Variable ramp generator

[mbartkow at ET.PUT.Poznan.PL]

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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