clock problem

Hi UVLSIDRIVER 

Thanks for using AD9082.

I move this thread to the proper forum. Someone here can assist you in your query.

I wonder how it ever worked without external off-chip filter if you use internal PLL multiplier since off-chip filter is reuqired as stated in the user guide. Could you modify your software/hardware to bypass internal PLL and use external clock to feed DACCLK and ADCCLK? That'd confirm whether issue is related to interal PLL, and you will have to modify the hardware if that's the case. 

Hello,

we will try external clock and come back with update.

Best regards

Hello,

Currently, we have not tested the system with an external clock. We plan to focus on debugging the clock path. Regarding the issue of the DAC and ADC outputting zeroes, we've identified that the AD9082 PLL sometimes fails to lock, preventing the AD9082 initialization from completing successfully..We observe that clock that is given as device clock for ad9082 when we read the frequency we should ideally get 387.5mhz but in some cases we are getting 1664khz due to which our PLL is not getting locked. Why does HMC7044 is producing different clock than specified in some power ons.
I think due to irregular clock out from HMC7044 we are facing the issue. How can we fix this?

We are using the project extracted from GitHub.Our configuration is sampling rate is 1500msps and clock is 387.5Mhz for both adc and dac. 

Best regards,

Hello,

Could you please provide an update on this? We are currently at a standstill and unable to proceed without resolving this issue.

Best regards

It sounds like the issue is with HMC7044 rather than AD9082 if the reference clock from HMC7044 to AD9082 is not stable. Could you confirm it by reading the lock status of PLL1 and PLL2 of HMC7044 when the reference clock is unstable? 

Thank you for sharing the data. There seem to be multiple issues. Firstly, the behaviour of the AD9082 chip without external off-chip filter is unpredictable if internal PLL multiplier is used. And it appears that HMC7044 also has an issue. I suppose these results are from your custom hardware, and would it be possible for you to try with ADI reference evaluation board?