Quadrature VCO Module finished
don at till.com
Fri Sep 8 20:22:10 CEST 1995
Date: Fri, 08 Sep 1995 09:40:00 -0700 (PDT)
For all those who are interested, I got my Quadrature VCO
Module finished last night.
It contains a sin / cos VCO, that is built around 2 LM13600's and
some TL07x opamps. The core is a schmitt-trigger / integrator
triangle generator. A second comparator / ota-integrator pair
generates a second triangle wave with 90 degrees phase shift
(as described in Tietze/Schenk, Halbleiterschaltungstechnik).
How does this quadrature part of the circuit work? Is the OTA
functioning as a second integrator? If so, how do you avoid dc offset
drift? Or is the OTA functioning to invert the main triangle every
other quadrant and add the schmitt square wave as an offset? If so,
is there any deglitching? Or is it something else entirely?
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