Bruno Studer

Batch fabrication of AT-cut crystal resonators up to 200 MHz

AT-cut High Frequency Fundamental quartz resonators have been fabricated up to 200 MHz. Specific problems relating to this range of frequency like the fabrication process or the design of the electrodes are presented. Finished devices have a resistance lower than 20 Ohms, exhibit only few weak spurious modes and are stable during an accelerated ageing measurement.

Ultra small AT-cut quartz resonators at 155.52 MHz made by a batch process

AT-cut High Frequency Fundamental mode quartz resonators at 155.52 MHz have been fabricated using a batch process. The devices are 0.82 mm wide and 2.7 mm long. Specific problems like quality factor or flexure modes relating to the small size of the device are presented. The quality factor of finished devices can be as high as 50000 with a C1 of 1fF. Devices with a C1 of 4fF have a series resistance of 40 W. Accelerated ageing measurement shows a good stability of the frequency while thermal measurement does not show the presence of activity dips.

High and low frequency GaPO/sub 4/ resonators

High frequency fundamental inverted mesa resonators with large pulling range have been produced in crystalline GaPO/sub 4/. Motional capacitances at least 3 times larger than those of equivalent quartz resonators have been achieved for resonators with a fundamental frequency up to 155 MHz. High frequency resonators behave as a function of temperature as expected. Low frequency miniature tuning fork resonators have been produced as well. Their electrical and thermal parameters are similar to those of standard quartz crystal tuning forks, however the thermal compensation is not as good as expected from theory.