Crystal oscillators play a crucial role in electronic engineering ensuring precision and frequency control in various devices. These oscillators are electronic circuits which use vibrating crystals like quartz for mechanical resonance which helps to generate electrical signals with precise frequency. It is also to be noted that frequency produced by these crystals are stable even under varying conditions, making them the ideal option for the applications that require accurate frequency. Hence, this blog explores the essential things you need to know about crystal oscillators and its frequencies.
Crystal Oscillator Frequency – Overview:
The frequency range of crystal oscillators includes several aspects. Firstly, manufacturers make crystal oscillators at a fixed frequency range, providing different crystals that work similarly but have different main frequencies. Second, the overall range of frequency in the crystal oscillators covers a broad spectrum, starting from at the lowest 0.0320 MHz to over 1075 MHz. Keep reading the blog as we discuss the different frequency ranges of crystal oscillators.
The normal frequency in a crystal oscillator is designed previously and expected to resonate at that particular frequency. For instance, if an oscillator is designed to resonate at 10 MHz then the normal frequency of the oscillator will be 10 MHz. However, given the circumstances and usage, the oscillators can have variations in the frequencies. These changes in the frequencies are measured by frequency stability which is listed in the product’s datasheets.
The predetermined frequency at which the oscillators resonate are very stable as they result based on the crystal size. In addition, the frequency at which they resonate are stable is measured as ppm or parts per million which is far better than the unstable frequencies of the LC or RC oscillators. The standard frequencies that oscillators resonate covers a range of applications by meeting its needs and requirements.
Impact On Crystal Oscillator Frequencies
One of the foremost factors that affect the crystal oscillator’s frequency is the temperature as the crystal’s size greatly depends on the temperature. Hence, to reduce the effect, the oven-controlled crystal oscillators (OCXOs) and temperature-compensated crystal oscillators (TCXOs) are highly used in various applications in order to maintain the frequency stability under varying temperatures. In addition, there are some crystals known as cuts which are oriented in a particular way in which frequency stability is high except the need for accurate measurements.
It is possible to produce frequencies of wide range from one reference frequency using frequency dividers, frequency multipliers, and phase-locked loop circuits.
Tolerance Vs Frequency Range:
When you look into a datasheet of a crystal oscillator, you might see a frequency range listed as “10-50 MHz.” It doesn’t mean a single crystal can operate across this entire range. Instead, it refers to different crystals within that group, each with its specific frequency. For example, a crystal running at 20 MHz differs from one at 25 MHz.
In addition, each crystal has a frequency tolerance, which shows how precise each unit is. Hence, if you purchase several 25 MHz crystals with 20 ppm tolerance rate, their actual frequencies lie from 24.9995 MHz to 25.0005 MHz.
Frequency Trends In Crystal Oscillator:
As we have learnt that there are different frequency ranges, below listed are the frequency ranges categorized from low to high.
Low (32 kHz to 1 MHz) – Quartz wristwatches, Real-time clock modules, RFID systems, and Consumer electronics.
Intermediate (1 to 10 MHz) – Microcontrollers, TV remote controls, Digital circuits, Communication devices.
High (10 to 100 MHz) – Microprocessors, Wireless devices, Fast digital circuits, High-speed ADCs.
Very High (Above 100 MHz) – Advanced communication systems, Ethernet, Radar systems, Satellite communication.
However, there are exceptions: some high-frequency crystals are used in clocks, and some low-frequency crystals are used in electronic communication. In some cases, crystal oscillators are made for a particular purpose or requirement. For example, an oscillator with 4.194304 MHz is ideal for timers because this frequency is divided by 222 which yields 1 Hz signal. This was possible by 22-stage binary divider. Approach Sunstream for your RF (Radio Frequency) designs where our experts use Cadence Allegro PCB and OrCAD PCB designer. Our experts ensure to optimize power, space, and energy for many applications.