I am building a frequency generator circuit and need some advice. I am using the AD9833 DDS generator (programmed from a PIC16F876) to generate frequencies and I wish to be able to adjust the gain.
Being unable to find a suitable Programmable Gain Amplifier I was going to use a non-inverting amplifier and a digital potentiometer. The advice I need is:
Is it better (less noisy) to pass the signal through the potential divider (in a passive fashion) inputting in to a unity gain amplifier;
Should I use a digital resistor in the feedback loop of the amplifier and set the gain that way?
Also, if anyone else has any better ideas they would also be welcome, but board space is limited so complex solutions maybe hard to implement.