Yes, most of the time, it is a 3-angle wave. After the triangle wave, a comparator is added to form a square wave. In fact, the modulation unit itself is composed of a comparator and a logical AND, or the logical AND gate itself has upper and lower limits (similar to the comparator with back difference), so the triangular wave is no problem.

Y (k) = y (k-1)+x (k-n)-x (k-1)-signal filter

Using this filter, we can get the low frequency signals of high frequency carrier: Y output signal and X input signal.

Original filter: h (z) =1-(1-z (-n))/(1-z (-1))

Extended data:

According to the change of the corresponding load, the bias of the base of the transistor or the gate of the MOS tube is modulated to realize the change of the conduction time of the transistor or the MOS tube, thus realizing the change of the output of the switching regulated power supply. This method can keep the output voltage of the power supply unchanged when the working conditions change, and it is a very effective technology to control the analog circuit with the digital signal of the microprocessor.

Pulse width modulation (PWM) is a very effective technology to control analog circuits by using the digital output of microprocessor, which is widely used in many fields from measurement and communication to power control and conversion.

Baidu encyclopedia-pulse width modulation