4. ultrasound transducers are composed of many different piezoelectric elements, each of which is independently controlled electronically. in addition to using that electrical independence to focus the sound waves, it can also be used to control the amplitude of the sound wave sent and received from each element. controlling these element amplitudes can be used to apodize the acoustic aperture to reduce side lobes of the focused sound wave, increasing the system’s spatial resolution. this side lobe reduction is achieved by reducing the received voltage amplitudes of the elements on the ends of the aperture relative to the center elements before they are summed together. for a 5 element ultrasound transducer (e1−5), design a summing amplifier so that two elements (e2,4) adjacent to the center element (e3) are 85% the center element’s amplitude, and the outer elements (e1,5) are 25% the center elements excitation voltage (i. e., vo = ve3 + 0.85ve2 + 0.85ve4 + 0.25ve1 + 0.25ve5 ).