Center-Swing CML Conversion for Full-Rail Single-Ended Output
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Solution Overview
Problem
Current integrated circuits face challenges in converting low-swing Current Mode Logic (CML) differential signals to full rail single-ended signals efficiently, which limits power consumption reduction and noise rejection in high-speed applications.
Innovation Solution
A system comprising a center-swing signal generator, push-pull center-swing driver, common-mode pre-emphasis module, and full-swing cross-coupled inverter gain stage is used to convert low-swing CML signals to full rail single-ended signals, leveraging push-pull swing drivers and common-mode pre-emphasis to optimize voltage swings and power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If low-swing CML differential signaling is used for high-speed data transfer, then power consumption is reduced and supply voltage is lowered, but conversion to full rail single-ended signal is required which complicates the circuit
Solution Approach 1:
The patent introduces a center-swing signal generator as an intermediary component that converts low-swing CML differential signals to center-swing signals, which are then processed by a full-swing cross-coupled inverter gain stage. This two-stage conversion process using an intermediary signal type resolves the complexity of direct conversion while maintaining power efficiency.
Solution Approach 2:
The signal conversion process is divided into two separate stages: first, the center-swing signal generator converts low-swing CML signals to center-swing signals; second, the full-swing cross-coupled inverter gain stage converts center-swing signals to full-rail single-ended signals. This segmentation allows each stage to be optimized independently, reducing overall circuit complexity.
2Adaptability or versatility
If CML and CMOS circuitry are combined in a single integrated circuit, then signal conversion is enabled, but efficient conversion from differential to full rail single-ended signal is challenging
Solution Approach 1:
The patent changes the voltage swing parameter through two sequential transformations: first from low-swing CML differential signals to center-swing signals with zero common-mode voltage, then to full-rail single-ended signals with maximum voltage swing. This parameter transformation approach enables efficient interoperability between CML and CMOS circuitry while maintaining conversion efficiency.
3Object-affected harmful factors
If full rail single-ended signal is generated from CML differential signal, then noise rejection is improved, but power consumption and propagation time become critical constraints at frequencies beyond 5 GHz
Solution Approach 1:
The full-swing cross-coupled inverter gain stage uses periodic switching action to generate full-rail single-ended signals from center-swing inputs. This periodic action enables the circuit to achieve full voltage swing and improved noise rejection while maintaining power efficiency through controlled switching cycles optimized for frequencies beyond 5 GHz.
4Object-affected harmful factors
If full rail single-ended signal is generated from CML differential signal, then noise rejection is improved, but propagation time increases
Solution Approach 1:
The center-swing signal generator performs preliminary conversion of low-swing CML differential signals to center-swing signals before the final full-swing conversion stage. This preliminary action prepares the signal in an optimal state for the subsequent full-swing conversion, minimizing propagation time while ensuring improved noise rejection in the final output.
Data Source
AI summary
Apparatus, systems, and methods are disclosed, such as those that comprise a center-swing signal generator that includes a push-pull center-swing driver coupled to a common-mode pre-emphasis module, the center-swing signal generator to receive a low swing current mode logic (CML) signal and output a center-swing signal, and a full-swing cross-coupled inverter coupled to the center-swing signal generator, the full-swing cross-coupled inverter to receive the center-swing signal and output a full-rail single-ended swing signal. Additional apparatus, systems, and methods are disclosed.