Understanding Crystal Oscillators | An Ultimate Guide

This ultimate guide will look at frequently asked questions about crystal oscillators. For example, what are the advantages of using crystal oscillators over other piezoelectric materials? If you have been asking this question for a while, you are right where you need to be. 

In addition, this guide will also discuss the types and applications of this electronic oscillator. Finally, you will learn where to find crystal oscillator distributors and the critical factors in selecting the best oscillator circuit.

What Is a Crystal Oscillator?

Crystal oscillators are devices that use crystals as a frequency-selective element to obtain an inverse piezoelectric effect. It uses a piezoelectric resonator as its frequency-determining element – this crystal resonator is a separate component from the crystal circuit. To sustain the oscillation, the crystal oscillator circuit takes a voltage signal from the resonator, amplifies it, and returns feedback.

Are you familiar with the technology used to design watches, digital integrated circuits, and radio transmitters? These are examples of electronic systems that require crystal oscillators and those that need a ‘frequency-determining element’ and time tracking.

3 Types of Crystal Oscillators & Their Applications

Crystal oscillators are applied in almost all electronic devices and industrial applications. This is why there is a wide variety of crystal oscillator types. Sometimes, it is challenging to keep up with which kind goes where but you are in luck, for we will be looking at the three main types of crystal oscillators and their applications.

1. VCXO Oscillators

VCXO oscillators, known as Voltage-Controlled Crystal Oscillators, are electronic circuits with a frequency that an externally applied voltage can adjust. Varactor diodes are responsible for maintaining this oscillator type.

It is important to note that VCXOs have different applications in frequency modulation (FM) and phase-locked-loop (PLL) systems. In simple terms, this type controls the change in crystal output by using DC voltage.

Application Examples

• Base station
• PC
• FPGA
• DSP
• Smart grid
• SATA
• SAS

38 Series SMD 3225 VCXO

2. OCXO Oscillators

Oven Controlled Crystal oscillators or OCXO are electric types controlled by temperature from a mini-internal oven. This oscillator achieves the best frequency stability possible in a crystal and performs best with applications that require temperature stabilities of ±1 x 10-8.

An OCXO uses components in satellites and telecom devices and is considered the most stable oscillator type. However, due to their large size and power requirements, it is not used in small, battery-charged devices.

Application Examples

• Base station
• Digital switch
• Reference Timing Circuit
• Measuring equipment
• Synthesizer

9X Series SMD OCXO

3. TCXO Oscillators

Similar to OCXOs, TCXOs, Temperature Controlled Crystal Oscillators manage the temperature of the oscillator circuit. However, unlike a typical OCXO, TCXOs have VCXOs as their basic building blocks with approximately a ±50 ppm deviation range. This type uses a temperature-sensitive network and is designed to withstand significant variations in ambient temperature.

Application Examples

• Mobile Phone
• Wearable Electronics
• IoT
• GPS
• WLAN

7X Series SMD 2016 TCXO

Working Principles of Crystal Oscillators

Crystal oscillators are made from quartz and usually rely on their ability to change shape under an electric field. In simpler terms, crystal oscillator circuits operate under the principles of reverse piezoelectricity.

When the electric field is removed, the quartz generates another electric field as it returns to its former shape, which can produce a voltage. The resultant effect shows the quartz crystal behaving like an RLC circuit with a precise resonant frequency and components of an inductor, capacitor, and resistor.

5 Reasons You Should Use Crystal Oscillators

Let’s answer this general question, ‘what are the advantages of crystal oscillators?’ Of course, thanks to these oscillators, no one can deny quartz watches’ superior power and mechanics. However, that is not the only advantage you are looking for in this device.

Here are five reasons you should use crystal oscillator circuits in your next application.

1. Crystal oscillators are stable and can generate frequencies under any condition. This frequency stability is attributed to the mechanical strength of certain crystals, like the quartz itself.
2. Oscillators have high Q-factors and longer life. This lower energy requirement contributes to the constant and stable frequency produced by this electronic component.
3. Quartz crystals can be cut to precise dimensions. This means you can customize the vibration frequency based on your application requirements.
4. The low phase noise of this electric component increases its signal quality. This is possible by the one-axis vibration of crystal oscillators.
5. Crystal oscillators are compact and inexpensive. This is mainly why they are prevalent in various industrial applications.

The truth is, there are more than five reasons to use a piezoelectric device in your next project. The following section looks at crucial specifications and criteria in selecting a crystal oscillator.

What To Look for When Selecting a Crystal Oscillator

If you want to use an oscillator in your new application, you should check some specifications and critical criteria. We highlight a few points below to make your selection process easy.

• Operating Frequency & Stability: based on your application needs
• Type of Crystal Oscillator: based on the frequency stability you are aiming for
• Operating Voltage: based on which input voltage your system applies
• Output Performance: based on your budget
• Package Adoption: based on the size of your application
  

Where To Get a Crystal Oscillator?

There are a lot of crystal oscillator manufacturers in the world today, and the number keeps growing. However, if you need a crystal oscillator circuit in your application or electronic device, it is advisable to check all the above criteria.

Most manufacturers of this electronic component factor in the operating frequency, output, and other specifications, and some do not. If you are looking for high-quality crystals that meet your industrial application needs, you should consider getting in touch with BD Electronics Ltd. It is a European Crystal oscillator distributor that can meet any of your requirements, including other electronic components.