Superconducting Ring BIST for Latency-Independent Fault Testing
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Solution Overview
Problem
Superconducting circuitry requires testing at cryogenic temperatures, making it challenging to diagnose assembly faults and localize issues in superconducting rings without prior knowledge of interchip connection latencies, and existing testing methods are not scalable for large systems.
Innovation Solution
The implementation of a built-in self-test (BIST) circuitry in superconducting rings, which includes controller circuitry, self-test logic, and error counters, allows for testing and error characterization without prior latency determination, enabling fault localization and system tuning for minimal bit error rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional testing methods are used for superconducting rings, then fault detection is possible, but extensive latency testing is required which increases test time and complexity
Solution Approach 1:
The BIST circuitry is pre-configured with test data patterns and comparison logic before actual testing begins. The system prepares test sequences, pseudorandom patterns, and error detection mechanisms in advance, eliminating the need for extensive latency testing during operation. This preliminary setup enables immediate fault detection without time-consuming measurement sequences.
Solution Approach 2:
The superconducting ring system performs self-diagnosis through integrated BIST circuitry that generates its own test data, conducts comparisons, and detects errors autonomously. The system serves its own testing needs by incorporating transmitters, receivers, comparators, and error counters within the ring structure itself, eliminating external testing equipment and reducing test time.
2Reliability
If traditional testing methods are used for superconducting rings, then faults can be detected, but the testing process becomes complex and not scalable to large systems
Solution Approach 1:
The testing system is divided into modular BIST circuitry units distributed across different ring stops. Each unit contains localized test data generation, transmission, reception, and comparison capabilities. This segmentation allows independent testing of individual segments and enables scalable expansion to larger systems without proportionally increasing overall complexity.
Solution Approach 2:
The BIST circuitry is designed with universal functionality that can operate in multiple modes: as transmitters generating test data, as receivers detecting errors, and as comparators validating data integrity. This multi-functionality reduces the need for separate dedicated testing components, simplifying the overall testing process while maintaining comprehensive fault detection capability across the superconducting ring system.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables efficient fault diagnosis and system optimization by characterizing channel integrity and bit-error rates within superconducting rings, facilitating repair and improving overall system performance without the need for extensive latency testing.
Implementation Method 1
superconducting circuitry, operating temperatures of around 4 kelvins
Implementation Method 2
superconducting Josephson junctions (JJs)
Data Source
AI summary
Ring packet built-in self-test (PBIST) circuitry configured to detect errors in wires connecting a ring of superconducting chips includes circuitry configured to make the PBIST immune to interchip latency and still allow the PBIST to test a stop-to-stop connection. By making a PBIST independent of latency, an entire ring can be characterized for latency and for its bit-error rate prior to running any functional test. Such systems and associated methods can be scaled to larger platforms having any number of ring stops. The PBIST circuitry can function as either transmitter or receiver, or both, to test an entire ring. The PBIST can also be used to tune clocks in the ring to achieve the lowest overall bit error rate (BER) in the ring.