6 research outputs found
Automatic test pattern generation for asynchronous circuits
The testability of integrated circuits becomes worse with transistor dimensions reaching nanometer
scales. Testing, the process of ensuring that circuits are fabricated without defects, becomes
inevitably part of the design process; a technique called design for test (DFT). Asynchronous
circuits have a number of desirable properties making them suitable for the challenges posed
by modern technologies, but are severely limited by the unavailability of EDA tools for DFT
and automatic test-pattern generation (ATPG).
This thesis is motivated towards developing test generation methodologies for asynchronous
circuits. In total four methods were developed which are aimed at two different fault models:
stuck-at faults at the basic logic gate level and transistor-level faults. The methods were
evaluated using a set of benchmark circuits and compared favorably to previously published
work.
First, ABALLAST is a partial-scan DFT method adapting the well-known BALLAST technique
for asynchronous circuits where balanced structures are used to guide the selection of
the state-holding elements that will be scanned. The test inputs are automatically provided
by a novel test pattern generator, which uses time frame unrolling to deal with the remaining,
non-scanned sequential C-elements. The second method, called AGLOB, uses algorithms
from strongly-connected components in graph graph theory as a method for finding the optimal
position of breaking the loops in the asynchronous circuit and adding scan registers. The
corresponding ATPG method converts cyclic circuits into acyclic for which standard tools can
provide test patterns. These patterns are then automatically converted for use in the original
cyclic circuits. The third method, ASCP, employs a new cycle enumeration method to find the
loops present in a circuit. Enumerated cycles are then processed using an efficient set covering
heuristic to select the scan elements for the circuit to be tested.Applying these methods to
the benchmark circuits shows an improvement in fault coverage compared to previous work,
which, for some circuits, was substantial. As no single method consistently outperforms the
others in all benchmarks, they are all valuable as a designer’s suite of tools for testing. Moreover,
since they are all scan-based, they are compatible and thus can be simultaneously used in
different parts of a larger circuit.
In the final method, ATRANTE, the main motivation of developing ATPG is supplemented by
transistor level test generation. It is developed for asynchronous circuits designed using a State
Transition Graph (STG) as their specification. The transistor-level circuit faults are efficiently
mapped onto faults that modify the original STG. For each potential STG fault, the ATPG tool
provides a sequence of test vectors that expose the difference in behavior to the output ports.
The fault coverage obtained was 52-72 % higher than the coverage obtained using the gate
level tests. Overall, four different design for test (DFT) methods for automatic test pattern generation
(ATPG) for asynchronous circuits at both gate and transistor level were introduced in this thesis.
A circuit extraction method for representing the asynchronous circuits at a higher level of
abstraction was also implemented.
Developing new methods for the test generation of asynchronous circuits in this thesis facilitates
the test generation for asynchronous designs using the CAD tools available for testing the
synchronous designs. Lessons learned and the research questions raised due to this work will
impact the future work to probe the possibilities of developing robust CAD tools for testing the
future asynchronous designs
DATICS-2010: Welcome message from workshop organizers: FutureTech 2010
link_to_subscribed_fulltex
Preface of the 2010 IAENG International Conference on Electrical Engineering special session: Design, analysis and tools for integrated circuits and systems
link_to_subscribed_fulltex
Estimation of tuberculosis incidence at subnational level using three methods to monitor progress towards ending TB in India, 2015–2020
Objectives We verified subnational (state/union territory (UT)/district) claims of achievements in reducing tuberculosis (TB) incidence in 2020 compared with 2015, in India.Design A community-based survey, analysis of programme data and anti-TB drug sales and utilisation data.Setting National TB Elimination Program and private TB treatment settings in 73 districts that had filed a claim to the Central TB Division of India for progress towards TB-free status.Participants Each district was divided into survey units (SU) and one village/ward was randomly selected from each SU. All household members in the selected village were interviewed. Sputum from participants with a history of anti-TB therapy (ATT), those currently experiencing chest symptoms or on ATT were tested using Xpert/Rif/TrueNat. The survey continued until 30 Mycobacterium tuberculosis cases were identified in a district.Outcome measures We calculated a direct estimate of TB incidence based on incident cases identified in the survey. We calculated an under-reporting factor by matching these cases within the TB notification system. The TB notification adjusted for this factor was the estimate by the indirect method. We also calculated TB incidence from drug sale data in the private sector and drug utilisation data in the public sector. We compared the three estimates of TB incidence in 2020 with TB incidence in 2015.Results The estimated direct incidence ranged from 19 (Purba Medinipur, West Bengal) to 1457 (Jaintia Hills, Meghalaya) per 100 000 population. Indirect estimates of incidence ranged between 19 (Diu, Dadra and Nagar Haveli) and 788 (Dumka, Jharkhand) per 100 000 population. The incidence using drug sale data ranged from 19 per 100 000 population in Diu, Dadra and Nagar Haveli to 651 per 100 000 population in Centenary, Maharashtra.Conclusion TB incidence in 1 state, 2 UTs and 35 districts had declined by at least 20% since 2015. Two districts in India were declared TB free in 2020