Hi...for a simple staircase waveform generator, I used half of a four-bit binary counter IC (HC393?) to get up to sixteen steps, with a passive resistor ladder on the outputs (but into an opamp buffer amplifier) to do the digital-to-analog conversion. I put that through a step attenuator and then a small power amplifier. A chipamp (e.g. LM1875, LM3875 or larger) might work well for the power amplifier, although I used an opamp with a BC139/BC140 push-pull booster amp inside the feedback loop, since I didn't need too much power. I configured the small power amplifier as a Howland-type voltage-controlled current source, but could switch in a power-resistor load to make it into a voltage source. That way I could get either calibrated current steps or calibrated voltage steps. I also had an inverting opamp amplifier that could be switched in, before the power amp. That way I could get either polarity for the staircase.