Dynamically variable electronic delays for ultrasound imaging

A novel programmable delay line system (Patent 67595-A/89 from the Ministero dell'Università e della Ricerca Scientifica e Tecnologica, Italy) for electronic control of delay profile in ultrasound real-time imaging systems is described. The line consists of a number of LC filters. The capacitance is obtained by using varicap diodes, so that electronic control over the desired depth is obtained by changing the diode inverse polarization voltage. This delay line exhibits a dramatic simplification and a broader time delay excursion than alternative techniques. Based on computer simulations, a delay line system was designed and integrated into an annular transducer-based echographic apparatus.