Tuesday, 16 July 2013
DATV-Express Phase plots
synth used by the ADRF6755 PLL/Modulator. The light blue trace at
the bottom is the base reference for the Agilent E4406A used to make
the measurements. However it is at 50 MHz so not that representative.
In fact at frequencies below 10 KHz and above 1 MHz it looks as if
the phase noise from the Agilent may well be dominating the plot.
These plots were done using John KE5FX's PN software.
The results are within a few dBs of the equivalent trace in the Analogue
Devices data sheet. The above trace has spur removal activated. There
were 3 main spurs within the loop filter bandwidth that I could see.
The first was at 50 Hz (UK mains frequency), the next at 150 Hz and the
last at 5.5 KHz, this last spur is probably related to the divider/charge pump
in the PLL as it changes with frequency in a very predictable manner.
None of the spurs exceed the manufacturer's data. All these traces were done
at 1.2 GHz to match figure 27 in the data sheet. The ADRF6755 was silicon