Dynamic Level Shifter Circuit for Faster Cross-Domain Signals
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Solution Overview
Problem
Integrated circuits with multiple power domains operating at different voltages face challenges in signal transmission across voltage boundaries, as existing level shifter circuits are either static and inefficient or lack a method to dynamically adjust voltage levels effectively.
Innovation Solution
A dynamic level shifter circuit and ring oscillator design that incorporates both dynamic and static level shifters in an alternating series, utilizing a precharge circuit, pull-down and pull-up circuits, and a half-keeper circuit to adjust voltage levels, along with a pulse generator to initiate and maintain oscillation, allowing for efficient signal transmission across power domains.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If static level shifter circuits are used to transfer signals across power domain boundaries, then signal transmission between different voltage domains is enabled, but transmission efficiency is insufficient and delay performance is poor
Solution Approach 1:
The patent applies dynamic logic circuits instead of static level shifters. The dynamic level shifter uses clocked operation with precharge and evaluation phases, allowing the circuit to actively drive signals during the evaluation phase rather than relying on weak static pull-up/pull-down networks. This dynamic operation significantly improves signal transmission speed and reduces delay across power domain boundaries.
Solution Approach 2:
The dynamic level shifter operates in periodic cycles consisting of a precharge phase (when clock is low) and an evaluation phase (when clock is high). During the precharge phase, the output node is precharged to a known state. During the evaluation phase, the actual signal transmission occurs based on the input data. This periodic operation enables faster signal propagation compared to continuous static operation.
2Speed
If dynamic level shifter circuits are used to improve signal transmission efficiency, then transmission speed increases, but circuit complexity increases
Solution Approach 1:
The dynamic level shifter is segmented into distinct functional blocks: a precharge circuit (PMOS transistor), a pull-down circuit (NMOS transistor), and a keeper circuit (weak PMOS). This segmentation allows each component to perform its specific function efficiently and makes the overall circuit easier to design, analyze, and integrate into larger systems despite the dynamic operation.
Solution Approach 2:
The patent introduces a keeper circuit as an intermediary element that maintains the output state during the clock cycle. This weak PMOS transistor acts as a mediator between the dynamic precharge/pull-down circuits and the subsequent static logic stages, ensuring stable signal levels while minimizing interference with the dynamic operation. This intermediary structure bridges the gap between dynamic speed advantages and static stability requirements.
3Productivity
If voltage levels are dynamically adjusted across power domains, then communication efficiency between processor cores and memory improves, but power consumption increases
Solution Approach 1:
The dynamic level shifter uses clocked operation where transistors are actively switched only during the evaluation phase for signal transmission. During the precharge phase, the circuit prepares for the next operation but does not actively drive signals. This dynamic switching reduces unnecessary power dissipation compared to static circuits that continuously maintain voltage levels through resistive paths, while still achieving fast communication when needed.
Data Source
AI summary
A dynamic level shifter circuit and a ring oscillator implemented using the same are disclosed. A dynamic level shifter may include a pull-down circuit and a pull-up circuit. The pull-up circuit may include an extra transistor configured to reduce the current through that circuit when the pull-down circuit is activated. A ring oscillator may be implemented using instances of the dynamic level shifter along with instances of a static level shifter. The ring oscillator may also include a pulse generator configured to initiate oscillation. The ring oscillator implemented with dynamic level shifters may be used in conjunction with another ring oscillator implemented using only static level shifters to compare relative performance levels of the static and dynamic level shifters.