Variable ramp generator

[harry bissell]

OOH!! I want to play too... I'm simulating this circuit on the computer in
very simple form (perfect components and all).  I notice that the two
sawtooth waves have to have (let's say) their most negative potential at
0VDC.  I'll post something later tonight so y'all can see what I'm doing...
:^) Harry

mbartkow at ET.PUT.Poznan.PL wrote:

> Martin Czech <martin.czech at intermetall.de> wrote:
>
> > I did my homework, and I came of course to the same formula.
> > I guess the best way would be a temperature compensated PWL
> > diode network, I think it has to be in the feedback
> > path, because you need d/dx f < 0. Then the OTAs would
> > just scale the saw waves.
>
> Yeah, that should do. It's funny to observe somebody's favourite
> solutions, BTW :-)
> PWL diode ladder should be sufficiently precise in this application,
> but I personally prefer to use one chip instead of several diodes.
>
> Tietze & Shenk (among many others) show, how to built a dividing
> network by the use of a multiplicator (I think an OTA should do)
> in a feedback of an inverting amplifier:
>
>         --------------
>         |            |
>         -     |\     |
> Uz o-->|X|--->|-\    |
>         -     |  \_--o---o Uy ~ Ux/Uz
>               |  /
> Ux o--------->|+/
>               |/
>
> I am going to check this ASAP.
>
> thanks for all,
>
> mb
>
> --
>
> Maciej Bartkowiak, PhD
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> Institute of Electronics and Telecommunication     fax: (+48 61) 8782572
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>
>