Fab Filter One

FabFilter One is a synthesizer plug-in with an oscillator, but with perfectly fine-tuned controls and the best possible sound and filter quality.

One: In a fit of excessive creativity, Frederik and Floris have called their first product "One". One is an analog synth with super-fat self-oscillating filter, an equally super-fat oscillator with the classic waveforms: sawtooth, triangular (sine) and square waveforms, the latter with variable pulse width.

Oscillator and filter can be modulated with an LFO with triangular and square waveforms, where you can adjust the balance between the two and then with an Envelope Generator with traditional ADSR.
In other words, a concept you have heard of a few times before, but very well executed. Listen to a demo here: http://www.fabfilter.com/products/ffone-demo.mp3