I have a design with 8 ADRV9009 ICs. AD9528 is the clock chip used and it provide clocks and SYSREF ADRV9009 and the FPGA GT banks. We need all ADRV9009 ICs to have phase sync so the clock inputs must all be aligned.
These 8 ICs are present on one radio card. There are 4 such cards in the system, so the an input GLOBAL CLK is fed into each card.
Below are two possible clocking schemes, which is better/suggested?
Option 1 will be better. One AD9528 has 14 outputs. " The AD9528 can also be used as a dual input flexible buffer to distribute 14 device clock and/or SYSREF signals "
So for 8 Transceiver +…
In both options, AD9528 is used only for fanout in PLL bypass mode.
In option 1, 4 AD9528 ICs are used (instead of 3) to make placement and routing easier and convenient. The advantage of option 1 is that layout is simplified. In option 2, the symmetric placement of the input stage AD9528 is a bit difficult.
The problem with option 1 is that I don't know what are the timing requirements for the forwarded clocks. The clocks that go to the radio ICs and the FPGA should be length matched for phase sync and the SYSREF should meet timing. But what about the forwarded clocks. To what should they be length matched, what are the timing requirements to ensure that all ADRV9009 ICs are in sync.
Which option is better, 1 or 2?
So for 8 Transceiver + FPGA you need only 2 AD9528. For second AD9528 you can bypass PLL2 to avoid offset because of second VCO.
You can adjust the delay in first AD9528 such that all the DEV_CLK's (from both AD9528) are reaching the transceiver at same time.
Thanks for the reply.
I have also Question for external clock
We are using ADRV9009 evaluation board with ZCU102. IIOSCOPE works with Example design, no matter we connect external clock source or not.
1- Is it normal for the system to work without external clock?
2- We want to use external clock (30.72MHz). How can we be sure that system is working on external clock when we connect it. UG-1295 points to a setting in TES GUI (Fig 61) to enable external LO, but TES doesn't work with ZCU102. In IIOSCOPE, we could not find a relevant setting.
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