25Khz Triangular Generator Help Needed

[Frosty_47]

Hello, I am attempting to design a 25Khz triangular generator. I don't want to use any timers or digital IC's for this. I tried the tradional integrator/shmitt triger aproach but my waveform is badly distortted every time. I tried doing this with 3 or 4 different kinds of op-amps and yet I can't get a stable and undistortted output. I can get stable nice output on low frequencies of 1Khz range but I get just pure garbage at the output past like 8Khz. I can't even get a stable waveform in Multisim. Is there something wrong in using the shmitt trigger/integrator for this ?

Thanks

 

[duffy]

Post a schematic, dammit! The Schmitt triggered square wave oscillator and an integrator ought to work. Need to see what you're doing wrong.

 

[Frosty_47]

Ooopps forgot about Slew Rate...

I apologies for causing inconvinience to all with this post. It seems I have neglectted one of the most important parameters of op-amps. Slew rate that is. I calculatted that for 10% distortion and 20Vpp output, I need an op-ap with at least 10V/us slew rate. All Op-amps I used last night for my project did not meet that criteria. It's no wonder I was getting insane distortion at the ouput. I modeled my circuit in multisim today using LF400 (60V/uS) and the output actualy looks much closer to the wave I wantted.

Please accpet my apologies for taking up your time...

 

[duffy]

That's ok, no need to apologise for that one. Slew rate issues cause lots of problems. Glad you found it!