source pull simulation and input impedance match

shanmei said:

Thank you for your reply. View attachment 153282

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shanmei said:

The Zo in the red cycle is always there, and the blank space after it is not for entering the Zo. It is for the Zs or ZL input.

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BigBoss said:

In your matching template, the center of the Smith Chart has 5.5+j*2.8 Ohm, so you try to match an impedance to this value then you drive your amplifier with 50 Ohm source impedance.
So, there is no match at all.. You have to match this impedance 5.5+j*2.8 (whatsoever) to 50 Ohm.

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circuitking said:

In the smith chart utility tool it says ZS* and you entered 5.5+j*2.8. That means if you see the impedance at the input of the extracted matching network, you get 5.5-j*2.8 ohm. So your transistor sees 5.5-j*2.8 ohm.

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I would like to know is it always necessary to keep 50 ohm in ZS*. We can also do like I said above right?

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circuitking said:

Somebody tell me why is it says ZS*, instead of Zs?.

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pancho_hideboo said:

Simply conjugate matching.

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circuitking said:

Then in that case, in the smith chart utility If I enter ZS* as 5.5+j*2.8
and build the circuit, the impedance looking at the input of the extracted matching network should be 5.5-j*2.8 ohm.

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circuitking said:

But I get Zin as 5.5+j*2.8 ohm.

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pancho_hideboo said:

Zs=5.5-j*2.8, Zin=5.5+j*2.8=conj(Zs)

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