Variable ramp again

[Martin Czech]

:::Now you have independent control of the positive and negative going
:::ramp times. Voltages applied common mode to both current
:::sources change the frequency. Voltages applied differentially
:::to the current sources change the waveshape. It seems that
:::it now becomes a matter of linearity. Correct adjustment
:::of the gain of the inverter used to generate the differential
:::signal, should allow the sum of the two signals to remain
:::very close to 0.

Voltages applied differentially to the current cources do also 
change frequency, as long as no function like 1/x is applied.
This was the main idea: how to change waveform without changing
frequency at all.

AFAIK the waveshaper (ota + min/max) idea is the only one that will
allmost satisfy all needs: fast modulation, stable frequency.
It will be hard to get steep sawtooth slopes.

I'm still puzzled about how the Maxim people do this in the MAX083,
which I now have as measurement generator.

m.c.