Advice on this triangle wave circuit

May I know why the triangle wave generated by this circuit result a wave-like waveform just like the image attached please?

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How do I fix it just like the Attachment 113214 show please ( it's come from function generator at 20khz )


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Looks like your scope is under-sampling. Try to increase the sweep speed.

Heelo E-design,

Thanks for reply , this is the waveform after increasing the sweep speed ,

pk-pk amplitude is not constant


Which I need is like this (signal come from function generator)

this is the waveform after increasing the sweep speed ,

pk-pk amplitude is not constant

Click to expand...

Do you think that switching the sweep speed changes the output voltage of your generator?

You don't understand how your oscilloscope displays waveforms. In fact it's still undersampling (or a poorly implemented display software) that misses the actual triangle peek.

Why don't you view both waveforms with same number of cycles?

FvM said:

Why don't you view both waveforms with same number of cycles?

Click to expand...

Hello FvM,

here are both waveform on couple sweep speeds ,

upper waveform is generated from circuit,

lower waveform is generated from signal generator.

Looks like something else at around 1KHz is influencing the waveform. Your schematic doesn't show the supply pins, do you have a stable ower supply and decoupling capacitors across the pins, as close to the IC as possible?

Brian.

betwixt said:

Looks like something else at around 1KHz is influencing the waveform. Your schematic doesn't show the supply pins, do you have a stable ower supply and decoupling capacitors across the pins, as close to the IC as possible?

Brian.

Click to expand...

Thanks for reply Brian,

Power supply is stable , tried adding decoupling capacitors across the IC's Vcc and GND still with no luck

Use an analog oscilloscope to avoid the problems produced by your digital 'scope.

Looks like something else at around 1KHz is influencing the waveform. Your schematic doesn't show the supply pins, do you have a stable ower supply and decoupling capacitors across the pins, as close to the IC as possible?

Click to expand...

I don't think so. Both waveforms are displayed pretty similar with reasonable fast time scale (upper two pictures). The difference with slow time scale ist most likely a simple undersampling respectively aliasing effect. The different display of both signals can be caused by slightly different frequency, with the ocilloscope sampling frequency being an integer multiple of the signal generator frequency, cancelling the beat effect.

Use an analog oscilloscope to avoid the problems produced by your digital 'scope.

Click to expand...

That's the point. Or using a digital oscilloscope with more sophisticated signal processing.

If you don't have a access to a better oscilloscope, distrust all pictures that don't resolve a waveform with sufficient number of sampling points.

FvM said:

The difference with slow time scale ist most likely a simple undersampling respectively aliasing effect. The different display of both signals can be caused by slightly different frequency, with the ocilloscope sampling frequency being an integer multiple of the signal generator frequency, cancelling the beat effect.
If you don't have a access to a better oscilloscope, distrust all pictures that don't resolve a waveform with sufficient number of sampling points.

Click to expand...

Got your point FvM , will find a better oscilloscope, thank you.