Clock Duty Compensation Gate for Balanced Edge Delays
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Solution Overview
Problem
Existing global signal distribution schemes in large scale integration (LSI) suffer from signal duty degradation due to circuit asymmetry when employing two-input gates, particularly in clock-gating and clock-switching applications, leading to unbalanced delay and slew issues that are not effectively addressed by current active duty tuning strategies.
Innovation Solution
The insertion of duty compensation gates in the clock distribution line, structurally similar to function block gates, balances rise-to-fall and fall-to-rise delays by delaying the earlier edge of the clock signal to compensate for unbalanced delays caused by two-input gates, ensuring equal duty ratio across the circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If two-input gates are used for clock-gating or clock-switching, then power consumption is reduced and clock switching is enabled, but signal duty degrades due to circuit asymmetry
Solution Approach 1:
A duty compensation gate is introduced as an intermediary component between the two-input gate and the clock distribution network. This compensation gate specifically addresses the duty degradation caused by the asymmetric two-input gate, allowing the system to maintain both power efficiency and signal integrity.
Solution Approach 2:
The invention changes the parameters of the clock signal by introducing variable delay paths in the compensation gate. By dynamically adjusting the delay applied to different edges of the clock signal, the system compensates for the asymmetric duty degradation while maintaining the power-saving benefits of two-input gates.
2Manufacturing precision
If active duty tuning strategies such as clock doubling and dividing are applied, then signal duty is maintained, but area penalties and power consumption increase
Solution Approach 1:
The invention extracts only the essential duty compensation function from complex active tuning strategies. Instead of implementing full clock doubling and dividing circuits, the patent isolates and compensates for the specific duty degradation caused by two-input gates, achieving the necessary precision with minimal additional area and power.
Solution Approach 2:
Rather than applying global duty tuning across the entire clock distribution network, the invention applies localized compensation only at points where two-input gates are used. This targeted approach maintains signal duty where needed while avoiding the area and power penalties of system-wide active tuning strategies.
3Device complexity
If two-input gates are used for clock distribution, then device complexity is reduced, but delay unbalance occurs between rise-to-fall and fall-to-rise transitions
Solution Approach 1:
The invention intentionally introduces asymmetric delay paths within the duty compensation gate to counterbalance the inherent asymmetry of two-input gates. By designing the compensation gate with unequal delay elements for different signal transitions, the system achieves symmetric overall delay performance while maintaining the simplicity of two-input gate structures.
Data Source
AI summary
A global clock signal distribution system includes a distribution line that includes gates for signal distribution, a function block gate with at least two input ports and a duty compensation gate with at least two input ports. The duty compensation gate is inserted in the distribution line following the function block gate for balancing rise-to-fall delay and fall-to-rise delay. The duty compensation gate delays an earlier arrived edge of the clock signal more than a later arrived edge of the clock signal to compensate delay unbalance.