SOI Switch Transistor Biasing for Disabled Circuit Leakage Reduction
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Solution Overview
Problem
Conventional techniques fail to adequately disconnect unwanted silicon-on-insulator (SOI) processors from the power supply, leading to increased power dissipation in integrated circuits (ICs), especially when redundant circuitry is not needed, which can reduce IC yield and increase manufacturing costs.
Innovation Solution
The method involves enabling or disabling digital circuits by biasing a switch transistor's gate voltage relative to the ground node, effectively interrupting power supply current to unused processors, thereby reducing power dissipation. This is achieved by setting the gate voltage of the switch transistor below the ground node's voltage potential, specifically between −0.05 V and −0.5 V, to control the leakage current and substrate voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional techniques are used to disable faulty circuits in SOI ICs, then circuit redundancy can be implemented, but leakage current increases and power dissipation is not adequately reduced
Solution Approach 1:
The patent applies parameter changes by adjusting the substrate voltage to a negative value (e.g., -0.7V to -1.2V relative to ground) when disabling SOI circuits. This voltage parameter change creates a reverse bias condition that effectively suppresses leakage current in the disabled circuits, thereby reducing power dissipation while maintaining the ability to enable/disable circuits for redundancy purposes
2Productivity
If redundant circuitry is kept active for potential replacement, then IC yield can be improved, but power consumption increases
Solution Approach 1:
The patent implements dynamics by dynamically adjusting the substrate voltage based on the operational state of circuits. When circuits are disabled (whether faulty or not needed), the substrate voltage is shifted to a negative value to minimize leakage. This dynamic control allows redundant circuits to be kept available for yield improvement while consuming minimal power when not in use
3Loss of energy
If switch transistor gate voltage is lowered to disable circuits, then leakage current is reduced, but voltage potential control becomes more complex
Solution Approach 1:
The patent applies universality by using a single substrate voltage control mechanism that serves multiple functions: it enables and disables circuits, controls leakage current, and manages power dissipation across the entire IC. This unified approach, rather than individual control circuits for each function, reduces overall device complexity despite the negative voltage requirement
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 significantly reduces power dissipation in ICs by minimizing leakage current and enabling the use of faulty ICs in less demanding applications, thereby enhancing yield and reducing manufacturing costs.
Implementation Method 1
disabling the digital circuit by biasing a gate terminal of the switch transistor below the voltage potential of the ground node
Data Source
AI summary
Methods and apparatus provide for enabling a digital circuit by biasing at least one switch transistor ON such that a voltage potential of a virtual ground node is substantially equal to a voltage potential of a ground node for a power supply to the digital circuit, wherein the digital circuit is implemented using a plurality of transistors in a silicon-on-insulator (SOI) arrangement and at least some of the transistors are referenced to the virtual ground node; and disabling the digital circuit by biasing a gate terminal of the switch transistor below the voltage potential of the ground node.