Split Logic Clock Buffer Layout for Self-Heating Delay Characterization
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Solution Overview
Problem
Existing integrated circuit (IC) designs face challenges in accurately predicting and managing self-heating and temperature-related reliability issues in logic-clock-buffers (LCBs), which can lead to premature failure due to effects like electromigration, stress migration, and bias temperature degradation.
Innovation Solution
A self-heating LCB characterization circuit is introduced, incorporating split-logic-clock-buffers (split-LCBs) with an integrated inverter circuit and a clock distribution network, allowing for direct analysis of timing effects by establishing a ring oscillator circuit to measure self-heating-induced delays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If LCBs operate with high switching activities to ensure reliable clock signal distribution, then clock signal reliability is improved, but self-heating and temperature rise increase causing timing skew and reliability degradation
Solution Approach 1:
The output drive stage is divided into upstream and downstream portions with a temperature sense circuit region inserted between them. This segmentation allows independent measurement of temperature-induced timing skew without disrupting the overall clock distribution function, enabling characterization of thermal effects while maintaining operational reliability
Solution Approach 2:
A delay sense circuit is introduced as an intermediary element between the upstream and downstream drive portions. This circuit measures the timing skew caused by self-heating without directly participating in the clock signal generation, allowing temperature characterization while preserving the primary clock distribution function
2Productivity
If temperature rise is allowed to occur during LCB operation, then switching performance is maintained, but reliability degradation mechanisms such as electromigration and stress migration are enhanced
Solution Approach 1:
The temperature sense circuit provides feedback information about temperature-induced timing skew to enable characterization of self-heating effects. This feedback mechanism allows monitoring of thermal conditions that affect reliability without requiring active cooling or reduction of switching performance
Solution Approach 2:
The invention characterizes temperature effects by measuring changes in timing parameters (timing skew) rather than directly controlling temperature. By monitoring parameter changes caused by self-heating, the system can quantify thermal impact on reliability while maintaining normal operational parameters
3Measurement precision
If a temperature sense circuit is inserted in the output drive stage to measure timing skew, then self-heating characterization is enabled, but device complexity increases
Solution Approach 1:
The delay sense circuit is designed to serve multiple functions: it characterizes temperature-induced timing skew, validates timing analysis models, and provides data for thermal management decisions. This multi-functionality justifies the added circuit complexity by delivering comprehensive thermal characterization capabilities
Solution Approach 2:
The temperature sense circuit is nested within the existing output drive stage structure, with the delay sense circuit embedded between upstream and downstream portions. This nesting approach integrates the measurement function into the existing architecture rather than adding completely separate external measurement equipment
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enables precise characterization of self-heating loss performance in LCBs, improving timing prediction and reducing the risk of IC failure by quantifying temperature-induced delays and current changes.
Implementation Method 1
When LCBs operate, they consume electrical power through switching activities (e.g., performed by transistors and/or latches), which cause self-heating and temperature rise within the IC
Implementation Method 2
The self-heating and temperature rise may alter the electrical characteristics of the IC components, which can affect the speed at which the signals propagate through the split-LCBs
Data Source
AI summary
A split-logic-clock-buffer (split-LCB) includes an input clock stage configured to receive an input clock signal, an output drive stage configured to output an output clock signal, and a clock distribution network interposed between the input clock stage and the output drive stage. The clock distribution network is configured to route the input clock signal to the drive output stage. The output drive stage includes an temperature sense circuit region that splits the output drive stage into an upstream drive portion and a downstream drive portion.