Non-volatile static random access memory using a 7t1r cell with initialization and pulse overwrite

Abstract

A non-volatile SRAM cell comprises a first inverter, a second inverter, a first access transistor, a second access transistor, and a variable resistive element. The first inverter voltage is supplied by a first differential supply. The second inverter voltage is supplied by a second differential supply. The variable resistive element coupling with a third access transistor in series is coupled to the first output node. The non-volatile SRAM cell operates in a restore operation comprising a dual supply initialization phase and a pulse-overwrite phase. During the dual supply initialization phase, the first differential supply increases before the second differential supply so as to initialize the first output node to a logic state. During the pulse-overwrite phase, the third access transistor is turned on for a switch period in order to discharge/charge the first output node.