AD9747 + interposer trouble

What are you trying to do? Why are you probing J3 for output? Read the hardware setup again.

Sorry if I was unclear. I connected the scope to IOUT1P and IOUT2P (J5 and J9) and saw nothing. Then when trying to debug to see if anything was running, I tried to check the output clock (J3), and was surprised to see no output clock, irrespective of the SPI settings. Perhaps this is not useful information but I was trying to provide as much information as I could.

That is okay- thanks for explaining, Larry might be able to give you more information about that output.

Have you tried to connect the clock input to J4 ?

I will trace the clocks first, you should be seeing something if the clock is running.

Thanks. Well as I said in my original post, I checked the jumpers JP2 and JP3 and they're unpopulated so I assume J4 will not be of any use. I believe I did try it anyway as a last resort, but to be honest I can't remember. I'll give it another go when I'm back.

Hi -

What do you at the following points on the EVB?

TP16 - REFIO

JP16 1-2 DCO clock output

J5, J8 - DAC outputs (J7 and J9 are grounded)

JP6 2-3, IOUTP1 at DAC

JP5 2-3, IOUTP2 at DAC

TP1, TP3, TP5, TP7, TP9, TP11 - power supply outputs

Thanks,

Larry

Thanks for the response Larry. I'm afraid I have only just come back to this project, hence the delay.

TP16: 1.20 V

JP16: 3.6 V 10.42 MHz square wave (this seems low?!  250MHz / 24)

J5, J8 I see nothing through the small amount of noise.

JP5 and JP6 I've attached images from the scope below.

TP1: 1.84V

TP3: 1.84V

TP5: 3.34V

TP7: 3.33V

TP9: 3.31V

TP11: 4.96V

JP5:~1.9MHz

JP6: ~1.3MHz

So it seems there are two problems:

Problem 1: The clock is being divided by 24 rather than bypassed.

Is this likely to be my error using the SPI software? Are there any tricks to using it?

I can power down DAC1 and DAC2 using the 'Power Down' tab for example, however using the 'AD9516-DAC Clock' tab, neither of the Bypass checkboxes seem to have any effect.

For my purposes, I don't ever expect to need the AD9516. Would it be reasonable to switch JP2 and JP3 to connect to J4 and use that as a direct clock input? If so, is there anything I need to do to disable AD9516?

Problem 2: The output is shown at JP5 and JP6 but not J5 and J9.

I don't have a multimeter today and will have to wait for Monday if I need it. However it should be possible to figure this out from the schematic. I would expect (for example let's look at DAC1) that JP4 and JP5 be connected between 'Com' and 'B', to send the output through T5 and T7 to J5. On my board they are connected to 'A' which looks like it goes to the modulator output (however I still see nothing at the modulator output).

Should I just change the soldering on JP4, JP5, JP6, JP7? Is anything else necessary? I wonder if this error occurred only on my board.

One final observation when I looked closely: in the schematic R40 is connected to J8, and R41 to J9. These are reversed on my board, although I keep confusing myself with polarities trying to figure out which one is wrong, so I'll leave that for now!

Anyway, thanks for advising me what to look at. If you could let me know about the clock input, and confirm I can switch JP4-7 to get direct SMA outputs, I'll mark this as Answered!

Hi -

It sounds like JP4, JP5, JP6 and JP7 are configured to route the signals to the ADL5375 QMOD rather than J5 and J6.

The attached qucik start guide should help with AD9516 settings.

Thanks,

Larry

Sorry I forgot to reply earlier. I resoldered the jumpers to connect to J5 and J9 to get the output working correctly.

I never solved the issue with the clock divider, but I am using a direct clock input on J4 instead after soldering JP2/3 appropriately.

Thanks again for the help.

Great