No abstract

For many ultrasonic testing instruments, the piezoelectric transducers are working under a pulse situation. To improve the resolution of these instruments, the designs of the transducers must be considered. Recently, some ultrasonic instruments such as blood flow instruments, a Doppler system that uses ultrasonic pulsed random signals, and spectral analysis in food ultrasonography all emit and receive wideband spike pulses, so that they need piezoelectric transducers and emission circuits with a wider frequency band and higher efficiency. In this paper use is made of a Redwood equivalent circuit and a Laplace transform to analyze the impulse response of the emitting and receiving networks for the thickness mode piezoelectric transducers. The theoretical analysis shows that the sensitivity of the acoustic system is proportional to the square of the electromechanical coupling coefficient and inverse to the flight time of the ultrasonic wave within the transducer. An ultrasonic spike pulse emission circuit for thickness mode piezoelectric transducers was installed on the basis of theoretical analysis. The experimental results are in good agreement with the theoretical results.