We made X-Band driver module(LO 6.95GHz). Its heterodyne is based on Minicircuits ROS-3550 VCO and ADF4153 with frequency doubling.
Our client made temperature phase hits test with temperature change velocity 2degrees Celcium per minute. In this test it discovered that when cooling the unit many comunication errors are obtained in closed modem loop. Than a phase change velocity test was performed it showed a result
Reference signal signal is 10MHz. It is filtered in unit by HPF(5MHz cutoff frequency) and than amplified by 2 cascades on BC817.
We tried to change synthesier to ADF4106 but nothing changed. We discovered that most sensetive elements for temperature hits are synthesier and VCO
The question is what can give such phase change velocity and how to deal with it?