2-Layer PCB for RF?

Discussion in 'General Electronics Chat' started by JeremyB, Jul 30, 2012.

  1. JeremyB

    Thread Starter New Member

    Jul 22, 2012
    Without power and ground planes, the power distribution network of a circuit board can become quite noisy due to insufficient decoupling. For some designs this does not matter much. But my design includes circuitry for wireless RF communication and other sensitive analog circuitry and I would like to know if it is a bad idea to use a 2-layer board.

    Board contains: AC-DC switching power supply (discrete), PIC microcontroller, PIR sensor (analog), thermistor (analog), relay, rf transceiver, antenna.

    Board size does not allow for ground plane or power plane of any kind. Power and ground must be run from point to point.

  2. kubeek

    AAC Fanatic!

    Sep 20, 2005
    If the RF is self contained module then it should be doable, as long as the module is properly shielded.
  3. JeremyB

    Thread Starter New Member

    Jul 22, 2012
    The RF circuitry is not a self-contained module but will be shielded.
  4. crutschow


    Mar 14, 2008
    If may work if you make sure all the RF grounds are close together and tightly coupled with large traces. Even better would be a small RF ground plane (flooded ground) under and around the RF circuitry.
  5. JeremyB

    Thread Starter New Member

    Jul 22, 2012
    OK thanks. Yes, I did plan on flooding a local RF ground plane. It seems reasonable to think that it could perform well with that.

    Thank you for your responses.
  6. takao21203

    Distinguished Member

    Apr 28, 2012
    If you use a dc/dc, then eventually you need a secondary L/C filter.
    I have run into problems a lot of times using dc/dc supplies for microcontrollers, especially having display as well + analog components inside the circuit.

    Adding extra LC filters has always been successful so far to make circuits working.

    If you don't use a LC filter, and try to run a complex circuit using a dc/dc, chances are high it will actually not work correctly. In some cases, spurious voltages will build up after some hours.

    L/C filter maybe sounds dramatically however, often just any kind of toroid core with some turns wire is sufficient, eventually a small capacitor as well. For low currents you only need RF coils, for instance 330 uH.