Output Driver Power Gating With Impedance-Matched Slice Control
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Solution Overview
Problem
In computing systems, the introduction of power control transistors to reduce leakage current in output drivers can undesirably adjust the impedance, leading to operational inefficiencies and signal integrity issues, particularly when the number of active slices changes during data transmission.
Innovation Solution
The implementation of multiple smaller transistors with a combined channel width equal to that of a single larger power control transistor, allowing the power state control circuit to adjust the channel width based on the number of active slices to maintain consistent impedance and reduce power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a single large power control transistor is used to reduce leakage current, then power consumption is reduced, but impedance is undesirably adjusted
Solution Approach 1:
The single large power control transistor is segmented into multiple smaller transistors with individually controllable gates. This segmentation allows selective activation of only the necessary number of transistors based on the number of active slices, thereby maintaining proper impedance while still achieving leakage current reduction when slices are inactive.
Solution Approach 2:
The power control structure is made dynamic by allowing the number of active power control transistors to change based on the number of active slices. The control circuit dynamically adjusts which transistors are activated, enabling the system to adapt impedance characteristics to match operational requirements while maintaining power savings during idle periods.
2Use of energy by moving object
If power control transistors are introduced to reduce leakage, then power efficiency is improved, but signal integrity deteriorates due to impedance adjustment
Solution Approach 1:
By segmenting the power control function across multiple transistors, the system can selectively activate only the necessary number of transistors to match active slices. This maintains signal integrity by preventing excessive impedance adjustment while still achieving power efficiency through selective power gating of inactive slices.
Solution Approach 2:
The system changes the operational parameters of the power control transistors by adjusting which specific transistors are activated based on the number of active slices. This parameter adjustment maintains the correct impedance relationship between the output driver and transmission line, thereby preserving signal integrity while improving power efficiency.
3Device complexity
If a fixed channel width power control transistor is used, then device complexity is reduced, but operational efficiency decreases when slice configuration changes
Solution Approach 1:
The power control structure is segmented into multiple independently controllable transistors, which increases structural complexity but enables dynamic adaptation to different slice configurations. This segmentation allows the system to maintain optimal operational efficiency across varying workloads by activating only the necessary number of transistors.
Solution Approach 2:
The power control system transitions from a fixed configuration to a dynamic one where the number of active transistors can be adjusted based on the number of active slices. This dynamic capability improves operational efficiency by preventing impedance mismatches that would occur with a fixed channel width design, while the added complexity is managed through systematic control logic.
Data Source
AI summary
The systems and methods described herein consider a first channel width of transistors of driver circuitry, where the first channel width may be set to match a second channel width of a power control transistor. A control circuit, for example, may match a second channel width of a set of power control transistors to the first channel width by turning on one or more of the set of power control transistors. Matching the width of the switches of driver circuitry and the width of the set of power control transistors may reduce losses by helping to maintain impedances of the driver circuitry.