

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Hi all,

I am trying to build PA with RQA0009SXAQS transistor for 500MHz frequency and at this point trying to simulate output impedance matching network from datasheet s-parameters.

For 500 MHz(6V), S22 is 0.855 -173.8, that could be converted to 3.9 -j2.7, i plot this on Smit chart and got this impedance matching network.


Datasheet also include circuits example for different frequencies, but once i check example of output impedance network for most nearest frequency it is totally not fit into my calculations.
In example output impedance network for 520 MHz, overall capacitance could be nearly matched to my calculations, but inductor elements it is totally out, it is much less in provided example. This part not clear for me, as i understand both example calculations for ideal transmission line but difference is pretty big, how this could be properly simulated or should i just rely on my calculations.

Thank you!

 

Physical component size and routing effects can also add some nH, so I guess the ideal values differ from actual component values tweaked in the lab.
 

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