In electronics and electrical engineering, a ramp generator is a circuit that creates a linear rising or falling output with respect to time.
the ramp generator starts increasing its voltage but, still lower than input X terminal of the comparator the output shall be 1, As soon as the ramp voltage is equal to or more than X, comparator output goes low.
Voltage and current linear ramp generator find wide application in instrumentation and communication systems.
[1] Some ramp generators present also the possibility to change the start-up and return flow time.
[1] Originally, ramp generators were implemented as analog hardware devices.