GPIO Multiplexing and Level Shifting for Multi-Voltage I/O Buffers
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Solution Overview
Problem
As semiconductor integrated circuits shrink in size, there is a need to reduce the area occupied by general purpose input/output (GPIO) modules while maintaining or improving performance, as existing GPIO modules do not efficiently manage the communication of input/output signals across different voltage domains.
Innovation Solution
The semiconductor integrated circuit incorporates a GPIO module with multiplexing and level shifting circuits that selectively output and convert input/output signals, allowing at least two functional blocks to operate in a mutually exclusive manner based on a common input signal, thereby reducing the number of level shifting circuits and optimizing layout design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple GPIO modules are provided for different voltage domains, then signal communication capability is improved, but the area occupied by GPIO modules increases
Solution Approach 1:
The patent implements a universal GPIO module that can operate in multiple voltage domains (1.2V and 3.3V) by incorporating multiplexing circuits that selectively connect different functional blocks (transmission block, reception block, pull-up/pull-down block) based on the voltage domain. This single module replaces what would traditionally require separate dedicated modules for each voltage domain, thereby reducing area while maintaining full signal communication capability across different voltage levels.
Solution Approach 2:
The patent combines multiple functional blocks (transmission, reception, pull-up, pull-down) and multiple voltage domain support into a single integrated GPIO module. By merging these functions and using multiplexing to share resources across voltage domains, the design eliminates the need for separate GPIO modules for each voltage domain, thus reducing the total area occupied while preserving all communication capabilities.
2Manufacturing precision
If separate level shifting circuits are provided for each functional block, then voltage level conversion accuracy is improved, but the area occupied by level shifting circuits increases
Solution Approach 1:
The patent merges multiple level shifting circuits into a shared resource by placing them in the common signal path and using multiplexing to selectively activate the appropriate level shifting circuit based on the operating voltage domain. This allows a single set of level shifting circuits to serve multiple functional blocks and voltage domains, reducing area while maintaining voltage level conversion accuracy through dedicated level shifting paths when activated.
Solution Approach 2:
The patent implements dynamic control of level shifting circuits through multiplexing, where the activation and deactivation of specific level shifting circuits is controlled by control signals based on the current voltage domain and operational mode. This dynamic switching allows the system to use only the necessary level shifting circuits at any given time, optimizing area utilization while ensuring accurate voltage level conversion is available when needed.
Data Source
AI summary
An input/output module includes a multiplexing circuit, which is responsive to a plurality of I/O signals and configured to output a selected one of the plurality of I/O signals according to a value of a common input signal received at a control terminal thereof. A level shifting circuit is provided, which is configured to convert a voltage level of the selected one of the plurality of I/O signals and a voltage level of the common input signal. At least two functional blocks are provided, which are each configured to receive the selected one of the plurality of I/O signals having the converted voltage level, yet operate in a mutually exclusive manner according to a value of the common input signal having the converted voltage level.