AFE7700EVM: Max data rate per lane and ADC/DAC data rate if run individually.

Hi Imran,

Max data rates supported by Rx ADC and DAC are 250MSPS and 750MSPS respectively.

Assuming 8b/10b encoding, if 4 ADC JESD lanes are used for 4 Rx ADC channels with 250MSPS output rate, JESD lane rate will be 10Gbps and if 8 DAC JESD lanes are used for 4 DAC channels with 750MSPS output rate, JESD lane rate will be 15Gbps.

AFE7700 also support higher JESD lane rates up to 24.75Gbps (in 64b/66b encoding) when configured to use lesser number of JESD lanes.

Regards,

Vijay

Hi Vijayandra,

I am planning to use this EVM card for JESD204C. can you please let me know for JESD204C (64b/66b encoding)?.

In AFE7700 Quad Channel General puprpose RF Transceiver datasheet, we are seeing, 8 SerDes transceivers up to 29.5 Gbps but you are mentioning that it will support upto 24.75Gbps. it is confusing. Is 29.5Gbps is per serdes lane rate or combine 8 serdes lane rate?.

We are planning to use only one lane at time for ADC/DAC, then what will be the maximum JESD per lane rate?.

Thanks,

Imran

can we use ADC only or DAC only from AFE7700EVM?. we want to run only ADC single lane from AFE7700EVM, then what will be the JESD lane rate for 64b/66b?. 

we also want to know if we run only DAC single lane from AFE7700EVM, then what will be the JESD lane rate for 64b/66b?.

Hi Imran,

AFE7700 supports lane rate up to 29.5Gbps per each SERDES lane. But 29.5Gbps is needed when using 8b/10b encoding. If 64b/66b encoding is used, max lane rate needed is 24.75Gbps. JESD standard recommends using 64b/66b encoding when lane rate is >16Gbps. That's why I mentioned maximum lane rate as 24.75Gbps. 

When using 64b/66b encoding and one JESD lane for 4 ADC data, if ADC digital output data rate is 187.5MSPS, lane rate will be 24.75Gbps. Note that instantaneous bandwidth is 80% of data rate. That's 150MHz in this case.

For example if 100MHz instantaneous bandwidth is enough for your application, you can use 125MSPS output data rate. Similar to above case, if one JESD lane is used for 4 ADC data, lane rate would be 16.5Gbps (assuming 64b/66b encoding).

The same calculations are valid for DAC as well.

Only ADCs or only DACs can be run with unused data converters turned off. 

Regards,

Vijay

Hi Vijay,

Vijayendra Varma Siddamsetty said:

But 29.5Gbps is needed when using 8b/10b encoding.

but can 8b10b go upto 29.5Gbps?. How to achieve this?

as you have mention

Vijayendra Varma Siddamsetty said:

JESD standard recommends using 64b/66b encoding when lane rate is >16Gbps.

then we should be able to achieve 29.5Gbps with 64b/66b.

we are planning to go for max JESD lane rate for our validation purpose.

Thanks,

Imran

in JESD204C Standard doc, table say 

for data rate > 16G, 8b10b not recommended.

Thanks,

Imran