Design of a Simplified Delay System for Ultrasound Phased Array Imaging

Abstract

A novel technique for implementing the dynamically vari- able delay system, required for electronic sector scanning in ultrasound phased-array imaging equipments, has been recently introduced. The technique is based on separate and independent processing of the car- rier and of the envelope of the echo pulses. Carrier phasing is accom- plished by electronic phase-shifters, while envelope delay is varied by delay lines. This latter function, however, can be performed using dw Crete delays in increments much larger than those required by previous techniques. Extensive computer simulations of the array directivity pattern have been performed to evaluate the effect of a coarse delay quantization. Based on the simulation results, the design of a delay sys- tem exhibiting a dramatic simplifkation over alternative techniques is described.