IQD crystal oscillator AT cutting method and process

In the crystal industry, as long as the crystal can meet the needs of various products, few people worry about how it is manufactured, or even exactly how it works. But sometimes, it can be useful to master the basics, even if it only eliminates some of the more exaggerated performance requirements in the data sheet. Wafers of crystals for electronic applications are cut from quartz stone. The cutting direction determines the vibration mode of the crystal, frequency-temperature characteristics, how to age and various other parameters. About 90% of all crystals used in these applications are so-called AT cut. This means that the gem is cut at an angle of 35°15' to the Z axis. Due to the temperature characteristics of the obtained [crystal oscillator ] (http://www.xtal.cc/kss.html) , AT cutting is very popular, they can use the inflection point (temperature) in the temperature range of -40°C to +125°C The symmetry point that increases or decreases with temperature) is 25°C.

When a batch of crystals must exhibit the same characteristics, the cutting angle is particularly critical. The industry standard practice here is to specify the cutting angle within ±15 seconds of degree (or 0.0042 of 1 degree). Sometimes, the cutting angle may be slightly changed on purpose to achieve the desired temperature characteristic change. As with all electronic components, parts with very tight tolerances are more expensive than parts with looser tolerances, mainly due to the limited output that can be achieved with smaller tolerances. It is interesting that the temperature-frequency characteristics of AT-cut crystals are symmetrical. This is why you will see the specifications of passive crystals are 0°C to 50°C, -10°C to +60°C, -20°C to +70°C, etc. These specified temperature ranges are at 25°C.

Therefore, it is usually used to indicate the "industrial-grade" temperature range of other electronic components, including semiconductors, from -40°C to +85°C, and is not the most appropriate method for determining crystals. The closest suitable temperature range is -40°C to +90°C. Therefore, if you see a reference design that requires a crystal with a stability of ±10 ppm in the temperature range of -40°C to +85°C, the crystal oscillator, as an important electronic component, is irreplaceable in today’s electronic equipment . It has the important characteristics of high precision and high stability, and plays an irreplaceable role in other frequency electronic components in terms of information transmission and frequency stability and time standard control. AT-cut crystal vibrators, as components that generate reference signals such as ICs, are widely used in various electronic devices such as mobile phones, smart phones, and healthcare products.