MAGNETIC TUNNEL JUNCTION ANTIFUSE CIRCUIT COMPRISING PARALLEL CONNECTED REFERENCE MAGNETIC TUNNEL JUNCTIONS TO PROVIDE AN OPTIMUM REFERENCE RESISTANCE

摘要

An antifuse circuit (10) provides on a per bit basis a signal that indicates whether an MTJ (magnetic tunnel junction) antifuse (18) has been previously programmed to a low resistance state in response to a program voltage. A sense amplifier (12) provides the resistance state signal. A plurality of reference magnetic tunnel junctions (16) are coupled in parallel and to the sense amplifier (12), each (50, 52, 54) having a resistance within a range to provide a collective resistance that can be determined by the sense amplifier (12) to differ from each resistance state of the MTJ antifuse (18). A write circuit selectively provides a current sufficient to create the program voltage when the write circuit (20) is enabled to program the antifuse magnetic tunnel junction (18). Upon detecting a change in resistance in the MTJ antifuse (18), the write circuit (20) reduces current supplied to the antifuse (18). Multiple antifuses may be programmed concurrently. Gate oxide thicknesses of transistors are adjusted for optimal performance.