Lattice XP2 Brevia Dev Kit - How to Connect an parallel ADC?

Question

Have some of you an example "How to Connect an parallel ADC to the Lattice XP2 Brevia Dev Kit"? It could be parallel ADC 10-16 bit, 20 MSPS or higher. Thanks in advance!

michaelkellett · Answer

Here is a schematic of how to connect the AD9200 to the Brevia - I don't think this will work on prototype boards because you need a physical layout good at 100MHz or more (because of the bandwidth of the amplifier) . The AD9200 really needs an additional buffer amp for biasing which I have shown here. All the capacitors are 0603 surface mount except the two 10uF which are 0805. If you are still interested let me know and I'll lay out a pcb. To build it you'll need to get some pcbs made but from OSHPARK or similar they won't be very expensive. R2 loops an FPGA pin back to one of its PLL inputs so we can generate an FPGA clock at a suitable frequency. MK

michaelkellett · Answer

For the benefit of others I've suggested that Mira bring his problem here so that he can benefit from the wisdom of the E14 collective ! I've already suggested the Analog Devices AD9200 Farnell sell the AD9200JRSZ AD9200JRSZ for£3.02 for one This is the 0-70C version in 28 pin SOP package It's quite an old design(pre 1999 but has some interesting spec features 10 bit 20 MHz max sampling rate 300 MHz sample and hold (which means it can be use din undersampling mode to look at signals with frequencies above 20MHz) Parallel interface Cheap As is usual with parts from Analog Devices there is a lot of useful background information in the data sheet and it is well worth studying it carefully. AD recommend using an AD8041 op amp to drive the ADC input and this is also available from Farnell in DIP or SO packages. We can use the same 3.3V supply for the ADC and the Op Amp and we'll go for a +/- 5V full scale input range. In order to use these parts you can use surface mount adapter boards Farnell do the Roth range so we could use RE931-05 RE931-05 at£5.14 and RE932-01 RE932-01 for the op amp at£3.52 It would be much nicer to design a pcb but then you would need to get some made which will cost some money and take a little time. Because the parts need to work at high frequencies I would go for a pcb - fast delivery double sided boards 50mm square would cost me £37.80 for 1 board, 24 hour production. The Roth prototype board construction will save about £30 but is much harder to get right (lots of messy wires and little components hanging in the air). I don't have time do any more on this right now so please reply and let me know if you would rather a design based on a proper pcb and if the +/- 5V range is good. Once we have a physical design it's possible to work on the FPGA logic - actually you have to think a bit about that as you do the circuit so you don't end up using pins on the FPGA that will never work for your application. Do you want to write the logic for the FPGA in VHDL or Verilog (hint - I only use VHDL !!) MK

Lattice XP2 Brevia Dev Kit - How to Connect an parallel ADC?

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