ATcut

AT-cut is a quartz crystal cut widely used for frequency-control resonators in electronic oscillators. The cut is produced by rotating the crystal around a crystallographic axis (approximately the X-axis) by about 35 degrees relative to a standard plane, which yields a thickness-shear mode that is suitable for stable vibration. This orientation results in favorable piezoelectric characteristics and practical manufacturability.

A primary feature of the AT-cut is its relatively low first-order temperature coefficient near room temperature, offering good short-term frequency stability for a wide range of applications. The frequency–temperature relationship is roughly parabolic, with drift increasing away from ambient temperature. This makes AT-cut crystals well suited for devices that operate in environments with modest temperature variation.

AT-cut crystals are used in a broad range of devices, including crystal oscillators for watches, clocks, radios, microcontrollers, and telecom equipment. They can operate in fundamental or overtone modes and are manufactured in various package styles, such as through-hole or surface-mmount configurations. Typical frequencies span from a few kilohertz to several tens of megahertz, with 32.768 kHz watch crystals being a common application.

Compared with other cuts, such as BT-cut or SC-cut, AT-cut offers a favorable balance of temperature stability, ease of fabrication, and cost. SC-cut crystals provide superior temperature stability and aging performance but at higher cost and with more complex processing, while BT-cut variants emphasize different mechanical properties or frequency ranges.

Manufacturing involves precise sawing and lapping to achieve the desired orientation, followed by electrode deposition and encapsulation in metal housings or low-profile packages suitable for surface-mount or through-hole assembly.