Matching Circuit Tool generates wrong results #905
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Hi @tomhajjar , thanks for pointing this out. The device is not unconditionally stable and it cannot be conjugately matched. Equations 12.40a/b in [1] don't have a solution for this case since the argument of the square roots is negative.
I think that the best solution would be to check if the device is unconditionally stable here in order to avoid wrong results like this. I can write a fix for this later. Schematic: [1] Microwave Engineering. David M Pozar. 4th Edition. 2012 |
As reported in issue ra3xdh#905, the matching network tool gave wrong results when using a conditionally stable S-matrix. In order to have a conjugately match, the device is required to meet the unconditional stability criteria defined in [1] as K > 1 and abs(delta) < 1 A condition was added in the program to filter out these cases and warn the user against this limitation. [1] Microwave Engineering. David M Pozar. 2012. Eqs 12.28 and 12.29
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Not often a device's Spice model correlates so well with it's S-parameter data...
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One minor issue with the tool is if any entry or setting is "wrong" or out of bounds, a error message is shown and the tool is closed. Is there a way to allow the user to fix the wrong entry and not close the tool? |
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Good point. I'll take a look later. |
…K_less_1 Fix issue #905 - The matching network tool gives incorrect results when conditionally stable data is provided
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Fixed by #907. Closing as completed. |
A condition has been added to slotButtCreate() to keep the dialogue open in case the synthesis goes wrong. This allows the user to fix the input parameters as requested in issue ra3xdh#905.
Fixed in PR #909 |
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This Qorvo tool is useful for seeing the effect of R on K.
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Update:
The device seems to be marginally stable.
Project updated with all fixes
Follow up to #401, @andresmmera
In testing Matching Circuit Tool for an "L-section match" case, I found the component values to be unrealistic.
The input match L1 shunt inductor value of "0.000H" should be interpreted as a short to ground or possibly using "creative license", an open circuit to ground. The output match L4 series inductor value of "2.556H" can only be interpreted as an open circuit.
I didn't test any other cases since having to copy and paste S-parameter values becomes tedious and error prone.
BFP193W_amplifier_prj.zip
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