Clock gating

About: Clock gating is a research topic. Over the lifetime, 7838 publications have been published within this topic receiving 107903 citations.

Clock-gating and its application to low power design of sequential circuits

Abstract: This paper models the clock behavior in a sequential circuit by a quaternary variable and uses this representation to propose and analyze two clock-gating techniques. It then uses the covering relationship between the triggering transition of the clock and the active cycles of various flip flops to generate a derived clock for each flip flop in the circuit. A technique for clock gating is also presented, which generates a derived clock synchronous with the master clock. Design examples using gated clocks are provided next. Experimental results show that these designs have ideal logic functionality with lower power dissipation compared to traditional designs.

A true single-phase-clock dynamic CMOS circuit technique

Abstract: The authors describe two dynamic circuit techniques, using only a single-phase clock which is never inverted. This class of circuits has the advantages of simple clock distribution, small area for clock lines reduced clock skew problems, and high speed. Several examples are demonstrated.

Clock vernier adjustment

Abstract: A integrated circuit, such as a memory integrated circuit, includes a vernier clock adjustment circuit receiving an input clock signal and providing a rising-edge clock signal representing the input clock signal delayed by a rising-edge delay and providing a falling-edge clock signal representing the input clock signal delayed by a falling-edge delay. An edge triggered circuit receives data and the rising-edge and falling-edge clock signals, and stores data at the rising-edge of the rising-edge clock signal and at the falling-edge of the falling-edge clock signal. One form of the invention is a memory system having a memory controller coupled to memory modules through data and command busses. Each memory module includes the vernier clock adjustment circuitry.

Design of PLL-based clock generation circuits

Abstract: The design of clock generation circuitry being used as a part of a high-performance microprocessor chip set is described. A self-calibrating tapped delay line is used to generate four nonoverlapping clock phases of a system clock. A charge-pump phase-locked loop (PLL) calibrates the delay per stage of the delay line. Using this technique, it is possible to obtain an accurate phase relationship between the off-chip reference clock and the internal clock signals. Experimental results show that required timing relations can be obtained with less than 2-ns clock skew for frequencies from 1 to 18 MHz.

Static Timing Analysis for Nanometer Designs: A Practical Approach

Abstract: The book covers topics such as cell timing and power modeling; interconnect modeling and analysis, delay calculation, crosstalk, noise and the chip timing verification using static timing analysis. For each of these topics, the book provides a theoretical background as well as detailed examples to elaborate the concepts. The static timing analysis topics covered start from verification of simple blocks useful for a beginner to this field. The topics then extend to complex nanometer designs with in-depth treatment of concepts such as modeling of on-chip variation, clock gating, half-cycle paths, as well as timing of source-synchronous interfaces such as DDR. The impact of crosstalk on timing and noise is covered as is the usage of hierarchical design methodology. This book addresses CMOS logic gates, cell library, timing arcs, waveform slew, cell capacitance, timing modeling, interconnect parasitics and coupling, pre- and post-layout interconnect modeling, delay calculation, specification of timing constraints for analysis of internal paths as well as IO interfaces. Advanced modeling and analysis concepts such as controlled current source timing and noise models for nanometer technologies, power modeling including active and leakage power, crosstalk timing and crosstalk glitch calculation, verification of half-cycle and multi-cycle paths, false paths, synchronous interfaces are also covered.