Isolator Circuit for Power Gating and Reverse Current Prevention
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Solution Overview
Problem
The increasing power consumption of processors in semiconductor devices poses a challenge, particularly when using power gating techniques, as it can lead to reverse current and increased consumption current due to intermediate potentials, especially when logic circuits are electrically connected.
Innovation Solution
A novel isolator circuit capable of two-way electrical disconnection is introduced, comprising two one-way isolator circuits that allow for the electrical disconnection of logic circuits from signal lines, reducing power consumption and preventing reverse current by using transistors with low off-state current and buffer structures for data holding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If power gating technique is used to reduce power consumption by stopping power feeding to logic circuits, then power consumption is reduced, but reverse current to power supply line or increase in consumption current may be caused due to intermediate potential
Solution Approach 1:
An isolator circuit is introduced as an intermediary component between logic circuits to prevent reverse current flow. The isolator includes transfer transistors that can electrically disconnect signal lines from logic circuits when power is gated, thereby preventing reverse current while maintaining the power saving benefit. The isolator acts as a mediator that allows safe power gating operation.
Solution Approach 2:
The power gating system is segmented into multiple independent components: logic circuits that can be independently powered down, isolator circuits that control disconnection, and buffer circuits that maintain signal integrity. This segmentation allows selective power gating of individual logic circuits without affecting the entire system, enabling reverse current prevention at specific locations.
2Productivity
If logic circuits are electrically connected to signal lines for data processing, then data processing capability is maintained, but power consumption increases when logic circuits are not in processing
Solution Approach 1:
The electrical connection between logic circuits and signal lines is made dynamic rather than static. Transfer transistors in the isolator circuit dynamically control the connection state based on whether the logic circuit is actively processing data or is in a low-power state. When processing is needed, the connection is established; when not needed, the connection is disconnected to save power.
Solution Approach 2:
The isolator circuit periodically establishes and disconnects electrical connections between logic circuits and signal lines based on processing requirements. During active processing periods, the connection is maintained for data flow; during idle periods, the connection is disconnected to reduce power consumption, creating a periodic on-off pattern that balances productivity and energy efficiency.
Data Source
AI summary
An isolator circuit capable of two-way electrical disconnection and a semiconductor device including the isolator circuit are provided. A data holding portion is provided in an isolator circuit without the need for additional provision of a data holding portion outside the isolator circuit, and data which is to be input to a logic circuit that is in an off state at this moment is stored in the data holding portion. The data holding portion may be formed using a transistor with small off-state current and a buffer. The buffer can include an inverter circuit and a clocked inverter circuit.