980 research outputs found
Mathematical Estimation of Logical Masking Capability of Majority/Minority Gates Used in Nanoelectronic Circuits
In nanoelectronic circuit synthesis, the majority gate and the inverter form
the basic combinational logic primitives. This paper deduces the mathematical
formulae to estimate the logical masking capability of majority gates, which
are used extensively in nanoelectronic digital circuit synthesis. The
mathematical formulae derived to evaluate the logical masking capability of
majority gates holds well for minority gates, and a comparison with the logical
masking capability of conventional gates such as NOT, AND/NAND, OR/NOR, and
XOR/XNOR is provided. It is inferred from this research work that the logical
masking capability of majority/minority gates is similar to that of XOR/XNOR
gates, and with an increase of fan-in the logical masking capability of
majority/minority gates also increases
Using Fine Grain Approaches for highly reliable Design of FPGA-based Systems in Space
Nowadays using SRAM based FPGAs in space missions is increasingly considered due to their flexibility and reprogrammability. A challenge is the devices sensitivity to radiation effects that increased with modern architectures due to smaller CMOS structures. This work proposes fault tolerance methodologies, that are based on a fine grain view to modern reconfigurable architectures. The focus is on SEU mitigation challenges in SRAM based FPGAs which can result in crucial situations
Automated Synthesis of SEU Tolerant Architectures from OO Descriptions
SEU faults are a well-known problem in aerospace environment but recently their relevance grew up also at ground level in commodity applications coupled, in this frame, with strong economic constraints in terms of costs reduction. On the other hand, latest hardware description languages and synthesis tools allow reducing the boundary between software and hardware domains making the high-level descriptions of hardware components very similar to software programs. Moving from these considerations, the present paper analyses the possibility of reusing Software Implemented Hardware Fault Tolerance (SIHFT) techniques, typically exploited in micro-processor based systems, to design SEU tolerant architectures. The main characteristics of SIHFT techniques have been examined as well as how they have to be modified to be compatible with the synthesis flow. A complete environment is provided to automate the design instrumentation using the proposed techniques, and to perform fault injection experiments both at behavioural and gate level. Preliminary results presented in this paper show the effectiveness of the approach in terms of reliability improvement and reduced design effort
A Radiation-Hardened CMOS Full-Adder Based on Layout Selective Transistor Duplication
Single event transients (SETs) have become increasingly problematic for modern CMOS circuits due to the continuous scaling
of feature sizes and higher operating frequencies. Especially when involving safety-critical or radiation-exposed applications, the circuits
must be designed using hardening techniques. In this brief, we present a new radiation-hardened-by-design full-adder cell on 45-nm technology.
The proposed design is hardened against transient errors by selective duplication of sensitive transistors based on a comprehensive radiationsensitivity analysis. Experimental results show a 62% reduction in the SET sensitivity of the proposed design with respect to the unhardened one. Moreover, the proposed hardening technique leads to improvement in performance and power overhead and zero area overhead with respect to the state-of-the-art techniques applied to the unhardened full-adder cell
Radiation tolerant combinational logic cell
A system has a reduced sensitivity to Single Event Upset and/or Single Event Transient(s) compared to traditional logic devices. In a particular embodiment, the system includes an input, a logic block, a bias stage, a state machine, and an output. The logic block is coupled to the input. The logic block is for implementing a logic function, receiving a data set via the input, and generating a result f by applying the data set to the logic function. The bias stage is coupled to the logic block. The bias stage is for receiving the result from the logic block and presenting it to the state machine. The state machine is coupled to the bias stage. The state machine is for receiving, via the bias stage, the result generated by the logic block. The state machine is configured to retain a state value for the system. The state value is typically based on the result generated by the logic block. The output is coupled to the state machine. The output is for providing the value stored by the state machine. Some embodiments of the invention produce dual rail outputs Q and Q'. The logic block typically contains combinational logic and is similar, in size and transistor configuration, to a conventional CMOS combinational logic design. However, only a very small portion of the circuits of these embodiments, is sensitive to Single Event Upset and/or Single Event Transients
Analysis and Design of Resilient VLSI Circuits
The reliable operation of Integrated Circuits (ICs) has become increasingly difficult to
achieve in the deep sub-micron (DSM) era. With continuously decreasing device feature
sizes, combined with lower supply voltages and higher operating frequencies, the noise
immunity of VLSI circuits is decreasing alarmingly. Thus, VLSI circuits are becoming
more vulnerable to noise effects such as crosstalk, power supply variations and radiation-induced
soft errors. Among these noise sources, soft errors (or error caused by radiation
particle strikes) have become an increasingly troublesome issue for memory arrays as well
as combinational logic circuits. Also, in the DSM era, process variations are increasing
at an alarming rate, making it more difficult to design reliable VLSI circuits. Hence, it
is important to efficiently design robust VLSI circuits that are resilient to radiation particle
strikes and process variations. The work presented in this dissertation presents several
analysis and design techniques with the goal of realizing VLSI circuits which are tolerant
to radiation particle strikes and process variations.
