Fault modeling and analysis of short defects in CMOS based reversible circuits

This paper presents a SPICE based analysis of reversible circuits affected by the short defects: the gate oxide defect and the source-drain defect. The simulations are performed using realistic transistor models (the BSIM4 model) and take into account the resistive nature of the gate oxide and the source drain shorts. We aim at determining dependence between the short's resistance and the output voltage. Furthermore, we analyze the timing characteristics of reversible circuits affected by such faults. The goal is to develop logic and delay fault models for CMOS based reversible gates. This way, Boolean test strategies and logic level fault tolerant mechanisms and strategies can be devised for reversible circuits

FPGA implementations of low precision floating point multiply-accumulate

Floating point (FP) multiply-accumulate (MAC) represents one of the most important operations in a wide range of applications, such as DSP, multimedia or graphic processing. This paper presents a FP MAC half precision (16-bit) FPGA implementation. The main contribution of this work is represented by the utilization of modern FPGA DSP block for performing both mantissa multiplication and mantissa accumulation. In order to use the DSP block for these operations, the alignment right shifts are performed before the multiply-add stage: a right shift on one of the multiplicand, and, a left shift for the other. This results in efficient DSP usage; thus both cost savings and higher performance (high working frequencies and low latencies) are targeted for MAC operations

Multi-Level Simulated Fault Injection for Data Dependent Reliability Analysis of RTL Circuit Descriptions

This paper proposes data-dependent reliability evaluation methodology for digital systems described at Register Transfer Level (RTL). It uses a hybrid hierarchical approach, combining the accuracy provided by Gate Level (GL) Simulated Fault Injection (SFI) and the low simulation overhead required by RTL fault injection. The methodology comprises the following steps: the correct simulation of the RTL system, according to a set of input vectors, hierarchical decomposition of the system into basic RTL blocks, logic synthesis of basic RTL blocks, data-dependent SFI for the GL netlists, and RTL SFI. The proposed methodology has been validated in terms of accuracy on a medium sized circuit – the parallel comparator used in Check Node Unit (CNU) of the Low-Density Parity-Check (LDPC) decoders. The methodology has been applied for the reliability analysis of a 128-bit Advanced Encryption Standard (AES) crypto-core, for which the GL simulation was prohibitive in terms of required computational resources

Check node unit for LDPC decoders based on one-hot data representation of messages

International audienc

Non-surjective finite alphabet iterative decoders

International audienceThis paper introduces a new theoretical framework, akin to the use of imprecise message storage in Low Density Parity Check (LDPC) decoders, which is seen as an enabler for cost-effective hardware designs. The proposed framework is the one of Non-Surjective Finite Alphabet Iterative Decoders (NS-FAIDs), and it is shown to provide a unified approach for several designs previously proposed in the literature. NS-FAIDs are optimized by density evolution for WiMAX irregular LDPC codes and we show they provide different trade-offs between hardware complexity and decoding performance. In particular, we derive a set of 27 NS-FAIDs that provide decoding gains up to 0.36 dB, while yielding a memory / interconnect reduction up to 25% / 30% compared to the Min-Sum decoder