Calculation of ultrasonic transducer signal-to-noise ratios usingthe KLM model

摘要

This paper describes a method for adding thermal and amplifiernnoise to a KLM model for a transducer element. The model is used toncompare the magnitudes of various noise sources in a 5 MHz array elementntypical of those used for linear array imaging with and without annamplifier. Fundamental signal-to-noise ratio (SNR) issues of importancento array and amplifier designers are explored, including the effect onnSNR of effective dielectric constant of the piezoelectric material,nindividual element size, changing the number of elements, and adding annamplifier to an element before and after a cable. SNR is considered bothnfor the case in which the acoustic output is limited by the maximumnrarefactive pressure which is considered safe for a particularnapplication (Mechanical Index limitation) and the case in which acousticnoutput is limited by the maximum transmit voltage than can he deliverednby the imaging system or tolerated by the transducer. It is shown thatnthe SNR performance depends on many controllable parameters and thatnsignificant improvements in SNR can be achieved through proper design.nThe implications for 1.5-D and 2-D array elements are discussed