Digital electronics

About: Digital electronics is a research topic. Over the lifetime, 10354 publications have been published within this topic receiving 153532 citations.

Built-in self-test with weighted random pattern hardware

Abstract: The authors address scan-based built-in self-test (BIST) of digital circuits that are highly resistant to testing with uniform random patterns. Introducing a procedure, the precompute test patterns for random-pattern resistant faults and generate optimized distributions of weights that guarantee pattern coverage in a given number of random trials. The software implementation offers a tradeoff in the number of distributions (hardware memory) and the length of the total test time. The hardware implementation is based on a canonic weighting circuit that interfaces to a circulating memory and a pseudo-random source. >

Bisitable digital circuitry

Abstract: Bistable digital circuits including cross coupled gates having complementary inputs provided by CMOS threshold circuits coupled to a common digital signal input. Complementary unbalanced transfer characteristics of the threshold circuits provide widely separated high and threshold voltages approaching respective high and low supply potentials. The coupling between gates maintains the bistable digital circuits in a given stable state until the high and low threshold voltages are crossed over in response to a change in logical level at the signal input.

On evolution of relatively large combinational logic circuits

Abstract: Evolvable hardware (EHW) (Yao and Higuchi, 1999) is a technique introduced to automatically design circuits where the circuit configuration is carried out by evolutionary algorithms. One of the main difficulties in using EHW to solve real-world problems is the scalability. Until now, several strategies have been proposed to avoid this problem, but none of them completely tackle the issue. In this paper three different methods for evolving the most complex circuits have been tested for their scalability. These methods are bi-directional incremental evolution (SO-BIE); generalised disjunction decomposition (GD-BIE) and evolutionary strategies (ES) with dynamic mutation rate. In order to achieve the generalised conclusions the chosen approaches were tested using multipliers, traditionally used in EHW, but also logic circuits taken from MCNC (Yang, 1991) benchmark library and randomly generated circuits. The analysis of the approaches demonstrated that PLA-based ES is capable of evolving logic circuits of up to 12 inputs. The use of SO-BIE allows the generation of fully functional circuits of 14 inputs and GD-BIE is estimated to be able to evolve circuits of 21 inputs.

A single 1.5-V digital chip for a 10/sup 6/ synapse neural network

Abstract: A digital-chip architecture for a 10/sup 6/-synapse neural network is proposed. It runs on a 1.5-V dry cell to allow its use in portable equipment. An on-chip DRAM cell array stores synapse weights digitally to provide easy programmability and automatic refreshing. A pitch-matched interconnection and a combinational unit circuit for summing product allow a tight layout. A dynamic data transfer circuit and the 1.5-V operation of the entire chip reduce the power dissipation, but the parallel processing nonetheless provides high speed at the 1.5-V supply. Estimated power dissipation of 75 mW and a processing speed of 1.37 giga connections per second are predicted for the chip. The memory and the processing circuits can be integrated on a 15.4-mm*18.6-mm chip by using a 0.5- mu m CMOS design rule. A scaled-down version of the chip that has an 8-kb DRAM cell array was fabricated, and its operation was confirmed. >

Constant Delay Logic Style

Abstract: A constant delay (CD) logic style is proposed in this paper, targeting at full-custom high-speed applications. The CD characteristic of this logic style regardless of the logic type makes it suitable in implementing complicated logic expressions such as addition. CD logic exhibits a unique characteristic where the output is pre-evaluated before the inputs from the preceding stage is ready. This feature offers performance advantage over static and dynamic domino logic styles in a single-cycle multistage circuit block. Several design considerations including timing window width adjustment and clock distribution are discussed. Using 65-nm general-purpose CMOS technology, the proposed logic demonstrates an average speedup of 94% and 56% over static and dynamic domino logic, respectively, in five different logic gates. Simulation results of 8-bit ripple carry adders show that CD logic is 39% and 23% faster than the static and dynamic-based adders, respectively. CD logic also demonstrates 39% speedup and 64% (22%) energy-delay product (EDP) reduction from static logic at 100% (10%) data activity in 32-bit carry lookahead adders. For 8-bit Wallace tree multiplier, CD logic achieves a similar speedup with at least 50% EDP reduction across all data activities.