FMCOMMS3 Configuration Options

The AD-FMCOMMS3 has almost no configuration options for normal use. If you find that this platform does meet your RF performance goals, you should check out the ad-fmcomms2-ebz board, which can be tuned with external baluns.

Changing the external clock

The AD-FMCOMMS2-EBZ and AD-FMCOMMS3-EBZ are both clocked from a 40.000000 MHz Epson crystal. If you want to run from a external source, you need to remove Y101, populate C113 (0.1uF Cap), and provide a low jitter clock source into J105 (SMA connector). If you provide anything but a 40.000000 MHz input, you are required to change the clock-frequency setting in the device tree.

<source /arch/arm/boot/dts/adi-fmcomms2.dtsi:clocks{} c linux/master>

To change the frequency follow this guide on how to build the devicetree binary file (make sure you modify the clock-frequency attribute first.)