Single-Path I/O Circuit With Selective Termination for Low-Voltage Signals
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Solution Overview
Problem
Existing input/output circuits in semiconductor devices face challenges in minimizing area and reducing capacitance loading while ensuring accurate data transmission and reception, especially with low voltage input data, and require separate paths for input and output operations.
Innovation Solution
The proposed input/output circuit design includes a driving unit with transistors and switch elements configured to perform both input and output operations through a single path, utilizing transistors and switch elements to minimize area and capacitance loading, and incorporates a termination resistor to prevent signal reflection, allowing for efficient data transmission and reception even at low voltage levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate paths are used for input and output operations, then reliability of data transmission is improved, but area occupied by the circuit increases
Solution Approach 1:
The patent merges the input and output paths into a single shared path. The same physical connection is used for both receiving input data from external devices and outputting data to external devices, eliminating the need for separate input and output paths. This reduces the overall circuit area while maintaining functional separation through control signals that enable the path for either input or output operations at any given time.
Solution Approach 2:
The patent implements dynamic control of the single path using enable signals and control logic. The circuit dynamically switches between input mode and output mode by activating appropriate transistors and control elements, allowing the same physical path to serve dual purposes. This dynamic allocation resolves the contradiction by providing reliable separated functionality (input vs. output) without the static area overhead of duplicate physical paths.
2Reliability
If termination resistors are added to prevent signal reflection, then signal integrity is improved, but capacitance loading increases
Solution Approach 1:
The patent applies termination resistance locally and selectively rather than uniformly across all signal paths. Termination resistors are implemented only at specific nodes where impedance matching is critical, such as at the output node when driving external devices. The control logic selectively activates termination functionality based on the operational mode (input or output), providing signal integrity where needed without adding unnecessary capacitance loading throughout the entire circuit.
Solution Approach 2:
The patent dynamically changes the termination resistance parameter based on operational requirements. The termination resistor is controlled by enable signals that activate it only during output operations when driving external devices, and deactivate it during input operations. This parameter change approach maintains signal integrity during output while minimizing capacitance loading during input operations, resolving the contradiction through conditional application.
3Area of stationary object
If switch elements are used to enable single-path input/output operations, then area is minimized, but device complexity increases
Solution Approach 1:
The patent implements multi-functional control elements that manage both input and output operations through a unified control scheme. The enable signals and control logic serve multiple purposes: they activate the appropriate path for input operations, activate the appropriate path for output operations, control termination resistor activation, and coordinate transistor switching. This universal control approach reduces device complexity compared to having separate control logic for each function, while still enabling the area-efficient single-path architecture.
4Area of stationary object
If a single path is used for both input and output operations, then area and capacitance loading are reduced, but signal reflection increases
Solution Approach 1:
The patent applies preliminary anti-action by proactively implementing termination resistance control to prevent signal reflection before it occurs. The control logic detects when the circuit is in output mode and activates the termination resistor in advance to match the impedance of the transmission line, preventing reflection of the output signal. Similarly, during input operations, the termination is configured to prevent reflection of incoming signals. This preliminary preventive measure eliminates the harmful reflection effect while maintaining the area-efficient single-path design.
Data Source
AI summary
An input/output circuit may include a driving unit including a first transistor coupled between a power supply voltage and a first node, and a second transistor coupled in series with the first transistor through the first node at an end of the second transistor. The input/output circuit may include switch elements coupled in parallel to a second node at another end of the second transistor, and the switch elements configured to be selectively turned on in an input operation and an output operation.