AbstractsComputer Science

Magnetically programmable surface acoustic wave (MP SAW) devices were designed, fabricated and characterized in this thesis using integrated giant magnetoresistive (GMR) bits with interdigital reflectors. This provides a proof of concept of a novel storage element on radio frequency identification tags. Interdigital transducers (IDTs) on a piezoelectric substrate are used to transmit and receive signals to and from the reflector, where the magnitude of the signal reflected back is dependent on the resistance state of the GMR bit. Two MP SAW device designs were considered and fabricated. Theoretical calculations were performed to determine the impedance of the IDTs and reflector, and to determine what the effects of a varying impedance load on the reflector would have on the reflection response of the MP SAW device. Programmable switching of one GMR bit has been demonstrated using an applied magnetic field strength of 10 Oe to 15 Oe. Scattering parameter measurements have been taken to determine the magnitude of the reflection response of the reflector, and a difference of 0.9% has been detected between the high and low resistance states of the GMR bit. A change in reflection response has been consistently shown in all MP SAW devices, demonstrating the feasibility of integrated magnetic elements in SAW devices as memory elements in RFID tags.