I am new to DDS. I have a AD9954 EV. Ref Clock (fs) of 200MHz is used to obatin fo=40MHz.
The EV software calculated that : TWV=0858993459
fo=0858993459*200e6/2^32 ~ 40MHz
However I don't see the any output at all? Anyone know why?
Can you look at the board to see how the output is connected? The AD9954 eval schematics on our website should help. If looking at the DUT1 schematic, there are a set of zero-ohm resistors (R4, R5, R6, and R7) that can be inserted or removed plus there is jumper W1 for connecting the un-filtered Iout (seen at J2) to the reconstruction filter whose output is J1.
I can get a output. For example, i can get a 41MHz output (TWV=0880468296). However I can't see any signal at all when I set it to 40MHz.
On my board:
W1 set to 1-4, (Bypass filter) and i am getting output at J2.
Just to add with regard to the zero ohm resistors (R4, R5, R6 and R7), the #4 note specifies the usage of these resistors.
I am using R6 and R7 and take the output after the transformer. Is it a problem?
No, that won't be a problem at all.
Message was edited by: Andy Rose - Fixed username.
What is the amplitude of the output signal when set for 41MHz? Does it decrease the closer you get to 40MHz? The AD9954 should be capable of outputting 40MHz.
I am writing the stp file manually and load the values to AD9954 with the EV software now. It works ok this way.
Can you verify the EV software 1.0.1 is actually working okey.
I don't have an evaluation board to test with, but v1.0.1 looks to be newest revision that's currently on our website.
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