I am having some small issues understanding the waveform conversions. How is the phase accumulator value used to generate the respective waveforms? I am working with both the AD9833 and AD9838.

For triangle waveform, how does the phase accumulator value leads both ramp up and down at the DAC and is the period 2*pi?

The datasheet for the AD9838 (p. 21, fig. 23) and 9833 (p. 16, fig. 25) are different.

http://www.analog.com/media/en/technical-documentation/data-sheets/AD9838.pdf

http://www.analog.com/media/en/technical-documentation/data-sheets/AD9833.pdf

For the sin waveform, I understand there is a 12-bit sin LUT, is only a quarter of the waveform stored? Is the first and last value 2^12/2 or 2^12/2 - 1? This influences the square waveform also, since the MSB is used at the SBO?

Thanks.

Hi,

As you correctly mentioned, there is an error in the AD9838 triangle figure. I'll edit ASAP.

The triangle only takes the value directly from teh accumulator and load into the DAC, without the LUT conversion.

The LUT only store quarter waveform as the sine wave is symmetrical, but I'm not fully understand the question related to the data stored into the LUT. Could you provide more details, please?

Probably most of your question are answered here,

A Technical Tutorial on Digital Signal Synthesis, 1999 | Education | Analog Devices

Regards,

Miguel