This paper introduces a new family of low-power and high-performance flip-flops, namely conditional data mapping flip-flops (CDMFFs), which reduce their dynamic power by mapping their inputs to a configuration that eliminates redundant internal transitions. We present two CDMFFs, having differential and single-ended structures, respectively, and compare them to the state-of-the-art flip-flops. The results indicate that both CDMFFs have the best power-delay product in their groups, respectively. In the aspect of power dissipation, the single-ended and differential CDMFFs consume the least power at data activity less than 50%, and are 31% and 26% less power than the conditional capture flip-flops at 25% data activity, respectively. In the aspect of performance, CDMFFs achieve small data-to-output delays, comparable to those of the transmission-gate pulsed latch and the modified-sense-amplifier flip-flop. In the aspect of timing reliability, CDMFFs have the best internal race immunity among pulse-triggered flip-flops. A post-layout case study is demonstrated with comparison to a transmission-gate flip-flop. The results indicate the single-ended CDMFF has 34% less in data-to-output delay and 28% less in power at 25% data activity, in spite of the 34% increase in size

This paper investigates substrate noise influence on circuit performance in a variable threshold-voltage scheme (VT scheme) where threshold voltage is dynamically varied by substrate-bias control to reduce active power dissipation. It is experimentally examined that substrate-bias can be controlled stably with very few substrate-contacts. Measured tracking jitter of a delay-locked loop implemented by interconnections in an 8 mm-square gate array does not degrade even when substrate-contacts are removed except for one at every strip of p-sub and n-well: A 2 mm-square discrete cosine transform core processor with no substrate-contact except in its periphery operates at supply voltages from 1.3 V to above 3 V even though it employs small-swing differential dynamic pass-transistor logic. No performance degradation nor latchup is observed in these chips even when 100 k/spl Omega/ resistance is added to the substrate. These experimental results demonstrate noise immunity of the VT scheme, and indicate the possibility that the VT scheme can be applied to existing macro design easily.

Multiple architecture for symbolic applications (MASA) is a first cut at a processor architecture intended as a building block for a multiprocessor that can execute parallel Lisp programs efficiently. MASA features a tagged architecture, multiple contexts, fast-trap handling, and a synchronization bit in every memory word. MASA's principal novelty is its use of multiple contexts both to support multithreaded execution-interleaved execution from separate instruction streams-and to speed up procedure calls and trap handling in the same manner as register windows. A project is underway to evaluate MASA-like architectures for executing programs written in Multilisp.>