Avoid PC-Layout \"Gotchas\" in ISM-RF Products

By: Martin Stoehr

Abstract: RF products for industrial, scientific, and medical systems (ISM-RF) often feature very compact circuitry. To avoid common design pitfalls and \"traps,\" the PC-board (PCB) layouts for these applications warrant careful attention. Operating in the various ISM frequency bands between 300MHz and 915MHz, these products include receivers and transmitters whose RF power levels range from -120dBm to +13dBm. Topics in the following discussion include inductor orientation, trace coupling, ground via problems, trace length issues, ground plane usage, crystal capacitance, and trace inductors.