Honeywell International Inc.

Harry H L Liu

Michael S Liu

Keith W Golke

David K Nelson

Romney R Katti

Eric E Vogt

Anuj Kohli

Owen J Hynes

A radiation hardened memory element includes at least two delay elements for maintaining radiation hardness. In an example, the memory element is an SRAM cell. Both delays are coupled together in series so that if either one of the delays fails, a delay will still be maintained within the SRAM cell. The critical areas of the delays may be positioned so that a common line of sight cannot be made between each delay and a circuit node.

Radiation-hardened memory element with multiple delay elements

A Static Random Access Memory (SRAM) having a split write control is described. The SRAM includes bit, write, and write-word lines. Each memory cell within the SRAM includes a delay which is coupled to a dedicated write-word line. When a cell is not being written, its delay receives a delay signal on its associated write-word line, which increases the response time of the cell. When a cell is to be written, however, its delay receives a bypass signal on its associated write-word line, which decreases the response time of the SRAM cell.

SRAM split write control for a delay element

A method and apparatus for regulating photocurrents is described. A photocurrent regulator may include a transistor having an associated cross-sectional area. The photocurrent regulator is coupled between an integrated circuit and a voltage source. When a dose rate event occurs within the integrated circuit, the photocurrent regulator, via the cross-sectional area, regulates a recombination path to the voltage source. Consequently, photocurrents within the integrated circuit are regulated, preventing permanent damage within the integrated circuit.

Method and apparatus for regulating photo currents induced by dose rate events

Behaviors of a transistor during a dose rate event can be modeled using a circuit simulation software package. A subcircuit model replaces a transistor in a circuit design to be simulated. The subcircuit model can be in the form of a schematic-based representation or a netlist. The subcircuit model provides a model of a source junction and a drain junction in the transistor during the dose rate event. The subcircuit model also includes the size of the transistor being replaced and the dose rate of the dose rate event. Once the transistor is replaced with the subcircuit model, a dose rate simulation may be performed to determine the dose rate hardness of the circuit design.

Simulating a dose rate event in a circuit design

A device is connected in parallel with an MTJ structure of an MRAM bit to shunt photocurrent away from and/or limit voltage across the MTJ structure during a dose rate event. The device may include at least one transistor and/or at least one diode. One device may be used to protect an entire row and/or column of MRAM bits. As a result, the MRAM bits are protected during a dose rate event.

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Maple Grove, MN, United States of America

Harry H L Liu