Experimental Investigation of the Temperature and Power Handling Performance of a 2.3GHz AlN Based LCAT Mode Resonator

This work reports the characterization results of the temperature coefficient of frequency (TCF), as well as the power handling capability of a 2.3GHz AlN based LCAT mode resonator, which is formed by sandwiching a 1μm-thick aluminium nitride (AlN) layer between two groups of top molybdenum (Mo) interdigitated electrodes (IDEs) and two groups of bottom Mo IDEs. The thickness of both top and bottom electrodes is 0.2μm. By having this type of electrode configuration, adjacent IDE fingers on the same side of AlN film are capable of exciting a lateral mode, while top and bottom IDE fingers are capable of exciting a thickness mode. Synergetic coupling of the constituting thickness mode and lateral mode yields high effective electromechanical coupling coefficient (k
²
_eff
). Experimental results show that when the input power to the resonator is set at 0dBm during testing, a TCF of 24.5pμm/°C across the temperature range of -40°C to 120°C is obtained. While the temperature for testing is fixed at 20°C, no bifurcation is observed up to the input level of +18 dBm, whereas minimum distortion can be observed in the frequency response of the resonator's impedance under different input power level, demonstrating excellent power handling capability and great potential in next-generation RF communication applications.