Leland Stanford Junior University

Signetics

Edward J McCluskey

Lewis K Russell

Nur A Touba

Subhasish Mitra

Tich T Dao

The present invention provides a word voter for redundant systems with n modules wherein each of these n modules generates a word output. The word voter receives word outputs from each of the n modules. A voter decision is generated by the word voter utilizing a word basis of the word output of each of the n modules. The voter is based on a majority voting principle. The advantage of the present invention is that the word voter can be used to design redundant systems, such as, but not limited to, TMR systems, that are protected against common mode and multiple output failures. In addition, another advantage of the present invention is that is provides for a technique to efficiently design a TMR simplex system. The present invention provides a word voter for hardware systems.

Word voter for redundant systems

A low-overhead scheme for built-in self-test of digital designs incorporating scan allows for complete (100%) fault coverage without modifying the function logic and without degrading system performance (beyond using scan). By altering a pseudo-random bit sequence with bit-fixing logic at an LFSR's serial output, deterministic test cubes that detect random pattern-resistant faults are generated. A procedure for synthesizing the bit-fixing logic allows for complete fault coverage with low hardware overhead. Also, the present approach permits the use of small LFSR's for generating the pseudo-random bit sequence. The faults that are not detected because of linear dependencies in the LFSR can be detected by generating more deterministic cubes at the expense of additional bit-fixing logic.

Altering bit sequences to contain predetermined patterns

Logic circuitry provides predetermined logic outputs in response to logical combinations of inputs. The circuitry includes a plurality of input devices for receiving logic inputs and capable of assuming conduction states in response to the logic levels of said inputs. At least one output device is connected to two or more input devices. Means having predetermined logic levels is provided connected intermediate the input and output devices for controlling the conduction state of the output devices as a function of the input devices and the predetermined logic levels.

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Palo Alto, CA, United States of America

Edward J McCluskey