In this letter, a 2.5 MHz 320-element 1.5D active matrix phased-array ultrasound transducer was designed and fabricated using high-temperature relaxor-based piezoelectric ternary Pb(In1/2Nb1/2)O-3-Pb (Mg1/3Nb2/3)O-3-PbTiO3 (PIN-PMN-PT) single crystal