Pull-Up Driver Circuit for Duty Ratio Stable Low-Swing Signaling
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Solution Overview
Problem
Semiconductor devices face deterioration in signal integrity characteristics due to unintended changes in duty ratio when swing range and level of output signals are adjusted, leading to decreased eye margin and increased power consumption.
Innovation Solution
A semiconductor device with a pull-up circuit comprising NMOS and PMOS transistors, and a control circuit that adjusts the resistance of these circuits based on pull-up codes to maintain a stable duty ratio, utilizing a combination of NMOS and PMOS transistors in parallel to optimize signal transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the swing range and swing level of the output signal are changed to adjust operation modes, then the driver can adapt to different communication standards and operating conditions, but the duty ratio of the output signal is unintentionally changed causing deterioration of signal integrity characteristics
Solution Approach 1:
The control circuit includes a duty ratio detection unit that detects the duty ratio of the output signal and feeds this information back to a resistance adjustment unit. Based on the detected duty ratio, the control circuit adjusts the resistance of the pull-up circuit to compensate for duty ratio deviations, thereby maintaining signal integrity while operating in different operation modes.
Solution Approach 2:
The pull-up circuit uses adjustable resistance rather than fixed resistance, allowing the circuit parameters to dynamically change based on the detected duty ratio. This dynamic adjustment enables the driver to maintain optimal signal characteristics across varying operation modes while compensating for duty ratio changes.
2Adaptability or versatility
If the swing range and swing level are adjusted for different operation modes, then the driver can support multiple communication standards, but the eye margin deteriorates due to duty ratio changes
Solution Approach 1:
The duty ratio detection unit continuously monitors the output signal duty ratio and provides feedback to the resistance adjustment unit. This feedback mechanism enables real-time compensation for duty ratio changes that would otherwise degrade eye margin, allowing the driver to maintain adequate eye margin across different communication standards and operation modes.
3Device complexity
If conventional pull-up circuits are used without duty ratio compensation, then the circuit structure remains simple, but power consumption increases due to duty ratio deterioration
Solution Approach 1:
The control circuit incorporates a duty ratio detection unit that monitors the output signal and provides feedback to adjust the pull-up circuit resistance. This feedback mechanism enables the circuit to optimize power consumption by adjusting resistance based on actual duty ratio conditions, preventing excessive power consumption that would occur with duty ratio deterioration.
Solution Approach 2:
The control circuit automatically detects duty ratio changes and adjusts the pull-up circuit resistance without external intervention. This self-service capability allows the circuit to autonomously optimize its power consumption based on operating conditions, maintaining lower power consumption while supporting multiple operation modes.
Data Source
AI summary
A semiconductor device includes a first pull-up circuit connected between a first power node supplying a first power voltage and an output node through which a signal is output, and including a plurality of NMOS transistors; a second pull-up circuit connected in parallel to the first pull-up circuit between the first power node and the output node and including a plurality of PMOS transistors; and a control circuit outputting a first pull-up code to the first pull-up circuit and outputting the second pull-up code to the second pull-up circuit. In a first operating mode, the signal swings between a first low level lower than the first power voltage, and a first high level lower than ½ times the first power voltage, resistance of the first pull-up circuit is determined based on the first pull-up code, and resistance of the second pull-up circuit is determined based on the second pull-up code.