Thank you for the reply. Part of the reason for having such a layout was that I wanted to use that particular inductor which has a wired footprint where the 2 pins are on opposite sides. So I will select a different inductor that doesn't require such a big pad.Designing a bias tee for 5A is not that simple.
You can test the high pass part and low pass (DC injection) part separately, to see where the issue is. Cut traces to disconnect the other path, and peel of copper if necessary.
For the DC path, you want an open circuit at your RF frequency. One obvious mistake is the large trace width there, which gives a lot of shunt capacitance at the input. This is in parallel to your 50 Ohm lines connecting the high pass section.
Thank you for the reply. Yes, 0.11mm is very tight and I am not sure how good their manufacturing process is. However, I did pay a lot extra for their controlled impedance option so...On top of these statements, due to very thin dielectric layer (0.11mm) you get very narrow 50 ohms transmission lines (0.17mm).
This makes the design very unpredictable due to extra parasitic inductances added to the filter circuit. In this situation, a linear simulator may not be enough, and an EM simulator is required. This in case that the PCB manufacturer can provide the requested trace tolerances (hard to believe that cheap manufacturers can do this).
I will desolder C12 and solder a test cable to isolate the circuit. Hopefully, that would give me a bit more information.
I meant shunt capacitance to ground.4) Your air coil sits close above some ground and will have a lot of shunt inductance.
Yes, these values were taken from a previous design. The next test boards I make will use values taken from this calculator https://rf-tools.com/lc-filter/ Got these values for a 1700MHz cutoff HPF.I would also check L2. That large 470nH value will have a self resonance below 1.8 GHz and behave very different from the ideal 470nH.
Hi BigBoss,10uH is an absurd value for 1.7-1.8 GHz @50 Ohm.It should around 47-56nH, not more.
Tapping a component on a Microstrip Line is not a good idea. A small snake coil then main choke coil will be a better solution like that.
The original requirement is 10A!Snake Coil=Meander Line.
3A is not enough for DC Current Rate ?
So you will make your own coil by hand using enameled copper wire.I think 7-8 turns over a 5-10mm core diameter air coil will serve you well.For more information, refer to coil calculator on the web.The original requirement is 10A!
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