CrossRoads:
Can run a DAC at whatever frequency you want.
For example, you can easily use this 12-bit DAC and send it data at 500 Hz, low pass filter it at 250Hz, and your 100Hz should be pretty clean if you physically separate the analog and digital signals to help keep digital noise out of the analog.
MCP4921-E/P Microchip Technology | Integrated Circuits (ICs) | DigiKey
Thanks very much. Could you help me to understand how this is superior to a PWM approach? Looking at eg the sparkfun dac which is a breakout of the mcp4725, it appears have to have quite broad spectrum noise. I am (probably unrealistically!) looking to produce a +/-1V sinusoid with only nV noise in the 1-100Hz band. Is this feasible?
And what sort of LPF would you advise for superior results?