I don't know if the synthesis method is patented, but I really. want. this. OSC. in. Voltage: https://www.youtube.com/watch?v=ufBeolCjWSw
Basically, geometric shapes throw the X axis out one output (left) and the Y axis out of another (right), as the XY coordinate moves clockwise at audio rates. FM is included.
To be honest, I'm wondering if there are other ways of accomplishing similar output, such as with Haas delay and phase modulation; but I'm just speculating at this point.