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J. Maier, A. Steininger:
"Online Test Vector Insertion: A Concurrent Built-In Self-Testing (CBIST) Approach for Asynchronous Logic";
Talk: 17th Symposium on Design and Diagnosis of Electronic Circuits and Systems (DDECS 2014), Warschau, Polen; 2014-04-23 - 2014-04-25; in: "Design and Diagnostics of Electronic Circuits Systems (DDECS), 2014 IEEE 17th International Symposium on", (2014), 6 pages.

Complementing concurrent checking with online testing is crucial for preventing fault accumulation in fault tolerant systems with long mission times. While implementing a non-intrusive online test is cumbersome in a synchronous environment, this task becomes even more challenging in asynchronous designs. The latter receive increasing attention, mainly due to their elastic timing behaviour; however the issues related with their testing remain a key obstacle for their wide adoption.
In this paper we present a novel approach for testing of asynchronous circuits that leverages the redundancy present in the conventional 4-phase protocol for implementing a fully transparent and fully concurrent test procedure. The key idea is to use the protocol´s unproductive NULL phase for processing test vectors, thus effectively interleaving the incoming 4-phase data stream with a test data stream in a 2-phase fashion. We present implementation templates for the fundamental building blocks required and give a proof-of-concept by an example application that also serves as a platform for evaluating the overheads of our solution which turn out to be moderate.