Clock Gating Cell Circuit for Low-Voltage Edge Stability
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Solution Overview
Problem
Conventional clock gating cells (CGCs) experience functional failures at low voltage operations due to degraded edge rates, leading to premature discharging or charging of internal nodes, which can cause race conditions and power inefficiencies, and existing solutions like over-designing the clock tree or upsizing output logic increase power consumption and area, compromising battery life.
Innovation Solution
The addition of safeguarding circuitry, including additional transistors and inverters in the feedback loop, prevents premature discharging or charging of input nodes during slow-rising or slow-falling clock edges, thereby maintaining node stability and reducing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional CGC architecture is used, then device simplicity is maintained, but functional failures occur at low voltage due to premature discharging of internal nodes
Solution Approach 1:
The patent introduces an intermediate control mechanism (additional transistor controlled by edge detection logic) that mediates between the clock input and the internal node to prevent premature discharging. This intermediary element detects slow edges and blocks the discharging path accordingly, resolving the reliability issue without requiring complete redesign of the CGC architecture.
Solution Approach 2:
The patent applies preliminary anti-action by detecting slow clock edges in advance and preemptively preventing the premature discharging of internal nodes. The edge detection logic identifies problematic transitions before they cause functional failures, and the control mechanism blocks the harmful discharging path before it can affect circuit operation.
2Reliability
If over-designing the clock tree is done to maintain good edge rate, then functional reliability improves, but dynamic power consumption increases
Solution Approach 1:
Instead of globally over-designing the entire clock tree, the patent applies local quality by introducing targeted safeguarding circuitry only at critical CGC locations where slow edges cause problems. This localized approach maintains edge rates where needed while avoiding unnecessary power consumption in other parts of the clock distribution network.
Solution Approach 2:
The patent changes the operational parameters of the CGC by dynamically controlling the discharge path based on detected edge characteristics. Rather than statically over-designing for worst-case scenarios, the circuit adapts its behavior based on actual clock edge quality, enabling reliable operation at lower power consumption levels.
3Speed
If upsizing output logic is done to quickly propagate clock signal, then clock propagation speed improves, but area and dynamic power increase
Solution Approach 1:
The patent extracts the speed-critical function from the output logic and relocates it to a dedicated edge detection and control mechanism. By separating the clock propagation function from the output logic upsizing, the circuit achieves fast propagation through the safeguarding circuitry while maintaining standard-sized output logic, thus reducing area and power consumption.
4Speed
If upsizing output logic is done to quickly propagate clock signal, then clock propagation speed improves, but setup time of enable logic increases
Solution Approach 1:
The patent segments the clock propagation path into distinct functional stages: edge detection, control signal generation, and output propagation. This segmentation allows each stage to be optimized independently, enabling fast propagation through the control mechanism without increasing the setup time requirements of the enable logic, as the stages operate in a coordinated sequence.
Data Source
AI summary
A clock gating cell that comprises a latch in communication with an input enable logic and an output logic circuit, wherein the latch includes a pull-up and/or a pull-down circuit at an input node of the output logic circuit and circuitry preventing premature charge or discharge of the output logic circuit input node by the pull-up and/or the pull-down circuit when the clock gating cell is enabled.