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I am designing a GPS module and I am planning to isolate the RF GND from the DC power supply GND with an inductor.

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I have chosen the Murata LQW18CN4N9D0ZD because the low inductance will have low Ldi/dt voltage spikes, it has a high current rating so I don't have to worry about the current draw for the GPS circuitry, and it has a resonant frequency above the 1.6 GHz range of the GPS signals, so the GPS signals will see it as a very high impedance.

My thinking behind this is two-fold.

  1. I will keep all RF related noise confined within the RF GND portion of the PCB and the DC power supply GND will not see it.
  2. I will keep any noise from the digital circuitry on the DC power supply GND out of the RF GND, but the DC component of the GND can flow into the RF GND easily.

I am a noob at designing for RF and so I don't know if this is a good idea or not. The GPS module does suggest to isolate the RF GND using vias, and I have seen AGND isolated from DGND with an inductor before in some designs.

I would like to know if you see anything wrong with this design approach and if you would suggest any changes.

humanistscience
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    It's difficult to predict whether you will need to isolate the RF ground from the DC ground in this way. What you're doing is prudent, but before soldering the inductor, you can solder in a 0 ohm, 1608 resistor to those pads. Test your circuit. If it works, you can save the cost of the inductor in your design. If not, it's easy to unsolder the jumper and install the inductor. – Mark Leavitt Apr 21 '22 at 23:51
  • Thanks so much again for your help. I have posted a question on differing design rules for the RF traces from different sources, and would appreciate your thoughts on the question. https://electronics.stackexchange.com/questions/616827/antenna-feed-trace-keep-it-short-or-long – humanistscience Apr 22 '22 at 02:42

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