PSPICE implementation for designing the acoustical matching layers of ultrasonic piezoelectric transducers

Ultrasound has become an effective and practical tool for obtaining medical information from within the human body without exposing the patient to X-rays. The emphasis of this paper is on the design of low-loss (high transmitting power) and wide-band transducers used for ultrasonic diagnostic. The approach we have used consists of impedance matching the front face of the transducer to the propagating medium and air-backing the rear face. By tuning the thickness and acoustical impedance of the matching layer, transducers with wide-band and high-transmitting-power can be obtained. PSPICE code of the KLM model is implemented to predict precisely the performance of the matched transducers. Since the transducer's characteristics of wide-band width and high-transmitting-power are somewhat in conflict in the design criteria, a matching-layer thickness that is a little bit shorter or longer than one quarter wavelength is proposed as a good trade-off between the two criteria. Good agreement between the simulation results and experimental results has been achieved.