Low-Swing Dynamic Circuit With Threshold-Controlled Precharge
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Solution Overview
Problem
Dynamic circuits face high power consumption and leakage issues due to pre-charge voltage levels, leading to false detections and increased power dissipation, especially when pull-down circuitry discharges dynamically charged nodes before the evaluation interval.
Innovation Solution
The introduction of DC keeper circuitry with adjustable pull-up resistance proportional to the pre-charge level, and the use of multiple charge circuits to maintain the dynamic node voltage, reducing leakage and power dissipation by controlling the pre-charge and discharge levels, and employing a level detector to manage charging based on voltage thresholds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the pre-charge voltage level is increased to ensure proper logic high detection, then the reliability of logic detection is improved, but the power consumption and leakage current increase
Solution Approach 1:
The patent implements a dynamic pre-charge voltage adjustment mechanism where the voltage level is adaptively controlled based on circuit state. The pull-up resistance is made adjustable to dynamically regulate the pre-charge current, allowing the circuit to maintain reliable logic high levels while minimizing unnecessary power consumption during stable states.
Solution Approach 2:
The invention changes the voltage parameter from a fixed high level to a controllable variable level. By adjusting the pre-charge voltage to be proportional to a reference voltage rather than using a fixed supply voltage, the circuit can optimize between detection reliability and power consumption by selecting appropriate voltage levels for different operating conditions.
2Reliability
If the pre-charge voltage is maintained at a high level to prevent false low detections, then the reliability is improved, but the leakage power dissipation increases
Solution Approach 1:
The patent incorporates a feedback mechanism through the level detector that monitors the dynamic node voltage and provides control signals to adjust the pre-charge operation. This feedback allows the circuit to maintain the voltage only when necessary for reliable detection while reducing or disabling pre-charge current during stable periods, thereby minimizing leakage power dissipation.
Solution Approach 2:
The pre-charge operation is implemented as a periodic or conditional action rather than a continuous process. The charge pump is activated only during specific phases (pre-charge interval) and controlled by clock signals, allowing the circuit to maintain reliability during critical periods while reducing power consumption during non-critical periods when the voltage level is stable.
3Speed
If the pull-up resistance is reduced to speed up charging of the dynamic node, then the charging speed is improved, but the leakage current increases
Solution Approach 1:
The pull-up resistance is implemented as a dynamic component that can adjust its resistance value based on operating conditions. During pre-charge phases, the resistance is reduced to enable fast charging of the dynamic node. During stable periods, the resistance is increased to minimize leakage current, thus resolving the contradiction between charging speed and leakage current.
4Reliability
If the dynamic circuit uses full rail-to-rail voltage swing, then the noise margin is improved, but the power consumption increases
Solution Approach 1:
The patent applies different voltage swing characteristics to different parts of the circuit or different operating conditions. Instead of using full rail-to-rail swing universally, the circuit uses reduced voltage swing (low-swing) operation for internal nodes where full swing is not necessary, while maintaining adequate noise margins through careful design of the dynamic node voltage levels proportional to reference voltages.
Data Source
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AI summary
Embodiments of the present disclosure enable low swing dynamic circuits with reduced dynamic power and leakage power. In an embodiment, a level detector circuit monitors the pre-charge voltage level of the dynamic node of a dynamic circuit and discontinues the charging of the dynamic node when the pre-charge voltage exceeds a logic high reference voltage. The logic high reference voltage is selected below a supply voltage of the dynamic circuit, resulting in a low swing dynamic circuit. In another embodiment, the pull-down logic circuitry is disconnected from the dynamic node when the dynamic node voltage falls below a logic low reference voltage, above a ground voltage. In another embodiment, a DC keeper circuit of the dynamic circuit is configured based on the pre-charge level of the dynamic node.