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MKW21D design questions

Question asked by Ben Hefner on Oct 13, 2016
Latest reply on Oct 17, 2016 by A_Quiroz

I'm working on a PCB layout using an MK21D part, and I have a few questions about the design.


First, is there a more stripped down reference design available than the FRDM board schematic? Something with just the minimum for chip support and wireless comms?


Second, what do I need to do with the TAMPER pin if I don't want to use it? I didn't see this in the reference manual.


Lastly, I'm pretty new to RF design, so I have some more general questions about it.

  • How critical is controlled impedance on a transmission line (with a chip antenna)? Does anyone know roughly how bad an uncontrolled PCB could be if I had the trace and board stackup correct? Is it just the fact that it's not controlled? Any idea what difference there might be in cost?
  • What changes would I need to make in the design if I wanted to use a surface mount chip antenna
  • Is there a more integrated balun available? What do I need to know to search for one?


Any guidance I can get would be appreciated.