Pull-Up Circuit Feedback for Failsafe Low-Leakage I/O
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Solution Overview
Problem
The semiconductor industry faces challenges in maintaining circuit reliability and reducing power consumption as semiconductor process nodes shrink, particularly in ensuring failsafe operations and minimizing leakage current across varying voltage levels in mobile devices.
Innovation Solution
A novel pull-up circuit incorporating a control circuit, level shifter, and feedback mechanism that enables failsafe mode and near full-swing output voltage, utilizing PMOS and NMOS transistors to manage voltage transitions and isolate transistors during failsafe conditions, ensuring circuit reliability even with supply voltage failures or high voltage signal levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by stationary object
If the semiconductor process node is shrunk to reduce operating voltage and current consumption, then power consumption is reduced, but circuit reliability and control over leakage current deteriorate
Solution Approach 1:
The patent implements a feedback mechanism where the bulk potential of the first transistor is dynamically adjusted based on the output voltage level. A feedback circuit monitors the output voltage and controls the bulk-to-source voltage ratio, ensuring optimal transistor operation across different voltage levels. This feedback control maintains circuit reliability by preventing excessive leakage current while enabling reduced operating voltages for lower power consumption.
Solution Approach 2:
The patent dynamically changes the bulk potential parameter of the first transistor based on operating conditions. By adjusting the bulk-to-source voltage ratio according to the output voltage level, the circuit adapts transistor characteristics to maintain reliability. This parameter change approach allows the circuit to operate reliably at reduced voltages while controlling leakage current through optimized transistor biasing conditions.
2Object-generated harmful factors
If the bulk potential of the first transistor is controlled to reduce leakage current, then leakage current is reduced, but device complexity increases
Solution Approach 1:
The circuit employs self-service mechanisms where the bulk potential control is automatically adjusted based on the output voltage level without requiring external intervention. The feedback circuit autonomously monitors output conditions and regulates the bulk-to-source voltage ratio, enabling the transistor to self-optimize its operation. This self-service approach reduces leakage current while minimizing the need for complex external control circuitry.
Solution Approach 2:
The patent merges the bulk potential control function with the existing output stage circuitry. The control circuit for adjusting bulk potential is integrated into the pull-up circuit architecture, sharing components and control signals with the output voltage regulation mechanism. This merging approach reduces overall device complexity by consolidating control functions rather than adding separate independent control systems.
3Reliability
If a feedback mechanism is implemented to maintain circuit reliability during failsafe conditions, then circuit reliability is improved, but device complexity increases
Solution Approach 1:
The feedback mechanism implemented in the patent serves multiple functions simultaneously: it maintains circuit reliability during failsafe conditions, regulates the bulk-to-source voltage ratio for optimal transistor operation, and controls leakage current. By designing the feedback circuit to perform these multiple functions, the patent avoids adding separate dedicated circuits for each function, thereby improving reliability while limiting the increase in device complexity.
Data Source
AI summary
A device includes a pull-up circuit, first and second switches, and a feedback circuit. The pull-up circuit has a first terminal electrically coupled to a pad, and a second terminal electrically coupled to a first power node. The first switch has a first terminal electrically coupled to a first control terminal of the pull-up circuit, and a second terminal electrically coupled to a second control terminal of the pull-up circuit. The feedback circuit has a first terminal electrically coupled to the pad, and a feedback terminal. The second switch has a first terminal electrically coupled to the first control terminal of the pull-up circuit, a second terminal electrically coupled to the feedback terminal of the feedback circuit, and a control terminal electrically coupled to a second power node.