Crystal oscillators can help electronic systems provide frequencies for synchronous operation, as frequency references or to achieve accurate timing.

In microprocessor-based systems, there are several different frequency signals used to execute instructions, move data into and out of memory, and external communication interfaces.

A simple embedded controller may have a clock frequency of several MHz, while microprocessors in personal computers usually expect an input frequency of 15 MHz. This will multiply internally to provide the frequency of the CPU and other subsystems. Other components in the system may have their own frequency requirements.

In addition to providing the basic requirements of the specified frequency, the oscillator may have to meet other requirements depending on the application requirements of the product.

For example, many product applications require extremely precisely defined frequencies. This is particularly important for systems that need to communicate with other devices through serial or wireless interfaces. Accuracy is usually measured in parts per million (PPM).

At the same time, the trimming circuit can be based on resistance capacitance (RC) or inductance capacitance (LC) networks. These devices are relatively simple and can change the frequency in a wide range. However, designing an accurate RC oscillator or LC oscillator requires the use of expensive precise components. Even so, they cannot meet the highest accuracy and stability required by many product applications.

Crystal oscillators (usually quartz) can also be used as resonant components. Cut the crystal into two parallel crystal planes and deposit metal contacts on them. Quartz has piezoelectric effect, which means that when the crystal is placed under pressure, voltage will be generated on its crystal surface. On the contrary, when voltage is applied to the crystal, the crystal will also change its shape.