Black Box Model based Self Healing Solution for Stuck at Faults in Digital Circuits

The paper proposes a design strategy to retain the true nature of the output in the event of occurrence of stuck at faults at the interconnect levels of digital circuits. The procedure endeavours to design a combinational architecture which includes attributes to identify stuck at faults present in the intermediate lines and involves a healing mechanism to redress the same. The simulated fault injection procedure introduces both single as well as multiple stuck-at faults at the interconnect levels of a two level combinational circuit in accordance with the directives of a control signal. The inherent heal facility attached to the formulation enables to reach out the fault free output even in the presence of faults. The Modelsim based simulation results obtained for the Circuit Under Test [CUT] implemented using a Read Only Memory [ROM], proclaim the ability of the system to survive itself from the influence of faults. The comparison made with the traditional Triple Modular Redundancy [TMR] exhibits the superiority of the scheme in terms of fault coverage and area overhead. 

Low Cost NBTI Degradation Detection and Masking Approaches

Performance degradation of integrated circuits due to aging effects, such as Negative Bias Temperature Instability (NBTI), is becoming a great concern for current and future CMOS technology. In this paper, we propose two monitoring and masking approaches that detect late transitions due to NBTI degradation in the combinational part of critical data paths and guarantee the correctness of the provided output data by adapting the clock frequency. Compared to recently proposed alternative solutions, one of our approaches (denoted as Low Area and Power (LAP) approach) requires lower area overhead and lower, or comparable, power consumption, while exhibiting the same impact on system performance, while the other proposed approach (denoted as High Performance (HP) approach) allows us to reduce the impact on system performance, at the cost of some increase in area and power consumption

RON-BEAM DEBUG AND FAILURE ANALYSIS OF INTEGRATED CIRCUITS

A current research project at IMAG/TIM3 Laboratory aims at an integrated test system combining the use of the Scanning Electron Microscope (SEM), used in voltage contrast mode, with a new high-level approach of fault location in complex VLSI circuits, in order to reach a complete automated diagnosis process. Two research themes are induced by this project, which are: prototype validation of known circuits, on which CAD information is available, and failure analysis of unknown circuits, which are compared to reference circuits. For prototype validation, a knowledge-based approach to fault location is used. Concerning failure analysis, automatic image comparison based on pattern recog- nition techniques is performed. The purpose of the paper is to present these two methodologies, focusing on the SEM-based data acquisition process

On Fault Diagnosis using Bayesian Networks ; A Case Study of Combinational Adders.

In this paper, we use Bayesian networks to reduce the set of vectors for the test and the diagnosis of combinational circuits. We are able to integrate any fault model (such as bit-flip and stuck-at models) and consider either single or multiple faults. We apply our method to adders and obtain a minimum set of vectors for a complete diagnosis in the case of the bit-flip model. A very good diagnosis coverage for the stuck-at fault model is found with a minimum set of test vectors and a complete diagnosis by adding few vectors

Robust low-power digital circuit design in nano-CMOS technologies

Device scaling has resulted in large scale integrated, high performance, low-power, and low cost systems. However the move towards sub-100 nm technology nodes has increased variability in device characteristics due to large process variations. Variability has severe implications on digital circuit design by causing timing uncertainties in combinational circuits, degrading yield and reliability of memory elements, and increasing power density due to slow scaling of supply voltage. Conventional design methods add large pessimistic safety margins to mitigate increased variability, however, they incur large power and performance loss as the combination of worst cases occurs very rarely. In-situ monitoring of timing failures provides an opportunity to dynamically tune safety margins in proportion to on-chip variability that can significantly minimize power and performance losses. We demonstrated by simulations two delay sensor designs to detect timing failures in advance that can be coupled with different compensation techniques such as voltage scaling, body biasing, or frequency scaling to avoid actual timing failures. Our simulation results using 45 nm and 32 nm technology BSIM4 models indicate significant reduction in total power consumption under temperature and statistical variations. Future work involves using dual sensing to avoid useless voltage scaling that incurs a speed loss. SRAM cache is the first victim of increased process variations that requires handcrafted design to meet area, power, and performance requirements. We have proposed novel 6 transistors (6T), 7 transistors (7T), and 8 transistors (8T)-SRAM cells that enable variability tolerant and low-power SRAM cache designs. Increased sense-amplifier offset voltage due to device mismatch arising from high variability increases delay and power consumption of SRAM design. We have proposed two novel design techniques to reduce offset voltage dependent delays providing a high speed low-power SRAM design. Increasing leakage currents in nano-CMOS technologies pose a major challenge to a low-power reliable design. We have investigated novel segmented supply voltage architecture to reduce leakage power of the SRAM caches since they occupy bulk of the total chip area and power. Future work involves developing leakage reduction methods for the combination logic designs including SRAM peripherals