I have made a 0-1V Signal in square/triangle to saw converter. I used a LZX VCO (video oscillator). On high frequencies I get this spike you can see on the oscilloscope image. Is there a way I can remove this spike? It comes from the squarewave going into the 2N3819 FET transistor. Maybe there is a better transistor that can handle the high frequencies? Just a thought....

 

It is in the design of your circuit and shouldn't be there.
We can't see the full circuit diagram in order to see how your circuit works.

 

It is in the design of your circuit and shouldn't be there.
We can't see the full circuit diagram in order to see how your circuit works.

 

View attachment 215136

The IC is a LM6172

 

You are still not showing us the complete circuit .
And what is the opamp supply voltage?

 

You are still not showing us the complete circuit .
And what is the opamp supply voltage?

+/- 12v

 

+/- 12v

This is the oscillator circuit
https://raw.githubusercontent.com/l... Voltage Controlled Oscillator Schematics.pdf

 

I can calulate JFET DC bias for the most part, this weekend I better learn their small signal AC model, which I can probably guess what it is, and give this a go. They are fun, wish I learned them earlier, and MOSFETs.