This dissertation consists of two parts. The first part proposes four analysis and two
design approaches to address radiation particle strikes. The analysis techniques for the
radiation particle strikes include: an approach to analytically determine the pulse width
and the pulse shape of a radiation induced voltage glitch in combinational circuits, a technique
to model the dynamic stability of SRAMs, and a 3D device-level analysis of the
radiation tolerance of voltage scaled circuits. Experimental results demonstrate that the proposed techniques for analyzing radiation particle strikes in combinational circuits and
SRAMs are fast and accurate compared to SPICE. Therefore, these analysis approaches
can be easily integrated in a VLSI design flow to analyze the radiation tolerance of such
circuits, and harden them early in the design flow. From 3D device-level analysis of the radiation
tolerance of voltage scaled circuits, several non-intuitive observations are made and
correspondingly, a set of guidelines are proposed, which are important to consider to realize
radiation hardened circuits. Two circuit level hardening approaches are also presented
to harden combinational circuits against a radiation particle strike. These hardening approaches
significantly improve the tolerance of combinational circuits against low and very
high energy radiation particle strikes respectively, with modest area and delay overheads.
The second part of this dissertation addresses process variations. A technique is developed
to perform sensitizable statistical timing analysis of a circuit, and thereby improve the
accuracy of timing analysis under process variations. Experimental results demonstrate that
this technique is able to significantly reduce the pessimism due to two sources of inaccuracy
which plague current statistical static timing analysis (SSTA) tools. Two design approaches
are also proposed to improve the process variation tolerance of combinational circuits and
voltage level shifters (which are used in circuits with multiple interacting power supply
domains), respectively. The variation tolerant design approach for combinational circuits
significantly improves the resilience of these circuits to random process variations, with a
reduction in the worst case delay and low area penalty. The proposed voltage level shifter
is faster, requires lower dynamic power and area, has lower leakage currents, and is more
tolerant to process variations, compared to the best known previous approach.
In summary, this dissertation presents several analysis and design techniques which
significantly augment the existing work in the area of resilient VLSI circuit design
Self-healing concepts involving fine-grained redundancy for electronic systems
The start of the digital revolution came through the metal-oxide-semiconductor field-effect transistor (MOSFET) in 1959 followed by massive integration onto a silicon die by means of constant down scaling of individual components. Digital systems for certain applications require fault-tolerance against faults caused by temporary or permanent influence. The most widely used technique is triple module redundancy (TMR) in conjunction with a majority voter, which is regarded as a passive fault mitigation strategy. Design by functional resilience has been applied to circuit structures for increased fault-tolerance and towards self-diagnostic triggered self-healing. The focus of this thesis is therefore to develop new design strategies for fault detection and mitigation within transistor, gate and cell design levels.
The research described in this thesis makes three contributions. The first contribution is based on adding fine-grained transistor level redundancy to logic gates in order to accomplish stuck-at fault-tolerance. The objective is to realise maximum fault-masking for a logic gate with minimal added redundant transistors. In the case of non-maskable stuck-at faults, the gate structure generates an intrinsic indication signal that is suitable for autonomous self-healing functions. As a result, logic circuitry utilising this design is now able to differentiate between gate faults and faults occurring in inter-gate connections. This distinction between fault-types can then be used for triggering selective self-healing responses.
The second contribution is a logic matrix element which applies the three core redundancy concepts of spatial- temporal- and data-redundancy. This logic structure is composed of quad-modular redundant structures and is capable of selective fault-masking and localisation depending of fault-type at the cell level, which is referred to as a spatiotemporal quadded logic cell (QLC) structure. This QLC structure has the capability of cellular self-healing. Through the combination of fault-tolerant and masking logic features the QLC is designed with a fault-behaviour that is equal to existing quadded logic designs using only 33.3% of the equivalent transistor resources. The inherent self-diagnosing feature of QLC is capable of identifying individual faulty cells and can trigger self-healing features.
The final contribution is focused on the conversion of finite state machines (FSM) into memory to achieve better state transition timing, minimal memory utilisation and fault protection compared to common FSM designs. A novel implementation based on content-addressable type memory (CAM) is used to achieve this. The FSM is further enhanced by creating the design out of logic gates of the first contribution by achieving stuck-at fault resilience. Applying cross-data parity checking, the FSM becomes equipped with single bit fault detection and correction
Evaluating Architectural, Redundancy, and Implementation Strategies for Radiation Hardening of FinFET Integrated Circuits
In this article, authors explore radiation hardening techniques through the design of a test chip implemented in 16-nm FinFET technology, along with architectural and redundancy design space exploration of its modules. Nine variants of matrix multiplication were taped out and irradiated with neutrons. The results obtained from the neutron campaign revealed that the radiation-hardened variants present superior resiliency when either local or global triple modular redundancy (TMR) schemes are employed. Furthermore, simulation-based fault injection was utilized to validate the measurements and to explore the effects of different implementation strategies on failure rates. We further show that the interplay between these different implementation strategies is not trivial to capture and that synthesis optimizations can effectively break assumptions about the effectiveness of redundancy schemes
- âŠ