LMX2594EVM: Synt is not locked @ 9.75GHz , 85 deg (Oven test)

Hello,

The settings displayed have no obvious configuration errors.

I would suspect that the issue lies with the external loop filter components, potentially a leakage path or partially shorted component. As the loop filter is disconnected when the VCO calibration is conducted this would not be seen during VCO cal. 

Please verify the voltage at this node and the connections for the external capacitors.

Regards,

Thanks i'll check soldering quality.

The loop filter values are

Res 33, 47 ohm

Caps 2.2, 330 , 1.5nF

Can your assumption also explain why 10.6GHz

And 12.8GHz are ok at same conditions and only 9.75GHz fails to lock?

i also saw that the freqs below 9.7GHz and above 10.2GHz are ok at 90 deg but 9.7-10.2 are not able to be locked , the PFD delay sel is 3, VCO3 at 304 start amplitude

Hi Arye,

I don't know what went wrong, something you can try:

1. Do integer channels also have problem? for example, at 9700MHz, 9800MHz, etc.

2. Change CAL_CLK_DIV to "Div2, Fosc<=400MHz"

3. Were you start locking the part at 25C and then cycling the temperature? Can you try start locking it at 85C?

Hi 

i started locking at 85C

8000 , 8100, ...9500, 9600 MHz ok, 

10200,10300....ok

9700, 9800, 9900, 10000, 10100 not ok

Hi Still unsolved, do you think i need to replace the Synt on the evb? will it help?

do you think i need to buy new EVB? 

do you have rep. that could explain me on the phone?