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AD9789 application schematic

Question asked by Jaime on Jun 28, 2013
Latest reply on Jun 28, 2013 by danf

We are starting the design of a modulator board using AD9789 as output DAC at RF frequencies (up to 900MHz).


We use to split the power supplies and the ground planes into analog and digital part, even if this leads to increase the number of layers.


But as in other ADI DAC boards the AD9789 EVB splits the power supply but keep a single ground plane both for digital and analog.


In our board one has to consider not only the DAC but many other complex chips including a large FPGA, several transceivers and a master clock at 2.4GHz.


Does ADI recommend to keep a single GND plane for the DAC, or for any complete circuit that uses the DAC?


We respect the careful decoupling schematic with wideband capacitors, and this has a connection with the way the GND s routed; but normally we would split the GND into analog and digital which would affect the DAC. If the recomendation for AD9789 is keep a single GND plane we would be forced to split anyway the ground for the low frequency part and take a single frontend GND that would be tied to the analog GND of the rest of the circuit, keeping the DGND plane only for the "low frequency" DGND not including the DAC DGND if ADI does not recommend it.


Thanks in advance


Jaime Martin