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Need help for select a DVGA for DDS function and change duty cycle of wave

Question asked by naserturk on Apr 28, 2012
Latest reply on Apr 30, 2012 by musach

Hello everyone

I’m naserturk from Turkey Istanbul

Firs accept my apology for my bad English


I’m trying to design a DDS Base function generator


I have some experience with AD9833 & AD9834


I need VGA ( Variable Gain Amplifier ) circuit for my DDS function generator output stage




I want to be able controlling output gain value digitally 


Frequency of this DDS is between 10 Hz to 5 MHZ and output impedance 50 ohm


Do I need any buffer in output of DVGA circuit ?


Another question that I have is :


How can I change duty cycle of square wave and saw tooth wave digitally ?


And I know that some of analog device IC’s can help me


Can you help me to find a good IC for this output stage?


Tanks a lot for you helps