[timewizard]

> Anytime the duty cycle is not 0%, 50%, or 100%, you will have non-zero even harmonics.

The article is specifically trying to achieve those harmonics. This is the initial problem.

> A linear combination (scaled sum or difference) of two balanced square waves will necessarily still have all even harmonics at zero

Yea, that's why you need the phase offset, as I mentioned.

> and thus cannot emulate a square wave with a duty cycle different from 50%.

You can /synthesize/ a square wave at any duty cycle you like. We're still doing Fourier just without the whole transform.