Of course such a wave is possible if one makes a custom waveform as I did:
Alpha-Stim.csv, please check the attachment
Here is what alpha-stim.csv looks like when charted in a spreadsheet:
2. To do this you need also a bidirectional constant current source that can be modulated.
The easiest way to do it (so far) is here:
For more details, please check the link: