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AD9910 DRG mode

Question asked by Giomaca on Feb 24, 2011
Latest reply on Apr 8, 2011 by blw184

Hello,

I'm using the AD9910 DDS to generate a chirp waveform.

To do this I configure the AD9910 in DRG mode in no-dwell high operation.

After that, setting the Digital Ramp Limit register, the Digital Ramp Step Size register and the Digital Ramp Rate register I can choose the characteristic of the waveform (ramp limits, ramp rate, ramp step).

To start the chirp generation I use a positive impulse on the DRCTL pin.

 

Analizing the output of the AD9910 I noticed a strange behaviour.

If I want generate a chirp with a duration of 32 us every 100 us the AD9910 generate two consecutive ramp every DRCTL impulse, while I expected only one ramp every DRCTL impulse.

 

Can someone explain me if I have missed something to do or how I can avoid this behaviour?

 

Thank you for your help!

Regards!

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