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AD9914  linearly sweep  not working

Question asked by puppy on May 18, 2017
Latest reply on Dec 4, 2017 by waderose

Hello,I hope to use a AD9914 for linearly sweep, clk-in is 100MHz,N is12,so the system clock is 2.4GHz.

Then, I connect DRHOLD and DRCTL to GND..  

The sweep frequency generated is 90MHz -- 100MHz,  and the frequency step is 5KHz, Step intervals is 0.1us,

I hope to use No-Dwell high and No-Dwell low configuration, so  it can sweep all the time automatic .

Here is my register configuration:

CFR1=0x0101D000

CFR2=0x000E2100

CFR3=0x00040C1C

CFR4=0x01052120

Digital Ramp Lower Limit=0x09999999(register address is 0x04,90MHz)

Digital Ramp Upper Limit=0x0AAAAAAA(register address is 0x05,100MHz)

Rising Digital Ramp stope=0x000006FD(register address is 0x06,1KHz)

Falling Digital Ramp stope=0x000006FD(register address is 0x07,1MHz)

Digital Ramp Rate Register=0x000A000A(register address is 0x08,0.1us)

 

But finally, It just a constant 90MHz output, then I measured the pin 65 ( DROVER) , it is low ..

So  what happend to my AD9914, I just hope to use it to  realize  linearly sweep or Where did I go wrong for my  configuration or connection.. thank you !

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