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Update to latest version LibreCAL A+ 2023-02-01 #8
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…ed for Visual Studio 2019 Qt5.15.2 static build)
Optimized RF Traces for JLCPCB 4Layer JLC04161H-7628 Stackup with CPWG Z=50 Ohms Track width 0.34mm, Conductor Gap 0.2mm Changed 50 Ohms Load Part from CH0402-50RGFTA to CH0402-50RGFPT
…ion of RF Loss on each RF traces
Hi, thank you for the changes.
Do you have any data to back up that this is actually an optimization? I have gotten pretty good results with 0.3mm width and 0.18mm gap so far.
I am contemplating switching back to a generic 50 ohm resistor here. I have measured cheap (0402) resistors as 30dB return loss all the way to 6 GHz and it won't get any better than that due to the return loss limits of the switches (and probably the transition from connector to PCB trace). I just don't think these expensive resistors are worth it here.
That looks rather useful. Is it generated by KiCad or have you created that yourself? |
I have computed them with Saturn PCB Design PCB Toolkit V8.22
The main advantage of RF 50 Ohms Load is the stability of the Impedance which is always the same even after 20GHz maybe it is not mandatory for the eCal.
I have extracted the length of Tracks from KiCad then exported them in LibreOffice Calc which compute the estimated RF Loss for FR4 using 0.3 FR4 Loss in dB/cm @6GHz (which is quite good and based on https://www.edn.com/loss-in-a-channel-rule-of-thumb-9/) |
…st and createFactoryCoefficients_Test.py to test the LibreCAL Firmware with dummy data and different test cases
Thank you very much for the additional feature :) But would you mind putting it in a new PR? I don't think I am going to merge the hardware changes, I'd like to keep my 0.3mm trace width and 0.18mm gap. I am aware that these values are not ideal if you plug them into a calculator but I got good experimental results with that and am very hesitant to change that. (I can also try to cherry-pick if it is too much work to move this to a new PR) |
I understand your point as you prefer to keep your hardware version (that you have manufactured & validated on your side). |
It is a minor update just to reflect my latest changes on my 5 produced units (in test waiting aluminum cases to fully characterize the boards with my HP 8753D VNA on 4ports from 30kHz to 6GHz)
Tell me if you are interested in those modifications / improvements else just tell me you do not want them and I will keep that in my own branch for reference with my small 5 boards production batch