A sawtooth waveform is a type of linear non-sinusoidal waveform with a triangular shape in which rise time and fall time are different. Sawtooth wave generators produce a sawtooth waveform, typically used in applications such as thyristor switching, sampling, timebase generators for oscilloscopes and television systems, modulation, etc.

Sawtooth Wave Generator Circuit

Sawtooth waveform may be generated by using an asymmetrical astable multivibrator followed by an integrator as shown in the figure above. The difference between a triangular waveform and a sawtooth waveform is in the duration of the rise time and fall time. A triangular waveform has equal rise time and fall time whereas a sawtooth waveform has unequal rise time and fall time. A triangular waveform generated can be converted to a saw tooth wave generator by including a variable DC voltage into the non-inverting terminal of the integrator.

The circuit uses a potentiometer. The output of the integrator is a triangular wave that depends on a DC level that is a function of R₄. The polarity and amplitude of the DC level determine the duty cycle of the square wave. A duty cycle of less than 50% will result in the output of the integrator being a sawtooth waveform. When the wiper is at the center of R_4, the output of the integrator is a square wave. As it moves towards -15 V, the rise time of the sawtooth waveform becomes longer than the fall time. And when the wiper moves towards +15 V, the fall time becomes longer than the rise time.

Sawtooth Generator Waveform