Nonvolatile logic and security circuits

#Circuits typically experience a static current draw when power is applied due to leakage. However, powering a circuit down may be problematic as the circuitry is unable to retain the current state upon power up without lengthily power up or initialization sequences because the latch elements are typically volatile storage elements and disabling power would cause the loss of the state stored on the latch.

#The detailed description is described with reference to the accompanying figures. In the figures, the left-most digit(s) of a reference number identifies the figure in which the reference number first appears. The use of the same reference numbers in different figures indicates similar or identical components or features.

#FIG. 1 illustrates a partial logic diagram and partial circuit diagram showing select components of circuit for maintaining a state through a power off period according to some implementations.

#FIG. 2 illustrates a physical diagram showing select components of the bridge of FIG. 1 according to some implementations.

#This disclosure includes techniques and implementations to implement a nonvolatile storage element. In some examples, the magnetic random access memories (MRAMs) or spin torque MRAM (ST-MRAM) elements may be utilized to generate nonvolatile storage elements, such as nonvolatile flip flop, logic gate, or other circuit components for maintain a state associated with a circuit while a device or portion of a device is powered off. For instance, in some implementations, the nonvolatile storage elements described herein may utilize magnetic orientation opposed to a charge state to maintain a value.

#In one implementation, a nonvolatile storage element may include a plurality of restive elements or magnetic tunnel junctions (MTJs) arranged as a bridge having a pair of midpoints with pairs of MTJs positioned both above and below each of the midpoints. In some implementations, the number of pairs of MTJs above each midpoint and below each midpoint are equal. The nonvolatile flip flop also includes a read bias/write driver circuit connected to the bridge and configured to generate drive signals to cause the pairs of MTJs to be driven high or low, such that a value or state may be stored on the bridge.

#For instance, in one particular implementation, the bridge includes two pairs (or four) MTJs above the midpoints and two pairs (or four) MTJs below the midpoints. In this implementation, the read bias/write driver circuit connected to the bridge and configured to generate four drive signals (e.g., two above the midpoints and two below the midpoints) to cause the pairs of MTJs to be driven high and/or low, such that a particular voltage differential associated with the midpoints of the bridge and thereby a state associated with the particular voltage differential may be stored.