Quadrature VCO Module finished
gstopp at fibermux.com
gstopp at fibermux.com
Fri Sep 8 22:07:04 CEST 1995
My question exactly. Don beat me to it. It looks like you have two
tri-square generators linked together somehow to get a 90 degree phase
difference regardless of frequency. I would presume that they have
identical currents from the exponential converter (BTW what kind of
expo converter are you using?). Perhaps the zero-crossing of one
triangle is used to reverse the direction of the other triangle, like
my tri-square sync idea?
______________________________ Reply Separator _________________________________
Subject: Re: Quadrature VCO Module finished
Author: don at till.com at ccrelayout
Date: 9/8/95 11:39 AM
>Date: Fri, 08 Sep 1995 09:40:00 -0700 (PDT)
>From: Haible_Juergen
>
>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?
>
>-- Don
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