On Concurrent Error Detection of Asynchronous Circuits Using Mixed-Signal Approach

B. Ravi KISHORE  Takashi NANYA  

IEICE TRANSACTIONS on Information and Systems   Vol.E80-D   No.3   pp.351-362
Publication Date: 1997/03/25
Online ISSN: 
Print ISSN: 0916-8532
Type of Manuscript: Special Section PAPER (Special Issue on Asynchronous Circuit and System Design)
Category: Completion-Detection & Checking
concurrent error detection,  QDI circuits,  current sensing,  built-in current sensors,  

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In the data path circuits of asynchronous systems, logical faults may first manifest as undetectable, transient wrong codewords, in spite of encoding the inputs and the outputs and proper organization which enables the faults to be propagated to the primary outputs in the form of non-codewords. Due to this, the conventional methods of concurrent error detection (CED) using the logic (voltage) monitoring is not effective. In this paper, we suggest a mixed-signal approach to achieve CED for a class of asynchronous circuits, known as self-timed circuits. First, we show that it is impossible to guarantee the CED using logic monitoring of the primary outputs in spite of proper encoding and organization of self-timed circuits. Then, we discuss different manifestations of single stuck-at faults occurring during normal operation in these circuits. Finally, we present the feasibility of achieving CED using a built-in current sensor (BICS) along with encoding techniques.