On-line testing of globally asynchronous circuits

Abstract

The problem of on-line testing of asynchronous circuits is analysed, several infrastructures are proposed and a selfchecking tree checker is designed. The checker uses ondemand self-test, which reduces power consumption and guarantees bounded self-test period. Objects under test are tested by observing protocols at their primary inputs and outputs. The checker does not slow down the functional system, as it only samples the signals. The protocols are checked by identifying enabled and refused signal transitions in each state of the system. The fault coverage of internal faults of the checker is calculated. Simulation results are included.

A Discrete Event System Approach to Online Testing of Speed Independent Circuits

“…In our experiments, we have considered some standard SI benchmark circuits [32]. Further, for comparison, we have also implemented our scheme on the circuits used in [5].…”

“…The approach of self-checking design consists of encoding the circuit outputs using some error detecting code and then checking some code invariant property (e.g., Parity) [3][4][5]. Some examples are Parity codes [6], m-out-of-n codes [7], and so forth.…”

“…Most of the papers cited in the above discussion are for OLT of synchronous circuits and only a few of them [4,5,10] are applicable to asynchronous circuits. Now, we elaborate on these three works on OLT of asynchronous circuits and derive motivation of the present work.…”

“…Further, both being the same circuit, they are susceptible to similar nature of failures. The schemes reported in [4,5] basically work by checking whether the output of the asynchronous circuit maintains a predefined protocol (i.e., there is no premature or late occurrence of transitions). The checker circuit is implemented using David cells (DCs), Mutual Exclusion (Mutex) elements, C-elements, and logic gates.…”

“…The fourth and fifth circuits have been used in [5]. The others are standard asynchronous benchmarks [32] which are complex in terms of area, states, and signal compared to first five circuits in the table.…”