Multilayer piezoelectric resonators for medical ultrasound transducers

Multilayer piezoelectric resonators were fabricated and the dependence of the electrical impedance and the coupling coefficient were measured as a function of the number of layers, for N=1, /spl middot//spl middot//spl middot/, 20 layers. The magnitude of the electrical impedance followed the theoretical predicted 1/N/sup 2/ relation, and the coupling coefficient, K/sub t/, remained relatively constant out to N=15 layers. These cofired resonators are suitable for medical ultrasound transducers.