FPGA Dual DAC Board for QAM Synthesis

Building on the simplicity and success of my DAC board paired with my FPGA dev boards, today I threw together a board with an Altera Cyclone II, two DAC9000Es, an FT245R, and supporting periphery. I'll need to check it with fresh eyes tomorrow to ensure I haven't made any mistakes, but with luck I can submit the design tomorrow evening and have the boards next week.

My DAC+FPGA pair has proved extremely useful for transmitting test signals of various sorts, taking I+Q via USB and generating the output signal in code. But, at 160 MS/s, its max frequency is quite limited. This new board has two of the same DACs, however each will simply generate the I or Q signal alone which will then be combined with an LO in a dedicated QAM modulator chip. This allows for carrier frequencies limited only by the abilities of the QAM modulator chosen, and at 160 MS/s the usable Tx bandwidth will be huge.



I've chosen to terminate the DACs in SMA connectors and leave the modulator off the board entirely, as I'd like to evaluate a few different chips. Unfortunately this board will be too large for me to mill at home at the moment, but I can still quickly mill test boards for QAM modulators in about an hour.