United Technologies Corporation

Michael J Barry

Harry N Gardner

Michael D Lahey

Debra S Harris

A high reliability logic circuit designed to withstand a single event upset (SEU) induced by an ion transitioning through a semiconductor structure is embodied in a memory circuit which includes a first memory cell and a second memory cell. The first and second memory cells receive a first input signal and a second input signal. The memory cells contain a logic circuit for producing a logic signal output driven by either a pullup or pulldown driver when the first and second input signals are of a desired logic state and produces a high impedance output if either input signal is not of their respective desired logic states. The memory cells also have sufficient nodal capacitance such that the output from the first or second memory cell will not be corrupted by an SEU in the logic circuit of either the first or second memory cell. The outputs of the first memory cell and second memory cell are further summed in analog fashion to produce a single output from the memory circuit. The summing of the output signals from the first and second memory cell prevents a single error in either memory cell from propagating to a next stage.

High reliability logic circuit for radiation environment

A memory cell employs four interconnected modules, each having two inputs and a truth table that has a logic level for input states and provides for a high impedance output state for unallowed states which differ from an allowed state by the status of one input. The interconnection is such that each module of a pair has as inputs the outputs of both members of the other pair, so that if one module changes state, the inputs to the members of the other will be in one of the unallowed states that produces a high impedance output. Thus, a radiation induced change of state in one module will not propagate through the system, but will be restored to an allowed state by action of the unaffected modules.

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Colorado Springs, CO, United States of America

Michael J Barry