Parallel Pull-Up Driver Control for Low-Capacitance Signal Strength
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Solution Overview
Problem
Semiconductor devices face issues with increased input/output capacitance and circuit area, as well as resistance mismatch due to ZQ calibration, particularly in drivers with signal strength adjustment functions.
Innovation Solution
The semiconductor device employs a driver configuration with parallel-connected unit circuits and a controller to adjust resistance and signal strength by controlling N-bit codes, shifting codes, and varying the number of active unit circuits to minimize capacitance and mismatch.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a driver is implemented with a function to adjust the strength of an output signal, then signal strength adjustment capability is improved, but input/output capacitance and circuit area increase
Solution Approach 1:
The driver is divided into multiple unit circuits (first unit circuit, second unit circuit, etc.) that are connected in parallel. Each unit circuit contains a specific number of switch elements that can be independently controlled. This segmentation allows the driver to adjust output signal strength by selectively activating different combinations of unit circuits, thereby providing adaptability without requiring a single large complex circuit that would increase capacitance.
Solution Approach 2:
The driver employs dynamic control through N-bit control codes that can selectively turn on or off specific switch elements within unit circuits. This dynamic switching capability allows the driver to adjust its output signal strength in real-time by changing the control code, enabling adaptability without permanently increasing the circuit's physical size or capacitance.
2Adaptability or versatility
If a driver is implemented with a function to adjust the strength of an output signal, then signal strength adjustment capability is improved, but circuit area increases
Solution Approach 1:
The driver is divided into multiple unit circuits (first unit circuit, second unit circuit, etc.) that are connected in parallel. Each unit circuit contains a specific number of switch elements that can be independently controlled. This segmentation allows the driver to adjust output signal strength by selectively activating different combinations of unit circuits, thereby providing adaptability without requiring a single large complex circuit that would increase capacitance.
Solution Approach 2:
Multiple unit circuits are connected in parallel between the power node and output node, sharing common control logic and structure. This merging approach allows the driver to achieve multiple signal strength levels using a standardized repeating unit, reducing the overall circuit area compared to implementing separate adjustment mechanisms for each signal level.
3Measurement precision
If ZQ calibration is performed to determine driver resistance, then resistance measurement accuracy is improved, but resistance mismatch occurs between calibrated and actual resistance
Solution Approach 1:
The driver performs ZQ calibration in advance to determine the actual resistance characteristics. Based on the calibration results, N-bit control codes are pre-calculated and stored that will produce the desired output signal strengths. This preliminary action ensures that when the driver operates, it uses pre-compensated control codes that account for the actual resistance, thereby eliminating mismatch between calibrated and actual performance.
Solution Approach 2:
The ZQ calibration process provides feedback about the actual driver resistance to the control logic. This feedback is used to adjust the control codes so that the driver compensates for any resistance variations. The feedback mechanism ensures that the actual output signal strength matches the intended strength despite resistance mismatches.
Data Source
AI summary
A semiconductor device includes a first power node configured to supply a first power supply voltage, a pull-up circuit electrically connected between the first power node and an output node that is configured to output a signal, and a controller configured to output a pull-up control code to the pull-up circuit. The pull-up circuit includes a plurality of unit circuits electrically connected to each other in parallel between the first power node and the output node, and the plurality of unit circuits include a first unit circuit and a second unit circuit. The number of current paths provided by the first unit circuit between the first power node and the output node is different from the number of current paths provided by the second unit circuit between the first power node and the output node.