MOS Switching Circuits With Reduced Signal Swing for Lower Power
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Solution Overview
Problem
Current switching and logic circuits operate at full supply range, leading to unnecessarily high power consumption due to quadratic dependence on supply voltage, capacitive load, frequency, and activity factor.
Innovation Solution
Implementing a method that lowers the signal range of switching and logic circuits below the supply range by using positive and negative supply rails with generic device networks to establish constant voltage drops, decoupling signal range from biasing voltages, and providing AC signal coupling through capacitive networks, allowing for power-optimum amplitude swing independent of supply range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If full supply range is used for signal swing, then drive strength and speed are maximized, but power consumption increases quadratically
Solution Approach 1:
The patent segments the power consumption into dynamic and static components, and further segments the signal swing range from the supply voltage range. By using separate biasing circuits and AC coupling capacitors, the signal swing amplitude can be optimized independently to reduce dynamic power consumption while maintaining adequate drive strength for the application.
Solution Approach 2:
The patent changes the parameter of signal swing amplitude from being fixed at full supply range to being an independently optimizable parameter. Through biasing circuits that set reference voltages and AC coupling that blocks DC while passing AC signals, the signal swing can be reduced to the minimum necessary for reliable logic transitions, thereby reducing power consumption while maintaining drive strength.
2Reliability
If full supply range is used for signal swing, then noise margin is maximized, but power consumption increases
Solution Approach 1:
The patent applies partial action by using only the necessary portion of the supply voltage range for signal swing, rather than the full range. The biasing circuits establish reference voltages that create an optimized signal swing amplitude that is sufficient for reliable noise margins but smaller than the full supply range, thereby reducing power consumption while maintaining adequate noise immunity.
3Use of energy by stationary object
If signal range is reduced below supply range, then power consumption is optimized, but circuit complexity increases due to additional biasing and coupling components
Solution Approach 1:
The biasing circuits serve multiple functions: they establish reference voltages for the signal swing, provide DC biasing for the active devices, and set the operating point for optimal power consumption. The AC coupling capacitors simultaneously block DC voltage differences between stages while passing the AC signal components. This multi-functionality reduces the need for separate dedicated components, thereby limiting the increase in circuit complexity.
4Use of energy by moving object
If signal swing amplitude is reduced, then dynamic power consumption decreases, but drive strength may be insufficient
Solution Approach 1:
The patent introduces dynamics by allowing the signal swing amplitude to be independently optimized rather than fixed at full supply range. The biasing circuits can be designed to provide the minimum necessary swing amplitude for reliable logic transitions, and the AC coupling ensures that the reduced swing is adequately transmitted to the next stage, maintaining drive strength while reducing dynamic power consumption proportional to the square of the voltage swing.
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 reduces power consumption by allowing signal amplitude swing to be optimized based on frequency, activity factor, and technology characteristics, while increasing speed and drive strength of switching and logic circuits.
Implementation Method 1
providing AC signal coupling of active devices of the circuit by a capacitive network
Data Source
AI summary
The present disclosure relates to methods and circuits to lowering the signal range of switching or logic circuits below supply range. The circuits may have one or more stages. The supply levels can be set individually for each stage. This may realize amplifiers/attenuators, both digitally and analogically controlled, based on progression and/or modulation in the supply range from stage to stage. A chain of stages can provide the desired power gain by setting the supply progression according to the nature of the incoming signals. The signal levels are lowered by generic device networks comprising voltage sources providing voltages independent of currents flowing through. Decoupling the signal amplitude from DC biasing allows for the signal swing to be lower than threshold voltages of the active devices.