It is known that AD9833 Programmable Waveform Generator can generate Sinusoidal/Triangular/Square Wave Outputs. However, in our application, we need Quasitrapezoidal waveform. Is it possible to generate this waveform by programming AD9833?
The answer is no, sorry, unless you include to external diodes to clamp your output signal at the level you want... probably this solution is not optimum and complex due to the output voltage tolerances in this device.
Said that, there are other DDS that includes internal RAM, which can be used to generate your desired output signal.
Thank you so much for your reply. Can you suggest any specific DDS that includes internal RAM?
AD9954 and AD9910 both have onboard memory. If you want to use that to establish a trapezoidal waveform shape, you should be able to do so; we haven't used it for that specific purpose though. Another option might be to use a device with amplitude sweeping capability, setting your FTW (frequency tuning word) to 0 and your POW (phase offset word) to 90 degrees, which would just pump out max value from the DDS engine each cycle, then use the sweep function to sweep the output scalar between 0 and 1.
Thank you so much for your suggestion.