Clock gating

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

Design of a 10GHz clock distribution network using coupled standing-wave oscillators

Abstract: In this paper, a global clock network that incorporates standing waves and coupled oscillators to distribute a high-frequency clock signal with low skew and low jitter is described. The key design issues involved in generating standing waves on a chip are discussed, including minimizing wire loss within an available technology. A standing-wave oscillator, a distributed oscillator that sustains ideal standing waves on lossy wires, is introduced. A clock grid architecture comprised of coupled, standing-wave oscillators and differential, low-swing clock buffers is presented. The measured results for a prototyped standing-wave clock grid operating at 10GHz and fabricated in a 0.18/spl mu/m 6M CMOS logic process are presented. A technique is proposed for on-chip skew measurements with subpicosecond precision.

Power and slew-aware clock network design for through-silicon-via (TSV) based 3D ICs

Abstract: In this paper, three effective design techniques are presented to effectively reduce the clock power consumption and slew of the 3D clock distribution network: (1) controlling the bound of through-silicon-vias (TSVs) used in between adjacent dies, (2) controlling the maximum load capacitance of the clock buffer, (3) adjusting the clock source location in the 3D stack. We discuss how these design factors affect the overall wirelength, clock power, slew, skew, and routing congestion in the practical 3D clock network design. SPICE simulation indicates that: (1) a 3D clock tree with multiple TSVs achieves up to 31% power saving, 52% wirelength saving and better slew control as compared with the single-TSV case; (2) by placing the clock source on the middle die in the 3D stack, an additional 7.7% power savings, 9.2% wirelength savings, and 33% TSV savings are obtained compared with the clock source on the topmost die. This work aims at helping designers construct reliable low-power and low-slew 3D clock network by making the right decisions on TSV usage, clock buffer insertion, and clock source placement.

Power-Driven Flip-Flop Merging and Relocation

Abstract: We propose a power-driven flip-flop (FF) merging and relocation approach that can be applied after conventional timing-driven placement and before clock network synthesis. It targets to reduce the clock network size and thus the clock power consumption while controlling the switching power of the nets connected to the FFs by selectively merging FFs into multibit FFs and relocating them under timing and placement density constraints. The experimental results are very encouraging. For a set of benchmarks, our approach reduced the switching capacitance of clock network by 36%-43% after gated clock tree synthesis. Finally, the total switching capacitance of clock network and nets connected to the FFs is reduced by 24%-29%.

Semiconductor integrated circuit having a clock recovery circuit

Abstract: A clock recovery circuit is provided for use in a memory with a clock synchronized interface, wherein an external clock is temporarily intercepted to shorten lock-in time when an internal clock is to be generated from the external clock. The clock recovery circuit includes a delay circuit array, receiving the external clock, for generating reference clocks, a control circuit comparing phases of the external clock and of the reference clocks and detecting the number of delay stages required for locking in, and a latching circuit for holding the number of delay stages required for locking in. Once synchronism is detected, the generation of internal clock can be resumed in a short period of time even if the supply of the external clock is temporarily suspended.

Clock distribution in a circuit emulator

Abstract: Before using a netlist description of an integrated circuit as a basis for programming a circuit emulator, a clock analysis tool analyzes the netlist to identify synchronizing circuits including clocked devices (“clock sinks”) such a flip-flops, registers and latches for synchronizing communication between blocks of logic within the IC. The tool initially classifies the clock signal input to each clock sink according to its clock domain, sub-domain and phase. The tool then classifies each synchronizing circuit according to relationships between the classifications of the clock signals it employs to clock its input and output clock sinks. The tool then determines, based on the classification of each synchronizing circuit, whether the emulator can reliably emulate that synchronizing circuit, or whether the tool should automatically modify the netlist description of the synchronizing circuit so that the emulator can emulate it. The tool also generates a warning when an emulator may not reliably emulate a synchronizing circuit and the tool cannot automatically modify it so that the emulator can reliably emulate it.