Sawtooth Signal Generator: How does it work?

A Sawtooth Oscillator and sawtooth waveform generator circuit is shown and analyzed in this tutorial video. See the circuit playlist for more circuit examples ( • Analog Computer with O... . The circuit operation is first discussed and then the period and frequency of the generated sawtooth voltage is computed as a function of resistors and capacitor in the circuit. This circuit is implemented with two operational amplifiers and two diodes. One op amp in this circuit has negative feedback configuration and hence benefits from the virtual short property. The other op amp has positive feedback configuration and works like a comparator or more like a Schmitt trigger. A combination of KCL, KVL and linear charging of capacitor is applied to explain how this circuit is operating and to find the formula for the period of the sawtooth waveform.

[@STEMprof]

Thanks for watching. For more Analog Circuits, Oscillators Op Amps and Transistor examples see Triangle Oscillator Op Amp circuit ua-cam.com/video/JF5Up_cuL9k/v-deo.html
Complex Sinusoid Oscillator ua-cam.com/video/GXRhmwmS5Zk/v-deo.html
Sawtooth Oscillator Design ua-cam.com/video/2eUsGPfqbW4/v-deo.html
Full-Wave Rectifier circuit example ua-cam.com/video/DJJMNU-CYcg/v-deo.html
Sawtooth Waveform Generator design with OpAmp, JFET, BJT: How does this circuit work? ua-cam.com/video/5zHXTx-Vl20/v-deo.html
Diode-Amplifier VTC is analyzed in ua-cam.com/video/vpGZkafxMJM/v-deo.html
For more circuit examples please check the circuit videos playlist: ua-cam.com/play/PLrwXF7N522y4c7c-8KBjrwd7IyaZfWxyt.html
I hope these analog circuit examples and videos are interesting and helpful. 🙏

[@WaveIO]

I LOVE these videos. Thank you for your time and experience to make them!

[@STEMprof]

You're welcome. Thank you for watching and comment. Glad that you like this Sawtooth Oscillator video. Pls see more examples: Triangle Waveform Generator ua-cam.com/video/JF5Up_cuL9k/v-deo.html
Complex Sinusoid Oscillator ua-cam.com/video/GXRhmwmS5Zk/v-deo.html
Sawtooth Waveform Generator design with OpAmp, JFET, BJT ua-cam.com/video/5zHXTx-Vl20/v-deo.html
Full-Wave Rectifier circuit example ua-cam.com/video/DJJMNU-CYcg/v-deo.html
Diode-Amplifier VTC is analyzed in ua-cam.com/video/vpGZkafxMJM/v-deo.html
For more circuit examples please check the circuit videos playlist: ua-cam.com/play/PLrwXF7N522y4c7c-8KBjrwd7IyaZfWxyt.html
I hope you like these Analog Circuits as well. 🙂

[@saarike]

Absolutely great!!! My humble thanks for great vid.

[@STEMprof]

Thank you for watching and comment. Glad that this oscillator circuit analysis video is helpful. For more circuit examples please check the circuit videos playlist: ua-cam.com/play/PLrwXF7N522y4c7c-8KBjrwd7IyaZfWxyt.html

[@STEMprof]

Thanks again for watching and your interest. I have posted a few more circuit examples: Triangle Waveform Generator circuit ua-cam.com/video/JF5Up_cuL9k/v-deo.html
Complex Sinusoid Oscillator ua-cam.com/video/GXRhmwmS5Zk/v-deo.html
Sawtooth Waveform Generator design with OpAmp, JFET, BJT: How does this circuit work? ua-cam.com/video/5zHXTx-Vl20/v-deo.html
Full-Wave Rectifier circuit example ua-cam.com/video/DJJMNU-CYcg/v-deo.html
Sawtooth Oscillator OpAmp Circuit ua-cam.com/video/2eUsGPfqbW4/v-deo.html
Diode-Amplifier VTC is analyzed in ua-cam.com/video/vpGZkafxMJM/v-deo.html
For more circuit examples please check the circuit videos playlist: ua-cam.com/play/PLrwXF7N522y4c7c-8KBjrwd7IyaZfWxyt.html
I hope you like these circuits as well. 🙏

[@dnkreative]

Very nice. Can this be done with unipolar power supply? And how to make the frequency controlled by voltage?

[@STEMprof]

Thanks Dmitri for watching and your good question. Glad that you liked this video. Yes, it is possible to implement this Sawtooth Oscillator using unipolar power supply. It just requires proper DC biasing of the input terminals of the two operational amplifiers in this circuit. For another oscillator example with Op Amp, JFET and BJT transistors please see ua-cam.com/video/5zHXTx-Vl20/v-deo.html

[@dariushsafari]

Where did suddenly number 2 come from in T=2(R2+R1)C ? Even though it is correct in this case (R3=R4), it needs more explanation. If R3=2R4, then T=(R2+R1)C, which looks more familiar in RC circuits.

[@STEMprof]

Thanks Dariush for watching and your follow-up comment. The factor 2 appears because output voltage has to traverse from -Vdd=-5 to +Vdd=+5 (meaning 2Vdd total) while driving voltage force charging or discharging the capacitor is either Vdd or -Vdd. I hope this further explanation is helpful. 🙏

[@fouadnano]

Nothing changed c
I removed it and nothing changed
Why did you put it?

[@STEMprof]

Capacitor is required for linear integration of voltage in order to generate linear increase in Sawtooth Waveform. Op Amp itself has some internal capacitor as well between its output and inputs. But value of that cap is usually very small depending on specific Op Amp.