Amplitude-frequency effects of Y-cut langanite and langatate

Amplitude-frequency effects of a y-cut langanite (LGN) resonator and a y-cut langatate (LGT) resonator were measured. The frequency shifts from the baseline frequency with 1 mA were measured as a function of drive currents up to 28 mA. While high drive current shifted the frequency, it also heated the crystal locally, causing temperature-related frequency changes. The local heat transfer and its influence on the frequency were analyzed. The amplitude-frequency shift was effectively measured, not affected by the temperature-related frequency changes. It is found that the 3^rd, 5^th, and 7^th overtones (OT´s) behave as soft springs, i.e., resonant frequency decreases as drive current increases. The drive sensitivity coefficients of the 3^rd and 5^th OT´s are in the vicinity of -2 ppm/(current density in [mA/mm²])² or -2 ppb/(current in [mA])² for both resonators. The 7^th OT´s are higher than the other OT´s: -5∼-7 ppb/mA². The lowest drive sensitivity is -1.2 ppb/mA² on the 5^th OT of the LGT.