I'm making a precise, low-current current source for a bio-impedance meter using a howland current pump.
Currently the current pump is driven by a wien-bridge oscillator to produce a 1V p-p 100hz sine wave, my goal is to make it programmable by swapping this for a DDS (AD9852 tentatively). Most commercial DDS ic's are designed for telecom and other high frequency applications and have performance specs available on the MHz level, however information on performance in the low frequency domain is sparse.
SO my question is, how well do commercial DDS IC's perform at frequencies on the order of 100Hz – 1Khz? I'll be sticking an atmega or similiar MCU and will probably drive both the MCU and DDS with a 10MHz clock
Best Answer
100 Hz to 1 KHz really sounds like audio frequencies. I can, and have, used audio DAC's and some opamps to generate arbitrary frequency sine waves in the 20 Hz to 20 KHz range with better than -100 dB THD+N, better than 100 dB Signal to Noise, and very good frequency accuracy (limited by the crystal/oscillator that you use).
Good quality audio DAC's run just a couple of dollars. The highest quality DAC's are maybe US$3 in 1K qty. So it is not that expensive. You'll have to add some opamps to it, but those are cheap too.
You would be hard pressed to do this another way for cheaper and/or with better quality of sine wave.
You can drive the DAC from many MCU's. I did it with an FPGA, but that's because I had an FPGA handy.
I should also point out that @Anindo's comment about getting a cheap module to play around with is completely valid. That module he linked to has the ADI AD9850 on it and it might also do what you want.