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Using the 9835 to generate 1-25Vpp at 300-800kHz

Question asked by RMLEARNEY on Dec 16, 2010
Latest reply on Jan 31, 2011 by LiamR



I'm intending to create a function generator that can output between 300-800kHz (selected by a PIC) with the output tapped to a different part of the circuit to run through a phase selector (also controlled by the PIC) before feeding into a lock-in amplifier. I'm hoping also to be able to generate Vpp outputs of between 1 to 25Vpp.


This is my first time using DDS chips, and despite some nice circuit diagrams on the net and reading through the datasheet, I've been left with a couple of questions:


1. What is the typical/maximum Vpp output of the 9835


2. What is the resolution of the sine wave generated at approximately 500kHz (i.e. how many steps will my sine wave have)


3. Do you have any recommendations for smoothing my sine wave if it's too 'stepped' - what form of filter would Analog have for this usage?


4. Do you have any recommendations for Programmable Gain ICs produced by Analog that could boost the 9835's output to the range required with as little noise as possible?


Sorry to hit you with these all at once, but I've got help from an EE student in my department for all other parts of the circuit except these.