Auxiliary Driver Circuit for Parasitic Capacitance Overshoot Control
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Solution Overview
Problem
In CMOS semiconductor devices, overshoot and undershoot due to parasitic capacitance lead to signal noise and reduced transmission quality, especially when high-speed operation is emphasized, and existing solutions like terminating resistors either reduce signal amplitude or increase power consumption.
Innovation Solution
A semiconductor device with a main driver and an auxiliary driver, controlled by a detection and control system that assists the output signal change until it reaches a specific voltage level and then suppresses further change, using detection parts to generate control signals for the auxiliary driver to manage voltage levels and prevent overshoot and undershoot.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If terminating resistors are connected to suppress overshoot and undershoot, then signal voltage level stability is improved, but signal amplitude decreases and power consumption increases
Solution Approach 1:
The patent applies dynamics by making the second driver's operation state changeable based on signal voltage level. The second driver operates in different modes (first operation state assisting voltage change, second operation state suppressing voltage change) depending on real-time voltage conditions, thereby dynamically controlling power consumption while maintaining signal stability without constant resistor-based termination
Solution Approach 2:
The patent changes the operational parameters of the second driver based on detected signal voltage levels. When voltage reaches certain thresholds, the control part switches the second driver between different operation states, effectively adjusting system behavior to reduce power consumption while preventing overshoot and undershoot
2Reliability
If terminating resistors are connected to reduce overshoot and undershoot, then signal voltage stability is improved, but signal transmission speed decreases
Solution Approach 1:
The system dynamically adjusts the second driver's operation state based on real-time voltage detection. During voltage transition phases, the second driver assists in rapid change (first operation state), and only suppresses when voltage reaches target levels (second operation state), thereby maintaining high-speed transmission while ensuring voltage stability
Solution Approach 2:
The detection part continuously monitors signal voltage level and feeds this information to the control part, which adjusts the second driver's operation accordingly. This feedback mechanism enables the system to respond to voltage conditions in real-time, optimizing both transmission speed and voltage stability without the need for slow-acting terminating resistors
3Speed
If high-speed operation is emphasized to improve signal change speed, then transmission speed is improved, but overshoot and undershoot increase due to parasitic capacitance
Solution Approach 1:
The second driver acts as an intermediary element that mediates between the first driver's high-speed switching and the parasitic capacitance effects. By controlling the second driver's operation states based on voltage detection, it intermediate the conflict between fast switching and voltage stability, suppressing overshoot and undershoot without sacrificing transmission speed
Data Source
AI summary
A second driver is provided in addition to a first driver outputting an output signal in accordance with a voltage of an input signal. When the output signal changes from a first voltage level to a second voltage level in accordance with a voltage change of the input signal, a control part controls the second driver to assist the signal change during a period from a change start time until the output signal exceeds a third voltage level. The control part controls the second driver to suppress the signal change during a period from the time when the output signal exceeds the third voltage level until it reaches the second voltage level.