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.