IC I/O Pad Assignment Optimization via Inductance Matrix
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Solution Overview
Problem
Manual assignment of signals to input/output (I/O) pads in programmable logic devices (PLDs) leads to high crosstalk and inefficient utilization of I/O pads, as existing methods rely heavily on location-based guidelines that are not comprehensive in preventing crosstalk contributions.
Innovation Solution
A method that uses an inductance matrix to optimize signal-to-pad assignments by determining differential mutual inductance for each open pad location and assigning single-ended signals to those with the lowest inductance, while updating total jitter to ensure it remains within a budget or meets a target number of assignments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If manual assignment of signals to I/O pads is used, then the design process is simple, but crosstalk increases and pad utilization becomes inefficient
Solution Approach 1:
The patent transforms the pad assignment process from manual to automated optimization by changing the parameter selection criteria. Instead of relying on designer manual selection, the system automatically calculates differential mutual inductance values for all pad pairs and selects assignments that minimize crosstalk parameters, thereby reducing harmful crosstalk effects while maintaining design simplicity through automation.
Solution Approach 2:
The patent replaces the manual mechanical assignment process with an automated computational system. The EDA tool automatically performs inductance matrix calculations, evaluates differential mutual inductance for candidate assignments, and optimizes pad assignments without manual intervention, substituting human manual operations with automated electronic design automation processes.
2Ease of operation
If location-based guidelines are used for pad assignment, then the process is straightforward, but crosstalk prevention is not comprehensive
Solution Approach 1:
The patent changes the basis of assignment from location-based guidelines to parameter-based optimization. Instead of following predetermined location rules, the system calculates actual differential mutual inductance values for each candidate assignment and selects based on minimizing this parameter, providing comprehensive and reliable crosstalk prevention while maintaining straightforward automated execution.
Solution Approach 2:
The patent implements a feedback mechanism where the system calculates differential mutual inductance values, evaluates their impact on crosstalk, and uses this feedback to iteratively optimize pad assignments. The EDA tool continuously refines assignments based on calculated inductance parameters, ensuring reliable crosstalk prevention while maintaining process straightforwardness through automated feedback loops.
3Object-affected harmful factors
If automated optimization using inductance matrix is implemented, then crosstalk is reduced and pad utilization improves, but computational complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing the inductance matrix for all pad pairs before the actual assignment process. This preliminary computation of inductance parameters allows the optimization algorithm to efficiently evaluate candidate assignments without performing complex calculations during the assignment phase, reducing computational complexity while achieving effective crosstalk reduction.
Solution Approach 2:
The patent segments the complex optimization problem into manageable steps: first calculating the inductance matrix, then evaluating differential mutual inductance for candidate assignments, and finally selecting optimal assignments. This segmentation of the computational process reduces overall complexity by breaking down the optimization into discrete, manageable computational tasks that can be executed systematically.
Data Source
AI summary
The present disclosure relates to an innovative method of assigning signals to general-purpose input/output pads of an integrated circuit chip. An inductance matrix for the input/output pads is obtained. A candidate assignment is made of a differential signal to a pair of the input/output pads, and a differential mutual inductance is determined for each open pad location in relation to the pair of input/output pads. Single-ended signals are assigned to open pad locations having the lowest differential mutual inductances. The jitter contribution due to each assigned single-ended signal is computed, and a total jitter is updated. In a first embodiment, said assigning, computing and updating steps are repeated until the total jitter exceeds a total jitter budget. In a second embodiment, said assigning, computing and updating steps are repeated until a number of assigned single-ended signals is equal to a target number. Other embodiments and features are also disclosed.