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Sx_cut

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Posts: 16
Dresden, Germany

Read-out for High Speed ADCs
Apr 10^th, 2016, 8:26am

Dear all,
In order to acquire linearity and SNR plots for the ADC we typically require hundreds of thousands of sample points (depending on resolution of ADC). Usually people have large on chip memories to deal with such massive amount of data. They dump the data in memory and perform read out at a slow rate (Memory write is still limited to around less than 1GHz so high speed ADCs are usually interleaved).

The problem is I don't have the luxury of having a memory at the moment and I have to rely on high speed IO for that matter. I am new to high speed IOs, so can you tell me what IO architectures can I use with my ADC with data output rate of 1Gbps? FPGA will serve as data acquisition instrument.

Simply put, any thoughts of how to handle massive 32 bit data coming out of ADC at 2Gbps?

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DanielLam

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Re: Read-out for High Speed ADCs
Reply #1 - Apr 12^th, 2016, 1:02am

Is the chip already made? Can't put together 32->64->128 Dffs?

You should check how fast the FPGA can read data. I am guessing < 500 MHz. So you will need a small memory, otherwise you can't run your ADC at 2 GS/S.

Unless, are you thinking of high speed IO and putting that data into memory on the PCB? Then grabbing from PCB with FPGA?

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RobG

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Bozeman, MT

Re: Read-out for High Speed ADCs
Reply #2 - Apr 15^th, 2016, 7:44am

Sx_cut wrote on Apr 10^th, 2016, 8:26am:

Dear all,
In order to acquire linearity and SNR plots for the ADC we typically require hundreds of thousands of sample points (depending on resolution of ADC). Usually people have large on chip memories to deal with such massive amount of data. They dump the data in memory and perform read out at a slow rate (Memory write is still limited to around less than 1GHz so high speed ADCs are usually interleaved).

The problem is I don't have the luxury of having a memory at the moment and I have to rely on high speed IO for that matter. I am new to high speed IOs, so can you tell me what IO architectures can I use with my ADC with data output rate of 1Gbps? FPGA will serve as data acquisition instrument.

Simply put, any thoughts of how to handle massive 32 bit data coming out of ADC at 2Gbps?

You could sub-sample the output (i.e. output every other data point). The result will be an aliased version of the ADC output but you can account for that mathematically. I guess this is commonly done for papers. You could also use twice the number of outputs working at 1/2 the rate.

I'm not sure why you are outputting 32 bits.

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