The CGS31 is a very standard pseudo-random digital noise source with a few enhancements. Instead of running a fixed high frequency clock, a VCO is used instead, allowing for unusual sweeps, and for reducing the speed right down to a series of random pulses. The internal linear VCO can also be bypassed so an external source such as a 1V/Oct VC or LFO can be substitued. It has pink and white noise outputs, and two separate (unique) digital outputs for use in triggering other circuits.
CGS31 Datasheet and Build Guide