[sdiy] VC phase shift in Tillman's quadrature trapezoid VCO

[Guy McCusker]

Dear list,

There is one obvious list member who may be best to answer this but it
doesn't hurt to spread the net a little more widely I hope...

Don Tillman's fascinating articles on his Quadrature Trapezoid VCO

http://till.com/articles/QuadTrapVCO/index.html

include the tantalising sentences ""The quadrature trapezoid core also
enables the implementation of voltage controlled phase shift over a
multiple cycle range. I'll cover the details of this in a later
article." As far as I can tell this later article did not appear.

I have tried to figure out how VC phase shift might be implemented but
so far I am not smart enough.

Can anyone point me in the right direction please?

All the best,
Guy.