Four AD9695 on single ZCU102, Memory bandwidth problem

Question

Hi, 
 
 I want to connect our own custom board (with four ad9695 chips on it) to a zcu102 via fmc connectors and use IIO-Oscillioscope to capture the data from all links. 
 However, I checked p.25 of the zcu102 datasheet , the highest memory bandwidth that PS-DDR can provide is 17.6 GB/s. For our design, we need to receive all the data from four AD9695s with sampling rate of 1.25 GSPS. For each sample representing 16 bits (2 bytes) data, we need the memory bandwidth to be larger than 4*2*1.25G*2 = 20 GB/s, so we need to find out other ways to deal with this high-speed data. 
 Could you give me any possible solution for this? For example, the possibilty to also use PL-DDR, or use the on-chip memory? Or any similar fpga design would also be helpful! 
 I saw your employee also propose a possible solution for a similar case . But I'm not sure if that is possible for case. 
 
 Thanks in advance!

AdrianC · Accepted Answer

Hello, 
 We don't have an example of that, but in theory we have sync start option on the DMA so they should be able to transfer data. We've validated multi FPGA sync using this option so that works. 
 We are using the HP ports which have a maximum throughput of 330MHz@128bits which should cover one AD9695, which we use in our reference design. If you use two of the HP ports, it's possible that it would work but would need to be tested in hardware. I highly doubt 3 would work without losing data, but in theory it can be possible. 
 The PL DDR, with 16 x 2 x 2400 would give an interface of 300MHzx 256 bits which would not suffice for two AD9095 even at 100% efficiency of writing to the DDR(i'm not even sure if the PL DDR works at 2400, maybe slightly lower, as we don't use it in our design). 
 Regards, 
 Adrian)

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Four AD9695 on single ZCU102, Memory bandwidth problem