I have 2 questions and any help is appreciated.

The frequency is at 5.5 to 6 GHz range. RF trace impedance is 50 ohms.

  1. I have a resistive splitter to split RF signal into 2 traces with 6 dB attenuation. What is the correct way of placing the Zo/3 ohm resistors on the PCB? I placed R31, R32, and R33 as below with T like orientation. Would it be any better if I move R31 and R32 to sides and put R33's pad right between them? What is the most correct way of placing these 3 resistors?

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  1. I want to add u.fl connectors at some stages of RF signal path next to RF trace for debugging purposes. I learned that 0 ohm resistor or 10-100 pF capacitor can be used. Is there any difference between splitting with 45 degree or 90 degree angle? Right connector's trace is split using 0 ohm jumper resistor with 90 degrees angle to PCB antenna's RF trace. Is that ok or could it be better if the angle between traces have an angle like mitered bend? Because when I solder 0 ohm to select u.fl connector then the RF signal will see a 90 degree corner which is not recommended.

enter image description here


While the alternatives you're considering will affect the performance slightly, the differences will be small.

On the signal splitter, there's not a lot you can do about that triple pad in the middle, it's probably as good as it can be without proper design as it's shown. You could probably improve the performance slightly with some detailed modelling and measurement, but with 6dB loss, would you notice? You'll be using physically smaller components, with pad width commensurate with the line width, if you are serious about improving the performance.

If that is really a signal splitter, so one into two, then you may be better off with a 2 x Z power divider, rather than a symmetrical 3 x Z/3, it should be easier to tweak up the design performance if the loads are suitable.

The difference between 45 and 90 degree bands will be much less than simply going through the connector. It's a debug connection, so you will be making allowances for the uncertainties in your measurements.

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  • \$\begingroup\$ Thank you Neil_UK for answer. For second question, since that connection is for debugging, the purpose is to see what is going on for that trace so 45 or 90 degree will not affect much to understand if that rf stage is behaving as expected or not if i understand you correctly. Is this correct. \$\endgroup\$ – nandflash1 Sep 24 at 18:47
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    \$\begingroup\$ I'm not sure what your comment is asking, other than, yes, you will be able to see what's happening in your IC stage whether you have a 45 or 90 degree bend, within the tolerances you would expect anyway for going through a UFL. Personally, if I don't need the full power for measurement, I tend to use a 500 to 1 kohm 0402 'pickoff' resistor in series with the 50 ohm line to the UFL. This does not reduce the signal in the main line by much, and allows monitoring of the circuit in actual operation, at 20 to 26 dB below the main line signal. \$\endgroup\$ – Neil_UK Sep 24 at 20:23
  • \$\begingroup\$ I understand thank you. \$\endgroup\$ – nandflash1 Sep 25 at 7:41

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