Multi-stage test response compactors

US7818644B2 · kind B2 · utility

Inventors

• Janusz Rajski · West Linn, US
• Jerzy Tyszer · Poznań, PL
• Grzegorz Mrugalski · Ostróda, PL
• Mark Kassab · Wilsonville, US
• Wu-Tung Cheng · Lake Oswego, US

Key dates

• Filing date: Feb 20, 2007
• Grant date: Oct 19, 2010
• Expiry date: Jan 24, 2028

Classification

• Technology area (CPC G): Physics
• CPC primary: G01R31/318566
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

Disclosed herein are exemplary embodiments of a so-called “X-press” test response compactor. Certain embodiments of the disclosed compactor comprise an overdrive section and scan chain selection logic. Certain embodiments of the disclosed technology offer compaction ratios on the order of 1000×. Exemplary embodiments of the disclosed compactor can maintain about the same coverage and about the same diagnostic resolution as that of conventional scan-based test scenarios. Some embodiments of a scan chain selection scheme can significantly reduce or entirely eliminate unknown states occurring in test responses that enter the compactor. Also disclosed herein are embodiments of on-chip comparator circuits and methods for generating control circuitry for masking selection circuits.