SEM VCO buffer

[Haible Juergen]

	>the two inverters/two resistors type is the typical kind of circuit
we
	>find in books only. 

Well, I used it quite often, but sometimes the nonlinear load effect 
on previous stages is a problem.

	>In reality (at least in ICs) something different is
	>used (no good resistors in CMOS logic process).  

Obviously.

	>If you have an old CMOS CD40xx databook I'm sure that you'll find
the
	>schematic there. The feedback is done via currents. This simple
circuit
	>is very dependend on Vdd (no problem) but no much on temperature
(which
	>is good).

I thought I had checked that. But guess what ? I didn't find the schemos at
the 4093, and never went on to the 40106. There it is (;->).
I assume the hysteresis is just set by the "strength" of the first stage
overriding the second one. 

Thanks,

JH.