Electronic circuits used to create or modify specified time-varying electrical voltage or current waveforms using combinations of active electronic devices, such as transistors or analog or digital integrated circuits, and resistors, capacitors, and inductors. Most wave-shaping circuits are used to generate periodic waveforms. See Integrated circuits, Transistor
The common periodic waveforms include the square wave, the sine and rectified sine waves, the sawtooth and triangular waves, and the periodic arbitrary wave. The arbitrary wave can be made to conform to any shape during the duration of one period. This shape then is followed for each successive cycle.
A number of traditional electronic and electromechanical circuits are used to generate these waveforms. Sine-wave generators and LC, RC, and beat-frequency oscillators are used to generate sine waves; rectifiers, consisting of diode combinations interposed between sine-wave sources and resistive loads, produce rectified sine waves; multivibrators can generate square waves; electronic integrating circuits operating on square waves create triangular waves; and electronic relaxation oscillators can produce sawtooth waves. See Alternating current, Diode, Multivibrator, Operational amplifier, Oscillator, Rectifier
In many applications, generation of these standard waveforms is now implemented using digital circuits. Digital logic or microprocessors generate a sequence of numbers which represent the desired waveform mathematically. These numerical values then are converted to continuous-time waveforms by passing them through a digital-to-analog converter. Digital waveform generation methods have the ability to generate waveforms of arbitrary shape, a capability lacking in the traditional approaches. See Circuit (electronics), Logic circuits