What device is used to generate a clock signal in digital circuits?

In digital circuits, an oscillator is the device that generates a clock signal. The clock signal is crucial as it provides timing control for the operations of sequential circuits and other digital components. Oscillators convert direct current (DC) signals into alternating current (AC) signals, producing a periodic waveform that can be square, sine, or triangular. This waveform is used to synchronize the operation of various components within a digital system, ensuring that data is processed and transferred at the correct times.

While other components like resistors, capacitors, and transistors are essential in electrical circuits, they do not directly create clock signals. Resistors are used to limit current flow, capacitors store and release energy, and transistors act as switches or amplifiers. None of these components generate the periodic clock signal necessary for the timing coordination found in digital electronics; that role is specifically fulfilled by oscillators.