Selective Back-Biasing Circuit for GPU Leakage Control
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Solution Overview
Problem
As device geometries scale down, leakage power in transistor circuits increases exponentially, becoming a dominant factor in power consumption during standby mode, particularly in mobile devices, while existing methods to reduce leakage power either decrease circuit performance or fail to dynamically adjust threshold voltage based on operating modes.
Innovation Solution
A dynamic leakage control circuit that uses back biasing techniques with separate power rails and adjustable voltage regulators to alter the threshold voltage of transistors, enabling or disabling back biasing based on operating modes, such as standby or active modes, to reduce leakage current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If device geometries are scaled down to reduce dynamic power consumption, then dynamic power is reduced, but leakage power increases exponentially
Solution Approach 1:
The patent applies dynamic threshold voltage adjustment by switching between different power rails (first power rail for active mode, second power rail for standby mode) to dynamically change the transistor threshold voltage based on operating conditions. This resolves the contradiction by making the threshold voltage adaptive rather than fixed, allowing the system to optimize between dynamic power and leakage power trade-offs in different operating modes.
Solution Approach 2:
The patent changes the threshold voltage parameter of transistors by selectively connecting to different power rails with different voltage levels. During active mode, a lower threshold voltage is maintained for high performance, while during standby mode, a higher threshold voltage is applied to reduce leakage power. This parameter change directly addresses the contradiction by adjusting the threshold voltage to match operational requirements.
2Loss of energy
If threshold voltage is increased to reduce leakage power, then leakage power decreases, but switching speed decreases
Solution Approach 1:
The patent dynamically adjusts the threshold voltage based on the operating mode by switching between power rails. During active mode, the threshold voltage is kept low to maintain high switching speed and performance. During standby mode, the threshold voltage is increased to reduce leakage power. This dynamic adjustment resolves the contradiction by applying different threshold voltage levels appropriate for each operational state.
Solution Approach 2:
The patent employs periodic switching between different power rail configurations based on operational mode transitions. The threshold voltage is periodically adjusted between low and high states corresponding to active and standby modes respectively, allowing the system to alternate between performance-optimized and power-saving states, thus resolving the speed-leakage power trade-off.
3Loss of energy
If operating voltage is reduced to reduce leakage power, then leakage power decreases, but circuit performance decreases
Solution Approach 1:
The patent changes the threshold voltage parameter independently of the operating voltage by selectively connecting to different power rails. This allows leakage power reduction through threshold voltage adjustment without proportionally reducing the operating voltage, thereby maintaining circuit performance while reducing leakage power in standby mode.
4Loss of energy
If present leakage reduction methods are used, then leakage power is reduced, but they do not dynamically adjust threshold voltage based on operating mode
Solution Approach 1:
The patent implements dynamic threshold voltage adjustment by using multiple power rails that can be selectively connected based on operating mode. The system transitions between active and standby modes and accordingly switches between different power rail configurations, enabling real-time adaptation of threshold voltage to current operational requirements. This resolves the contradiction by adding dynamic adaptability to leakage power reduction.
Solution Approach 2:
The patent employs feedback mechanisms through mode detection circuitry that monitors the operational state (active or standby) and accordingly controls the selection of power rails. This feedback loop ensures the threshold voltage is continuously adjusted to match the current operating mode, providing adaptive leakage power reduction that responds to changing operational conditions.
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
Effectively reduces leakage power without significantly impacting switching speed or performance, allowing for flexible power management in transistor circuits, especially in graphics processor units, by dynamically adjusting the threshold voltage based on operating conditions.
Implementation Method 1
A dynamic leakage control circuit selectively enables back biasing of transistors in a transistor circuit during particular modes of operation to reduce leakage power of the transistors
Data Source
AI summary
Embodiments of a dynamic leakage control circuit for use with graphics processor circuitry are described. The dynamic leakage control circuit selectively enables back biasing of the transistors comprising the graphics processor circuits during particular modes of operation. The back biasing levels are controlled by two separate power rails. A first power rail is coupled to an existing power supply and the second power rail is coupled to a separate adjustable voltage regulator. A separate voltage regulator may also be provided for the first power rail. A hardware-based state machine or software process is programmed to detect the occurrence of one or more modes of operation and adjust the voltage regulators for the first and second power rails to either enable or disable the back biasing state of the circuit, or alter the threshold voltage of the circuit within a specified voltage range.