A pulse generator is either an electronic circuit or a piece of electronic test equipment

Electronic test equipment

Electronic test equipment is used to create signals and capture responses from electronic Devices Under Test . In this way, the proper operation of the DUT can be proven or faults in the device can be traced and repaired...

 used to generate rectangular pulse

Pulse (signal processing)

In signal processing, the term pulse has the following meanings:#A rapid, transient change in the amplitude of a signal from a baseline value to a higher or lower value, followed by a rapid return to the baseline value....

s. This article describes the test equipment.
Simple bench pulse generators usually allow control of the pulse repetition rate (frequency

Frequency

Frequency is the number of occurrences of a repeating event per unit time. It is also referred to as temporal frequency.The period is the duration of one cycle in a repeating event, so the period is the reciprocal of the frequency...

), pulse width, delay with respect to an internal or external trigger and the high- and low-voltage levels of the pulses. More-sophisticated pulse generators may allow control over the rise time

Rise time

In electronics, when describing a voltage or current step function, rise time refers to the time required for a signal to change from a specified low value to a specified high value...

 and fall time

Fall time

In electronics, fall time \scriptstyle t_f\, is the time required for the amplitude of a pulse to decrease from a specified value to another specified value...

 of the pulses.