The effect of cell-to-cell variation in CMUTs on quality factor and frequency noise

This study aims to examine multi-resonator properties and analyze the effects of cell-to-cell variation on device quality factor and oscillator frequency noise. A CMUT element was modeled as parallel connection of multiple conventional 4-circuit elements and cell-to-cell variation was estimated by comparing the model’s parallel Q factor with the experimentally measured Q factor. Additionally, series and parallel resonance circuits were implemented by using the modeled CMUT. The frequency noise was quantitatively measured by using the Allan deviance method. The short-term noise of the series resonance oscillator is much higher than that of the parallel resonance oscillator. However, the long-term noise of the oscillator is not highly affected by the topology of the circuit.