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AD9910 Sweep frequency source in DRG mode

Question asked by Zze on Jun 8, 2017
Latest reply on Jun 22, 2017 by KennyG

Hello,I have some questions about AD9910 to consult.I want to use AD9910 to generate a circular sweep signal source .

The limit of sweep frequency:1MHZ—21MHZ

Step size:100HZ

Rate size:50ns

According to parameters set above,the total sweep time from 1MHZ to 21MHZ is 10ms,the Fsysclk is 800MHZ,belong are some parameters I wrote to the registers.

CFR1:0x00804200

CFR2:0x004e0820

CFR3:0x140f4128

DRLIMIT: 0x06b851ec0051eb85

DRSTEP:0x0000021900000219

DRRAMP:0x000a000a

 

(1)I find the step size of output is 50HZ ,and I messured the output of DROVER pin(in picture 1 belong).the period of DROVER output is 10ms.does the shape of the pulse look a little abnormal?

(2)Accroding to DROVER pin,the total sweep time of output is 10ms.so does it mean the actual rate size is 25ns? why is it different from what I set?

(3)what is more,when I double the value of step size in register,then the step size of output become 100HZ but the total sweep time of output become 5ms.I was confused.I want to know that how I can do to keep the step size 100HZ while the total sweep time is 10ms.

I hope i have express my problems clerly,and I'll appreciate it if my problems can be solved.

Thank you.

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