User's Guide

Review Copy 11-6-10
ThingMagic Micro Family Guide
14
www.JADAKtech.com
There is the potential for 24 MHz harmonics (signals of a frequency that are an integer multiple of 24 MHz)
to radiate from pins 22 through 28 of the Micro. If emissions testing shows such harmonics, the easiest fix
is to put bypass capacitors (typically 39 to 100pf) directly at the offending pins on the carrier board. Note
that higher values are not necessarily better. At these frequencies, capacitors have both inductance and
capacitance, and the ideal capacitor value will have series resonance near the most offending frequency.
Therefore, it will look more like a short circuit to the frequencies around 900 MHz than its value would
suggest. 39pF has been good for around 900 MHz in sample board layouts.