Directional, non-volatile bistable resistor logic circuits

Abstract

Abstract A circuit consisting of a pair of bistable resistors connected in series at a node to which current may be applied and from which current may be drawn and having a source of potential connected to each bistable resistor is disclosed. The bistable resistors are oriented physically in the same direction such that current in a given direction which exceeds a threshold and which switches the bistable resistors into a high resistance state can be characterized as the forward direction. Conversely, current in the opposite direction to the given direction which, when it exceeds a threshold, switches the devices from a high resistance state into a low resistance state can be characterized as the backward direction. With appropriately applied potentials to each of the bistable resistors, with one potential more positive than the other, current can be made to flow in the forward and backward directions. In the forward direction, both resistors are switched into or remain in a high resistance or RH state. When current flows in the backward direction through the pair of bistable resistors, they switch into or remain in the low resistance or RL state. By applying the same potentials to the bistable resistors and causing current to flow into or out of the node at which the bistable resistors are connected, it is possible to cause the pair of resistors to assume a low resistance high resistance state and, a high resistance low resistance state, respectively. Thus, by simply controlling the potentials and the direction of current flow through each of the pair of bistable resistors, four, non-volatile, stable states are achievable as opposed to a maximum of two volatile states in similarly arranged tunnel diode circuits, for example. Because the arrangements shown are inexpensive, easy to fabricate and permit high packing densities, circuits such as shift registers which utilize large numbers of similarly arranged logic circuits are most attractive. In addition, the nanosecond switching speeds available in bistable resistors make them superior to other known switching devices of slower switching speed. A shift register circuit incorporating three of the four non-volatile, stable states available with the logic circuits is also disclosed. The shift register utilizes a low resistance-high resistance state to represent a binary ''''one'''' and a high resistance-high resistance state and a high resistance-low resistance state to represent a binary ''''zero.

Inventors

• 👤 P Krick
• 👤 P Pleshko

Bibliographic Details