Clock Gating Cell Layout to Cut Parasitic Clock Power
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Solution Overview
Problem
Clock gating cells consume power even when no clock signal is output, leading to inefficiencies in power management in clock synchronization systems.
Innovation Solution
A clock gating cell design that includes a pair of transistors to receive the clock signal, reducing power consumption by minimizing the number of circuit elements directly receiving the input clock signal, thereby reducing parasitic capacitance and overall power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a conventional clock gating cell uses multiple circuit elements to receive the clock signal, then the clock signal can be properly gated and output, but the power consumption increases due to parasitic capacitance from multiple transistors receiving the clock signal
Solution Approach 1:
The patent extracts the clock signal reception function to only one transistor (the third transistor in the embodiment), separating it from other circuit elements. This minimizes the number of transistors that directly receive the clock signal, thereby reducing parasitic capacitance and power consumption while maintaining the clock gating functionality through the interaction of the first, second, and third transistors with the enable signal and clock signal.
2Use of energy by moving object
If a clock gating cell selectively outputs a clock signal to improve power efficiency, then system power efficiency increases, but the cell still consumes power due to the clock signal even when no clock signal is output
Solution Approach 1:
The patent implements dynamic control of the transistor states based on the enable signal. When the enable signal is inactive, the first and second transistors are configured to prevent the clock signal from propagating through the third transistor, dynamically switching the circuit from a clock-passing state to a clock-blocking state. This dynamic operation reduces power consumption by eliminating unnecessary clock signal transitions at the output while maintaining the ability to selectively gate the clock signal when needed.
Data Source
AI summary
A clock gating cell including: a first circuit configured to receive an enable signal and an inverted output clock signal and generate a first signal through a first node; a second circuit configured to receive the first signal and generate an inverted first signal; a third circuit configured to receive the first signal, the inverted first signal, and an input clock signal, generate the first signal by being connected to the first circuit through the first node, and generate the inverted output clock signal through a second node; and a fourth circuit configured to receive the first signal, generate the inverted output clock signal by being connected to the third circuit through the second node, and generate the output clock signal, wherein the third circuit includes a pair of transistors receiving the input clock signal.