In this paper, we propose a set of rules for consistent estimation of the real performance and power features of the flip-flop and master-slave latch structures. A new simulation and optimization approach is presented, targeting both high-performance and power budget issues. The analysis approach reveals the sources of performance and power-consumption bottlenecks in different design styles. Certain misleading parameters have been properly modified and weighted to reflect the real properties of the compared structures. Furthermore, the results of the comparison of representative master-slave latches and flip-flops illustrate the advantages of our approach and the suitability of different design styles for high-performance and low-power applications.

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Comparative analysis of master-slave latches and flip-flops for high-performance and low-power systems

Clock distribution networks synchronize the flow of data signals among synchronous data paths. The design of these networks can dramatically affect system-wide performance and reliability. A theoretical background of clock skew is provided in order to better understand how clock distribution networks interact with data paths. Minimum and maximum timing constraints are developed from the relative timing between the localized clock skew and the data paths. These constraint relationships are reviewed, and compensating design techniques are discussed. The field of clock distribution network design and analysis can be grouped into a number of subtopics: 1) circuit and layout techniques for structured custom digital integrated circuits; 2) the automated layout and synthesis of clock distribution networks with application to automated placement and routing of gate arrays, standard cells and larger block-oriented circuits; 3) the analysis and modeling of the timing characteristics of clock distribution networks; and 4) the scheduling of the optimal timing characteristics of clock distribution networks based on architectural and functional performance requirements. Each of these areas is described the clock distribution networks of specific industrial circuits are surveyed and future trends are discussed.

Clock distribution networks in synchronous digital integrated circuits

Power consumption from logic circuits, interconnections, clock distribution, on chip memories, and off chip driving in CMOS VLSI is estimated. Estimation methods are demonstrated and verified. An estimate tool is created. Power consumption distribution between interconnections, clock distribution, logic gates, memories, and off chip driving are analyzed by examples. Comparisons are done between cell library, gate array, and full custom design. Also comparisons between static and dynamic logic are given. Results show that the power consumption of all interconnections and off chip driving can be up to 20% and 65% of the total power consumption respectively. Compared to cell library design, gate array designed chips consume about 10% more power, and power reduction in full custom designed chips could be 15%. >

Power consumption estimation in CMOS VLSI chips

Design and experimental evaluation of a new sense-amplifier-based flip-flop (SAFF) is presented. It was found that the main speed bottleneck of existing SAFF's is the cross-coupled set-reset (SR) latch in the output stage. The new flip-flop uses a new output stage latch topology that significantly reduces delay and improves driving capability. The performance of this flip-flop is verified by measurements on a test chip implemented in 0.18 /spl mu/m effective channel length CMOS. Demonstrated speed places it among the fastest flip-flops used in the state-of-the-art processors. Measurement techniques employed in this work as well as the measurement set-up are discussed in this paper.

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Improved sense-amplifier-based flip-flop: design and measurements

A high-speed VLSI multiplication algorithm internally using redundant binary representation is proposed. In n bit binary integer multiplication, n partial products are first generated and then added up pairwise by means of a binary tree of redundant binary adders. Since parallel addition of two n-digit redundant binary numbers can be performed in a constant time independent of n without carry propagation, n bit multiplication can be performed in a time proportional to log2 n. The computation time is almost the same as that by a multiplier with a Wallace tree, in which three partial products will be converted into two, in contrast to our two-to-one conversion, and is much shorter than that by an array multiplier for longer operands. The number of computation elements of an n bit multiplier based on the algorithm is proportional to n2. It is almost the same as those of conventional ones. Furthermore, since the multiplier has a regular cellular array structure similar to an array multiplier, it is suitable for VLSI implementation. Thus, the multiplier is excellent in both computation speed and regularity in layout. It can be implemented on a VLSI chip with an area proportional to n2 log2 n. The algorithm can be directly applied to both unsigned and 2's complement binary integer multiplication.

High-Speed VLSI Multiplication Algorithm with a Redundant Binary Addition Tree

A key element (one is tempted to say the heart) of most digital systems is the clock. Its period determines the rate at which data are processed, and so should be made as small as possible, consistent with reliable operation.

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Clocking Schemes for High-Speed Digital Systems

It is shown how any combinational function that can be described by a flow table—or equivalently—is realizable in iterative form—can be realized in tree form. The propagation delay is then proportional to the logarithm of n, the number of inputs, while the logic complexity is a linear function of n. These results are related to various implementations of high-speed binary adders and a proposed new high-speed adder circuit.

Tree Realizations of Iterative Circuits

The self-synchronizing (SS) sequential circuits proposed by Chuang and Das, as well as by Rey and Vaucher are analyzed and compared. A variation of the latter system is proposed. It is shown that none of the above approaches can be used for unrestricted input change (UIC) operation. Procedures for synthesizing Huffman type asynchronous circuits suitable for UIC operation are improved. Data handling rates for the SS and Huffman type circuits are compared for SIC and MIC operation.

Unger

Papers

Clocking Schemes for High-Speed Digital Systems

Tree Realizations of Iterative Circuits

Self-Synchronizing Circuits and Nonfundamental Mode Operation