Hi,

I am interested to know if I can use AD9858 to generate a non-linear chirp.

For example, if I only need the update rate of each freq word to be 1 microsec, can I set the frequency and respective phase of each update? What are the potential issues? Will the output turn out to be like a quadratic chirp?

Zhi Hao

Hi Zhi Hao,

Using the maximum DDS clock value of 1GHz would create a SYNCLK frequency of 125MHz. So the update rate of 1 microsec is achievable. You can set the phase and frequency on each update. I advise that you latch those values first then issue FUD so you have a simultaneous change of phase and frequency on each update. So the potential issue is when the phase and frequency are not updated simultaneously. It can be a quadratic chirp if you provide the successive FTW's to be quadratic. The sweep generator that we have is linear so you need to manually input the FTWs to the registers.

Thanks

Louijie