Hi
I have the following task:
Design a circuit using only one OpAmp witch outputs a triangular waveform with a frequency of 38kHz. The power supply provides me with 20V dc only.
The only circuit i found online was using two OpAmps. One for producing a Square waveform and the second one transformed it to a triangular.
Any help would be appreciated.
Thanks a lot.

 

Welcome to AAC!

Is this homework?

 

Consider this:

 

Welcome to AAC!

Is this homework?

Nope!. It's just part of a much bigger project.

 

Nope!. It's just part of a much bigger project.

There's a reason why they use 2 opamps. The integrator needs something to switch it from charging to discharging. A square wave input does that.

 

In theory you could do it with one op amp square-wave astable oscillator driving two transistor current mirrors that charge and discharge a capacitor.
But that's more complicated then using two opamps.

 

The ICL8038, IIRC, did that precisely.

My feeling is that at 38 Khz it should require little tweaking.

In theory you could do it with one op amp square-wave astable oscillator driving two transistor current mirrors that charge and discharge a capacitor.
But that's more complicated then using two opamps.

 

One possibility -

https://pcbisolation.com/blog/triangle-wave-generator/


Regards, Dana.

 

One possibility -

That generates an exponential triangle-wave, if that is okay with the OP.

 

That generates an exponential triangle-wave, if that is okay with the OP.

If you rig the positive feedback so the triangle is small amplitude this would limit the non-linearity.

 

Nope!. It's just part of a much bigger project.

Where does the restriction that you can only use one opamp come from?

 

TS, original post -

Design a circuit using only one OpAmp witch outputs a triangular waveform with a frequency of 38kHz.

Regards, Dana.

 

My question is where does this restriction come from? Normally it would be a restriction imposed by the homework problem, but the claim is that this isn't homework but rather part of a much bigger project. So why the restriction? Such a seemingly arbitrary constraint in a real project normally has lots of other impacts as well. Is it due to cost? Layout size? Parts availability? Each of those probably splashes over to other parts of the design.