I/O Buffer Swing Reduction Circuit for BTI-Aware Gate Biasing
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Solution Overview
Problem
Bias Temperature Instability (BTI) effects cause performance degradation in MOSFETs, particularly in input/output (I/O) buffer circuits due to voltage swings from supply voltages, leading to reliability issues and overdesign trade-offs in existing techniques.
Innovation Solution
A swing reduction circuit is introduced, comprising p-type and n-type swing reduction circuits coupled to the gates of pMOSFETs and nMOSFETs in I/O buffer circuits, which adjust the voltage swing magnitude to mitigate BTI effects by increasing the lower bound of voltage for p-type MOSFETs and decreasing the higher bound for n-type MOSFETs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If voltage swing magnitude is increased to improve switching performance, then switching speed is improved, but BTI effects worsen causing reliability degradation
Solution Approach 1:
The circuit is segmented into three functional blocks: a first swing reduction circuit coupled to pMOSFET gates, a second swing reduction circuit coupled to nMOSFET gates, and a buffer circuit. Each segment handles voltage swing reduction for specific transistor types, allowing differentiated treatment to mitigate BTI effects while maintaining switching performance.
Solution Approach 2:
Swing reduction circuits are introduced as intermediary components between the supply voltage and the transistor gates. These intermediary circuits reduce the voltage swing magnitude before it reaches the transistors, thereby mitigating BTI effects without directly compromising the switching performance of the buffer circuit.
2Reliability
If overdesign is applied to ensure reliability under BTI effects, then circuit reliability is improved, but area and timing performance worsen
Solution Approach 1:
The invention changes the voltage swing parameter by introducing swing reduction circuits that actively reduce the voltage swing magnitude at transistor gates. This parameter change allows the circuit to operate reliably under BTI effects without requiring overdesign in terms of transistor sizing or adding redundant reliability circuits, thus avoiding area penalties.
3Reliability
If overdesign is applied to ensure reliability under BTI effects, then circuit reliability is improved, but timing performance worsens
Solution Approach 1:
The swing reduction circuits are designed to dynamically adjust voltage levels based on the operating conditions. By using dynamic voltage adjustment rather than static overdesign, the circuit maintains timing performance while achieving reliability under BTI effects. The dynamic nature allows optimal performance across different operating points without fixed overhead.
Data Source
AI summary
A circuit includes: a first type of swing reduction circuit coupled between an input/output pad and a buffer circuit; and a second type of swing reduction circuit coupled between the input/output pad and the buffer circuit, wherein the first type of swing reduction circuit is configured to increase a voltage received by respective gates of a first subset of transistors of the buffer circuit when a voltage applied on the input/output pad is equal to a first supply voltage, and the second type of swing reduction circuit is configured to reduce a voltage received by respective gates of a second subset of transistors of the buffer circuit when the voltage applied on the input/output pad is equal to a second supply voltage.