design / development question FPGA (Xilinx), DDS and RF output

[samudra.haque at gmail.com]

Thanks Terry,

 

I am using Vivado/Vitis/HLS 2020.2 and getting ok with the toolchain. On my
SEEED Studio Spartan Edge Accelerator, the board designer has included TI
DAC7311 which is a single-input 12-bit DAC at 3V3 output levels. Can I add
the schematics to tacos BB mailing list - is that permitted?

 

The board is obviously pre-wired, and made in qty, and cheap ! so I would
like to use it. From what I can infer from the data sheet of the device,
this is my guess:

 

DDS IP from XLINX (Spartan-7 FPGA)

Parallel to serial conversion using (?? SERDES ??) IP from XLINX (Spartan-7
FPGA) to external pins

Connection to TI DAC7311

Conversion to Analog output.

 

The DAC is rated up to 50 MHz .. but that refers to the bits/second of the
data transmission, right? For actual RF modulation, that bitstream
(waveform) would have to be mixed to the carrier frequency I am roughly sure
(asking for confirmation). At that stage, could we then transport a 9.6kbps
data stream on say a 144-145 MHz carrier? 

 

Samudra N3RDX

 

From: Terry Fox <tfox at knology.net> 
Sent: Sunday, February 21, 2021 11:02 PM
To: samudra.haque at gmail.com; tacos at amrad.org
Subject: Re: design / development question FPGA (Xilinx), DDS and RF output

 

I did exactly that a number of years ago, using a Digilent Nexys2 in
Verilog.  I made a rough signal generator, and a DUC to match the Charleston
SDR.  I wrote at least the DUC in an AMRAD newsletter article, probably
around 2010 or so.  IIRC, the D/A chip was the famous AD9744, which almost
everyone used.  200MHz clock rate and 12 bit DAC.

Terry, N4TLF

On 2/20/2021 7:15 PM, samudra.haque at gmail.com
<mailto:samudra.haque at gmail.com>  wrote:

I'm trying to expand my skillset (self-education) by writing a FPGA code
block that uses a DDS core IP to produce waveforms. I'm interested In
producing up to VHF (2m band) CW and BPSK waveforms if I can. 

 

I have access to Zynq7010 and Spartan7 development boards - Any
recommendations for a DAC chip that I can use in tandem with this FGPA
device?

 

I'll custom wire a interface for this project. 





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