Part Number: LMX2492
Hi All!
We have a problem with LMX2492 evaluation board. The setup is:
1. Fosc = 100 MHz
2. Fpd = 100 MHz
3. Fvco = 9600.1 MHz
4. Third order Modulator
5. No dithering
6. CPG = 31
Integer part of divider is 96 and fractional part is 1 / 1000.
Looking at the output signal we see spurs occuring at Fvco % Fpd frequencies:
And the spurs are very large (-10 dB) compared to the simulation results from PLLatinumSim (-60 dB).
Decreasing charge pump current lowers these spurs by another 10 dB, but they are still far from our expectations.
When using LMX2492 as integer only PLL, the result is perfect.
This is expected behaviour for this PLL or we have something wrong with setup?
Yurii
