
Title link takes you there.
Some snips:
"To have a quadrature waveform, you really need at least two waves. The first wave could be said to be at 0 degrees, and the second wave could be said to be in quadrature with that wave - in other words, the quadrature waveform is 90 degrees out of phase to the zero degree waveform. The frequency of both waves is the same - it's the offset in phase between the two waves that defines the function.
Figure 1 [top two] illustrates this offset - notice how the lower triangle waveform crosses the center line 90 degrees "behind" the upper triangle wave.
It's easy enough to get two waves at the same frequency and one hundred eighty degrees out of phase - that only requires simple inversion - the 180 degree waveform is merely the exact opposite of the 0 degree waveform. But, to get an offset of 90 degrees, well, that takes some doing....
Applications for the VCQFGThomas' mention of the use of the VCQFG with his SuperSeque design above is just one of a plethora of applications. Consider that, with this module, you have access to four triangle waveforms that are at the same frequency, but have rise and fall segments offset symetrically over time."