Variable ramp generator

[Martin Czech]

:::I think the best way to achieve a constant amplitude is to scale the both
:::saws in such a way, that the "meeting" point is allways at the same height.
:::A simple calculations (for simplicity let's assume the cycle length is 1
:::and the meeting point is at 1) reveal, that if the rising saw is scaled by
:::a (a is the symmetry factor, in the range 1...+inf), the falling one should
:::be scaled by a/(a-1). Now, it would be great to have the symmetry voltage
:::controlled. Is there a simple way to realise the f(x)=x/(x-1) relation ?
:::I think an OTA-based one-quadrant voltage division circuit is reasonable,
:::but maybe there is a simpler way ?
:::

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.

m.c.