From the JV1010 Reference Manual:
"The Booster is used to distort the incoming signal.
You can also create a PWM (Pulse Width Modulation) like effect by using a Tone's waveform (WG1) as an LFO to shift the other Tone's waveform (WG2) up and down. This parameter works best when you use it in conjunction with the Gain parameter (PATCH/WG/Wave Param)."
What Roland is trying to say?

Mgomes