Semiconductor Output Buffer with Negative Pull-Down for Reflection Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing semiconductor devices experience signal quality deterioration due to reflection at bifurcated ends, particularly in communication schemes with small amplitudes, which conventional impedance calibration circuits fail to effectively address.
Innovation Solution
The semiconductor device employs a negative-voltage pull-down circuit to suppress signal quality deterioration by performing pull-down to a voltage lower than ground when the signal transitions from a high level to a low level, synchronized with the timing of reflection from bifurcated ends.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional impedance calibration circuit is used, then impedance adjustment is achieved, but signal quality deteriorates due to reflection at bifurcated ends
Solution Approach 1:
The invention applies preliminary anti-action by generating a negative voltage pulse before the reflected signal arrives at the reception buffer. This preemptive counter-action cancels out the harmful reflection effect by pulling the signal level down in advance, preventing the reflection-induced delay from degrading signal quality at the bifurcated end.
Solution Approach 2:
The invention implements preliminary action by detecting the signal transition at the output buffer and generating a control signal that triggers the negative voltage pulse before the reflection occurs. The delay circuit is configured to time the pull-down action precisely before the reflected signal would interfere with the original signal, thereby preventing signal quality deterioration.
2Use of energy by moving object
If communication schemes with small amplitudes are employed, then power consumption is reduced, but signal quality deteriorates prominently due to reflection
Solution Approach 1:
The invention applies parameter changes by dynamically altering the voltage level parameter through negative voltage pull-down. By changing the signal voltage parameter to a negative level temporarily, the system counteracts the reflection effect without requiring increased communication signal amplitude, thus maintaining low power consumption while improving signal quality.
3Reliability
If a negative voltage pull-down circuit is added, then signal quality improves by suppressing reflection, but device complexity increases
Solution Approach 1:
The invention implements universality by designing the negative voltage pull-down circuit to serve multiple functions: it detects signal transitions, generates timing control signals, produces the negative voltage pulse, and suppresses reflection effects. This multi-functional approach consolidates what could be separate circuits into a unified structure, reducing overall device complexity while maintaining signal quality improvement.
Data Source
AI summary
A semiconductor device is capable of suppressing deterioration in signal quality due to an effect of reflection even when it employs a communication scheme in which a signal at a first level has a first voltage margin relative to a first reference voltage that is equal to a ground voltage and the signal at a second level has a second voltage margin relative to a second reference voltage, the second voltage margin being greater than the first voltage margin. The semiconductor device includes an output buffer configured to transmit data through the signal according to on/off states of a first transistor group and a second transistor group, and a control circuit configured to perform pull-down of a voltage level of the signal by a third reference voltage lower than the first reference voltage when the signal outputted from the output buffer transitions from the second level to the first level.