Low-Swing Dynamic Circuit with Level-Detected Precharge Control
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Solution Overview
Problem
Dynamic circuits face high power consumption and leakage issues due to false discharges caused by leakage currents, leading to inaccurate logic detections during evaluation intervals.
Innovation Solution
The implementation of DC keeper circuitry with adjustable pull-up resistance and programmable pre-charge and discharge voltages to minimize leakage and dynamic power dissipation, using level detectors and charge circuits to control the charging and discharging processes based on the pre-charge level of the dynamic node.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If dynamic circuits use full rail-to-rail voltage swing, then logic detection accuracy is improved, but power consumption increases
Solution Approach 1:
The patent changes the voltage swing parameter from full rail-to-rail to a reduced swing around a mid-rail reference voltage. The dynamic node swings between Vref - Vswing and Vref + Vswing, where Vswing is less than the full supply voltage range. This parameter change reduces power consumption while maintaining sufficient logic detection accuracy through the use of differential sensing and reference voltage comparison.
2Reliability
If pre-charge voltage is increased to ensure logic high level, then noise margin is improved, but leakage current increases causing false discharges
Solution Approach 1:
The patent converts the harmful leakage current effect into a beneficial mechanism by using a weakened pull-down device that intentionally allows controlled leakage. This controlled leakage serves as a discharge path that can be precisely managed through the gate control mechanism, preventing false discharges while maintaining noise margins. The harm of leakage is transformed into a controllable feature rather than an uncontrollable defect.
Solution Approach 2:
The patent implements dynamic control of the pull-down device through a control signal that adjusts its conductivity. During the evaluation phase, the pull-down device is weakened to reduce leakage current, while during other phases it can be strengthened for proper logic operation. This dynamic adjustment allows the circuit to adapt its characteristics to different operational requirements, balancing noise margin and leakage current.
3Stability of the object's composition
If keeper circuitry with strong pull-up is used to maintain dynamic node voltage, then voltage stability is improved, but power consumption increases
Solution Approach 1:
The keeper circuitry uses a dynamically controllable pull-up device whose strength is adjusted based on operational phase. During the pre-charge phase, the pull-up is strong to quickly establish the logic high level. During the evaluation and hold phases, the pull-up is weakened to minimize static power consumption while maintaining sufficient voltage stability through the reduced swing design and controlled leakage paths.
Data Source
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.