Oscillators Analog Devices

But after all, what exactly is an oscillator?

Simply put, an oscillator is a component capable of generating a periodic electrical signal, typically a sine wave or square wave, from a direct-current (DC) power source. These signals serve as the “heartbeat” for the entire system, used to establish the operating frequency of circuits, transmit data, process signals, or synchronize the operation of microchips.

In the world of microcontrollers and microprocessors, without a clock signal, nothing works. Some ICs already contain internal oscillators; however, to ensure stability and accuracy, many designs still require external oscillators that meet specific requirements for frequency, noise, power consumption, and size.

Oscillators are not just about picking any frequency that fits

In practice, in many designs, oscillators are taken lightly — picking any type within the required frequency range, as long as it fits the PCB and the budget. But if you need to generate signals for precision timing systems, RF transmission, or audio applications, choosing the wrong oscillator can affect the performance of the entire system.

For example, if you only need a basic signal to run a simple logic circuit, an RC oscillator may suffice. But if you need a stable signal in environments with continuous temperature changes or strong vibrations, a MEMS or quartz oscillator with high precision may be necessary.

What types of oscillators are there?

Oscillators are typically divided into two major groups:

Harmonic oscillators: Generate sine waves and include types such as RC, LC, quartz crystal, ceramic resonator, …

Relaxation oscillators: Use charge–discharge phenomena to generate waveforms, typically producing square waves.

RC and LC: The two fundamental oscillator foundations

RC Oscillator

RC Oscillator uses resistors (R) and capacitors (C) to create phase shift in the signal, combined with an amplifying element to generate a stable oscillation. In many microcontrollers, the RC circuit is built-in and functions as an internal clock source.

Despite its high error rate, the RC oscillator is widely used in applications that do not require stringent accuracy because it can easily generate a signal at low cost and with simple components.

LC Oscillator

LC Oscillator uses a resonant circuit consisting of an inductor (L) and a capacitor (C). When the capacitor is charged and discharged through the inductor, the energy oscillates between the two components to produce a continuous alternating current signal. LC oscillators are often used in RF applications or where high frequencies are required.

However, inductors typically occupy more space and frequency stability is affected by temperature, making this type of oscillator not always ideal if high accuracy is needed.

Choosing the right oscillator for your project

If you are designing a system that requires precise timing—such as measuring devices, RF transceivers, or real-time control systems—don’t overlook carefully selecting the oscillator you use. It’s not just about frequency; you also need to evaluate:

Temperature stability

Electromagnetic interference

Requirements for size, voltage, and power consumption

Product budget

Today, many high-quality oscillators are available on the market at various price points and accuracy levels. There are types such as VCOCXO (Voltage-Controlled Crystal Oscillator) with stability up to ±1 part per billion, and even atomic oscillators with ultra-low drift over long periods—though they come with higher price tags.

Conclusion

Oscillators are a core component in every electronic system with clock signals. Though small, they determine much of a device’s accuracy and overall performance. Therefore, understanding their operation and knowing how to choose the right oscillator is an essential circuit design skill.

If you are looking for RC, LC, or MEMS oscillators, check out the Oscillator catalog at EMIN to select the product that fits your needs.