Clock Doubler Circuit for BTI-Resistant High-Frequency Clock Trees
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Solution Overview
Problem
Memory systems face challenges in maintaining high-frequency clock signals due to bias temperature instability (BTI) degradation, which affects the performance and lifespan of transistors, especially in systems with long clock trees, leading to increased latency and reduced bandwidth.
Innovation Solution
A clock doubler circuit is implemented to generate a higher frequency clock signal by combining two lower frequency clock signals with opposite phases, reducing the length of the clock tree traversed by the high-frequency signal and mitigating BTI degradation, while a duty cycle monitor adjusts the phases to ensure an optimal duty cycle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If high-frequency clock signals are used, then processing speed and bandwidth are improved, but BTI degradation increases
Solution Approach 1:
The clock tree is segmented into multiple sections with clock doubler circuits inserted at strategic points. This divides the long clock tree into shorter segments, allowing high-frequency operation in localized regions while maintaining overall system reliability and reducing cumulative BTI degradation across the entire clock distribution network.
Solution Approach 2:
The patent introduces clock doubling in the frequency dimension, transforming the clock signal frequency locally within the clock tree. By inserting clock doubler circuits that generate doubled-frequency clocks from lower-frequency parent clocks, the system achieves high-speed processing in specific regions without subjecting the entire clock tree to high-frequency stress that causes BTI degradation.
2Productivity
If clock frequency is increased, then bandwidth is improved, but transistor lifespan is reduced
Solution Approach 1:
Different regions of the clock tree are assigned different clock frequencies based on their specific performance requirements. Clock doubler circuits are strategically placed in regions where high bandwidth is critical, while other regions continue to operate at lower frequencies. This local differentiation allows the system to achieve high bandwidth where needed without unnecessarily exposing all transistors to high-frequency stress that reduces lifespan.
3Device complexity
If long clock trees are used, then system complexity is reduced, but BTI degradation increases
Solution Approach 1:
The long clock tree is divided into multiple shorter segments by inserting clock doubler circuits at intermediate points. Each segment operates independently at appropriate frequencies, reducing the cumulative BTI degradation that would occur in a single long high-frequency clock path, while maintaining overall system functionality without requiring complete redesign.
Data Source
AI summary
Methods, systems, and devices for techniques for clock doubling are described. A clock adjustment circuit may receive as inputs two clock signals that each have the same frequency and different phases and may generate a clock signal with a higher frequency than the two clock signal inputs. A duty cycle monitor may monitor and support correction of a shift in the relative phases of the two input clocks to maintain a consistent duty cycle of the generated higher frequency clock signal. The clock adjustment circuit may reduce the length of a clock tree that is traversed by the higher frequency clock, such as to reduce bias temperature instability degradation or other types of signal degradation.