Timing constraints for high speed counterflow-clocked pipelining

technical reportWith the escalation of clock frequencies and the increasing ratio of wire- to gate-delays, clock skew is a major problem to be overcome in tomorrow's high-speed VLSI chips. Also, with an increasing number of stages switching simultaneously comes the problem of higher peak power consumption. In our past work, we have proposed a novel scheme called Counterflow-Clocked (C2) Pipelining to combat these problem, and discussed methods for composing C2 pipelined stages. In this paper, we analyze, in great detail, the timing constraints to be obeyed in designing basic C2 pipelined stages as well as in composing C2 pipelined stages. C2 pipelining is well suited for systems that exhibit mostly uni-directional data flows as well as possess mostly nearest-neighbor connections. We illustrate C2 pipelining on such a design with several design examples. C2 pipelining eases the distribution of high speed clocks, shortens the clock period by eliminating global clock signals, allows natural use of level-sensitive dynamic latches, and generates less internal switching noise due to the uniformly distributed latch operation. By applying C2 pipelining and its composition methods to build a system, VLSI designers can substitute the global clock skew problem with many local one-sided delay constraints

A fast parallel squarer based on divide-and-conquer

Journal ArticleFast and small squarers are needed in many applications such as image compression. A new family of high performance parallel squarers based on the divide-and-conquer method is reported. Our main result was realizing the basis cases of the divide-and-conquer recursion by using optimized n-bit primitive squarers, where n is in the range of 2 to 6. This method reduced the gate count and provided shorter critical paths. A chip implementing an 8-bit squarer was designed, fabricated and successfully tested, resulting in 24 MOPS using a 2-p CMOS fabrication technology. This squarer had two additional features: increased number of squaring operations per unit circuit area, and the potential for reduced power consumption per squaring operation

Automatic rapid prototyping of semi-custom VLSI circuits using FPGAs

Journal ArticleWe describe a technique for translating semi-custom VLSI circuits automatically, integrating two design environments, into field programmable gate arrays (FPGAs) for rapid and inexpensive prototyping. The VLSI circuits are designed using a cell-matrix based environment that produces chips with density comparable to full custom VLSI design. These circuits are translated automatically into FPGAs for testing and system development. A four-bit pipelined array multiplier is used as an example of this translation. The multiplier is implemented in CMOS in both synchronous and asynchronous pipelined versions, and translated into Actel FPGAs both automatically, and by hand for comparison. The six test chips were all found to be fully functional, and the translation efficiency in terms of chip speed and area is shown. This result demonstrates the potential of this approach to system development

Nonselective Blocking of the Sympathetic Nervous System Decreases Detrusor Overactivity in Spontaneously Hypertensive Rats

The involuntary dual control systems of the autonomic nervous system (ANS) in the bladder of awake spontaneously hypertensive rats (SHRs) were investigated through simultaneous registrations of intravesical and intraabdominal pressures to observe detrusor overactivity (DO) objectively as a core symptom of an overactive bladder. SHRs (n = 6) showed the features of overactive bladder syndrome during urodynamic study, especially DO during the filling phase. After injection of the nonselective sympathetic blocking agent labetalol, DO disappeared in 3 of 6 SHRs (50%). DO frequency decreased from 0.98 ± 0.22 min−1 to 0.28 ± 0.19 min−1 (p < 0.01), and DO pressure decreased from 3.82 ± 0.57 cm H2O to 1.90 ± 0.86 cm H2O (p < 0.05). This suggests that the DO originating from the overactive parasympathetic nervous system is attenuated by the nonselective blocking of the sympathetic nervous system. The detailed mechanism behind this result is still not known, but parasympathetic overactivity seems to require overactive sympathetic nervous system activity in a kind of balance between these two systems. These findings are consistent with recent clinical findings suggesting that patients with idiopathic overactive bladder may have ANS dysfunction, particularly a sympathetic dysfunction. The search for newer and better drugs than the current anticholinergic drugs as the mainstay for overactive bladder will be fueled by our research on these sympathetic mechanisms. Further studies of this principle are required

SPS1 deficiency-triggered PGRP-LC and Toll expression controls innate immunity in Drosophila S2 cells

© 2022. Published by The Company of Biologists Ltd.Selenophosphate synthetase 1 (SPS1) is an essential gene for the cell growth and embryogenesis in Drosophila melanogaster. We have previously reported that SPS1 deficiency stimulates the expression of genes responsible for the innate immune system, including antimicrobial peptides (AMPs), in Drosophila S2 cells. However, the underlying mechanism has not been elucidated. Here, we investigated the immune pathways that control the SPS1-deficiency-induced expression of AMPs in S2 cells. It was found that the activation of AMP expression is regulated by both immune deficiency (IMD) and the Toll pathway. Double knockdown of the upstream genes of each pathway with SPS1 showed that the peptidoglycan recognition protein-LC (PGRP-LC) and Toll genes are targeted by SPS1 for regulating these pathways. We also found that the IMD and Toll pathway regulate AMP expression by cross-talking. The levels of PGRP-LC and Toll mRNAs were upregulated upon Sps1 knockdown (6.4±0.36 and 3.2±0.45-fold, respectively, n=3). Overexpression of each protein also upregulated AMPs. Interestingly, PGRP-LC overexpression upregulated AMP more than Toll overexpression. These data strongly suggest that SPS1 controls the innate immune system of D. melanogaster through regulating PGRP-LC and Toll expression.N