Phase noise measurements with the Koheron ALPHA250

We released a new FPGA design for phase noise measurements.

Using a Koheron ALPHA250, we compared the phase noise of 40 MHz signals from 3 different noise sources: a Red Pitaya STEMLab 125-14, another Koheron ALPHA250, and a 120 MHz signal generator (Keysight 33622A):

The higher phase noise of the Red Pitaya can be explained by the fact that the Red Pitaya DAC is clocked from a phase-locked loop inside the FPGA, instead of an external PLL.

The source code is available on GitHub for the ALPHA250 and the Red Pitaya.