Real Intent, Inc.

Vishnu Vimjam

Prakash Narain

Sanjeev Mahajan

Vikas Sachdeva

Oren Katzir

Paul Vyedin

Methods and systems are described to identify potential failures caused by metastability arising from signal propagation between asynchronous clock domains in integrated circuits with multiple operating modes, each mode allowing selected clocks to propagate. Typical integrated circuits have numerous operating modes, and hence numerous possible clock combinations, each combination causing different asynchronous clock-domain crossings, and hence different potential failures. Since verification for even one clock combination is time-consuming, explicitly enumerating and verifying all possible clock combinations is unviable. In practice very few clock combinations are verified, possibly missing failures. The present invention achieves superior performance, scalability, comprehensiveness and precision in verification despite numerous operating modes, due the following insights: (a) The number of possible clock combinations for a transmit-receive signal pair is small relative to the total number of operating modes, and (b) Cause of failure for a transmit-receive pair remain identical across many clock combinations associated with it.

Methods for identifying integrated circuit failures caused by asynchronous clock-domain crossings in the presence of multiple modes

Integrated circuit failures caused by metastability related to assertion of asynchronous resets frequently escape detection before fabrication, causing design respins and severe economic loss. The numerous reset signals, flip-flops and complex logical interactions inherent in an integrated circuit cause an analysis for reset-metastability failures to be extremely noisy, reporting an unmanageable number of false failures and making early removal of failures impractical. Said noisy reporting arises because many flip-flops where reset-metastability manifests do not necessarily cause overall failure. An effective analysis of reset-metastability failures must identify all potential failures, but also must only report true failure potential. The present invention maximizes noise reduction by applying special conditions to identify flip-flops manifesting reset-metastability without causing integrated circuit failure, which can thereby be deemed safe. By reporting only true failure potential, the present invention enables efficient, robust and error-free removal of reset-related failures from an integrated circuit prior to fabrication.

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Vishnu Vimjam