Compact Clock-Gating Cell Topology for Low Power and Setup Time

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Solution Overview

Problem

Existing clock-gating cells face challenges in achieving low area, low power consumption, and low setup time, which are essential for reducing dynamic power dissipation in integrated circuits while ensuring efficient clock management.

Innovation Solution

A clock-gating cell design incorporating an enable module and a latch module with pMOS transistors, where the latch module enables and disables the clock based on the enable module input, utilizing a NOR gate and pMOS transistors to minimize area and power consumption, and optimize setup times.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of stationary object

If traditional clock-gating cell designs are used, then clock gating functionality is achieved, but area consumption increases and power dissipation increases

Engineering Contradiction:
ImproveareaVSAvoidclock gating functionality
Core Design Contradiction:
Area of stationary objectVSReliability

Solution Approach 1:

The patent extracts and removes unnecessary transistors from the traditional clock-gating cell architecture. By taking out redundant components while retaining the essential clock gating functionality through the optimized latch circuit with pMOS transistors, the design achieves reduced area consumption without sacrificing the core clock gating capability.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent merges the enable logic and latch functionality into a compact integrated structure. By combining these functions into a unified circuit design with shared components and optimized transistor arrangements, the overall area is reduced while maintaining complete clock gating functionality.

Inventive Principle:
Principle #5Merging (Combining)

2Use of energy by stationary object

If traditional clock-gating cell designs are used, then clock gating functionality is achieved, but power consumption increases

Engineering Contradiction:
Improvepower consumptionVSAvoidclock gating functionality
Core Design Contradiction:
Use of energy by stationary objectVSReliability

Solution Approach 1:

The patent removes unnecessary transistors and circuit paths that contribute to dynamic power consumption. By extracting redundant components and simplifying the circuit topology, the design reduces the number of switching events and associated power dissipation while preserving essential clock gating functionality.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent changes the transistor type parameter from mixed nMOS/pMOS to predominantly pMOS in the latch circuit. This parameter change exploits the higher input impedance and lower leakage characteristics of pMOS transistors, thereby reducing static and dynamic power consumption while maintaining functional reliability.

Inventive Principle:
Principle #35Parameter changes

3Area of stationary object

If clock-gating cell area is reduced, then area savings are achieved, but setup time may increase

Engineering Contradiction:
ImproveareaVSAvoidsetup time
Core Design Contradiction:
Area of stationary objectVSLoss of time

Solution Approach 1:

The patent applies local quality optimization by using pMOS transistors with specifically optimized dimensions and characteristics in critical path locations. This local optimization ensures adequate drive strength and timing performance in the latch circuit while allowing area reduction in non-critical areas of the clock-gating cell.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent employs a composite transistor design approach, combining pMOS transistors with optimized sizing ratios and threshold voltages to achieve both compact area and fast switching characteristics. The composite structure balances area efficiency with timing performance requirements.

Inventive Principle:
Principle #40Composite materials

Data Source

PatentEP3245735B1Clock-gating cell with low area, low power, and low setup time
Publication Date: 2020.08.05 QUALCOMM INC
  • EP3245735B1 patent drawingFigure 1
  • EP3245735B1 patent drawingFigure 2
  • EP3245735B1 patent drawingFigure 3

AI summary

A CGC includes an enable module (302) and a latch module (306). The enable module (302) has an enable module input and an enable module output. The latch module (306) has latch module inputs and a latch module output. The latch module inputs include a latch module clock input for receiving a clock and a latch module enable input for receiving the enable module output. The latch module enable input is coupled to the enable module output. The latch module (306) is configured to enable and to disable the clock (clk_in) via the latch module output based on the enable module input. The latch module (306) includes an internal enable node that is the latch module output. The latch module is configured to cause the internal enable node to transition from low to high as a function of the enable module output, the internal enable node and the clock.