Abstract: A phased array ultrasound apparatus comprises an array of ultrasound transducer elements; a plurality of first electrodes and a plurality of second electrodes, such that each transducer element is associated with a first and a second electrode; wherein each transducer element comprises a layer of piezoelectric material between each of the first and the second electrodes to induce emitting of an ultrasonic wave based on control signals, wherein control signals are shared by the transducer elements; wherein a phase of an emitted ultrasonic wave differs approximately 180° between two polarization states of the piezoelectric material; and wherein the phased array ultrasound apparatus is configured to individually change polarization state of the piezoelectric material of selected ultrasound transducer elements before activating at least a subset of the ultrasound transducer elements in the array to form a combined ultrasonic wave.