SOI Transistor Reverse Body Bias Power Island Isolation
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Solution Overview
Problem
Integrated circuits face challenges in reducing power consumption during low power or standby modes due to the footprint contribution of switches and isolation cells required for power islands, which increase the circuit size.
Innovation Solution
The use of silicon on insulator (SOI) transistors with a biasing circuit that applies a reverse body bias voltage to disable output terminals, reducing leakage current and eliminating the need for isolation cells, thereby minimizing power dissipation and area usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If switches and isolation cells are added to create power islands for reducing power consumption, then power savings are achieved, but the footprint of the integrated circuit increases
Solution Approach 1:
The patent extracts and eliminates the isolation cells from the power island structure by using fully depleted SOI transistors with reverse body bias. These transistors inherently provide isolation when disabled, removing the need for separate isolation cells and reducing the overall circuit footprint while maintaining power savings.
Solution Approach 2:
The fully depleted SOI transistor serves multiple functions: it acts as both the functional switching element and the isolation element when reverse body biased. This multi-functionality eliminates the need for separate isolation cells, reducing area while maintaining both power savings and isolation capabilities.
2Reliability
If isolation cells are used to clamp floating inputs in power islands, then leakage is prevented, but the device complexity increases
Solution Approach 1:
The patent removes isolation cells from the circuit structure by relying on the inherent isolation properties of fully depleted SOI transistors under reverse body bias. The disabled transistors naturally clamp floating inputs and prevent leakage without requiring additional isolation components.
Solution Approach 2:
The fully depleted SOI transistor provides its own isolation and leakage prevention functionality when reverse body biased. The transistor inherently clamps floating inputs and prevents leakage currents without requiring external isolation cells, making the system self-sufficient.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively reduces power consumption and silicon area by enabling efficient switching off of power islands with negligible leakage current, allowing for smaller integrated circuits while maintaining functionality.
Implementation Method 1
a biasing circuit configured to control an operational voltage supplied to the functional circuit. The biasing circuit may be configured to disable the one or more output terminals by controlling the reverse body bias voltage supplied to reverse body bias the one or more transistors
Data Source
AI summary
A functional circuit includes at least one silicon on insulator (SOI) transistor and at least one output terminal. A biasing circuit controls an operational voltage supplied to the functional circuit. The biasing circuit disables the at least one output terminal by controlling a reverse body bias voltage supplied to reverse body bias the at least one SOI transistor.