As we mentioned in “5 Key Criteria for Crystal Oscillator Selection”, a crystal oscillator is a frequency element that can stabilize the frequency and make an electronic circuit more accurate in time. Every electronic circuit that is critical to frequency stabilization is crystal/crystal oscillator needed. Hence, there are plenty of crystal oscillator applications. In this article, we have chosen the most relevant five applications, which include consumer electronics, measurement, industrial, automotive, and space applications.
Consumer Electronics Applications
Crystal oscillators (at least one crystal oscillator) are required in almost every electronic system for the system to operate normally. Among them, consumer electronic systems are one of the main sectors that crystal oscillators apply to.
Time accuracy is the most important reason that crystal oscillators are essential in consumer electronic systems. For instance, when a microprocessor-based system gives or receives commands, stores or sends data, or communicates with other devices through external interfaces, a crystal oscillator (or more than one oscillator) is needed to work as a clock signal to ensure these operations running smoothly.
In general, different clock frequencies are applied to various systems. For a computer, a 15 MHz clock input is capable of providing multiplying clocks for its subsystems. Other than that, an Ethernet controller requires a 25 MHz clock, and a real-time clock requires a 32.768 kHz clock. It is worth mentioning that TCXO is the most widely used crystal oscillator in consumer electronics applications due to its great performance and effective cost.
Since crystal oscillators are used to stabilize the frequency, measuring equipment that creates or measures frequency such as frequency generators and spectrum analyzers need crystal oscillators inside as internal frequency standards. An internal frequency standard is usually called a time base standard, and it directly determines the accuracy of the measuring equipment.
Time base standards can be affected by several factors and uncertainties might happen. Overall, the time base uncertainties are mainly categorized into temperature effects, mechanical effects, and time-related uncertainty. Temperature and mechanical effects are easy to understand, and time-related uncertainty can be roughly divided into short-term stability and long-term aging. Short-term stability is affected by any noise happening within 1 second, and it can be eliminated by averaging the noise over time. On the other hand, relaxation of mechanical stress, impurity fluctuation, and material movements can cause long-term aging.
|Time base uncertainties|
- Short-term stability
- Long-term aging
|Uncertainty in relation to time:
- Shock and vibration
In summary, time base uncertainties from any crystal oscillator should be well controlled to ensure the measuring equipment is in good condition with acceptable accuracy.
Crystal oscillators can be applied to plenty of applications in the industrial field, for instance, sensors, digital systems, communication systems, and so on. Similar to those in consumer electronics applications, crystal oscillators in industrial applications also make the systems function properly and accurately. The clock signals created by crystal oscillators can let embedded systems manage the power supply noise better and keep the systems remain stable. Other than that, a kind of programmable crystal oscillator with I2C protocol is suitable for sophisticated embedded systems in the development stage.
Crystal oscillators can be found everywhere in automobile systems, and for sure they need automotive qualification. The several main automotive standards are IATF 16949, AEC-Q100, and AEC-Q200, and it requires different grades of qualification for different systems in an automobile. In the standards, the temperature is one critical requirement that largely affects the performance of crystal oscillators. Normally, Automotive Grade 1 which ranges from -40 to 125oC is used the most widely.
|Commercial, Automotive Grade 4||0 - 70°C|
|Industrial, Automotive Grade 3||-40 - 85°C|
|Extended Industrial, Automotive Grade 2||-40 - 105°C|
|Automotive Grade 1||-40 - 125°C|
|Automotive Grade 0||-40 - 150°C|
Speaking of crystal oscillators in automotive applications, you cannot skip GPS. A GPS probably is one of the automotive systems with the highest demand of accuracy, and it is interesting that many important parameters of crystal oscillators largely impact the accuracy of the GPS. The table below shows how the oscillator parameters correspond to the GPS performance parameters.
|Crystal oscillator parameter||GPS performance parameter|
|Warm up time||Time to first fix|
|Short-term stability |
(0.1 - 100 seconds)
|A range measurement accuracy, acceleration performance, jamming resistance|
|Short-term stability (-15 minutes)||Time to subsequent fix|
|Phase noise ||Jamming margin, data demodulation, tracking|
(Source: IEEE Long Island Chapter)
Crystal oscillators can also be put in satellites for many key uses, such as precise time tracking, message transmission, etc. The accuracy requirement of satellites is more extreme than other devices since it is related to explicit real-time positioning and data transmission. Besides, the environment in outer space is harsher and the ambient temperature might affect the frequency of crystal oscillators. Therefore, oven-controlled crystal oscillators (OCXO) are the most suitable oscillators for space applications as each of them has an “oven” to heat the crystal and keep it remain its temperature to avoid ambient interference. OCXO can bring satellites and other space-related applications into a new era.
Find crystals/crystal oscillators at TECHDesign
Now at TECHDesign, you can find crystals and crystal oscillators provided by the world-leading supplier Aurum. With more than 20 years in the electronics industry, Aurum is dedicated to delivering the most reliable frequency control solutions to the public. So, what are you waiting for? Come visit TECHDesign and search for suitable crystals and oscillators for your design!