Communication Signal Generating Device Impedance Control
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Solution Overview
Problem
Communication systems with network structures experience signal reflections at branch points, leading to ringing waveforms, and existing solutions that control output impedances increase the number of components in the system.
Innovation Solution
A communication signal generating device with a switching element that connects the communication line to a ground or a constant voltage source, using a driving means to generate signals at different levels by varying the output impedance of the switching element during one bit time, reducing high-frequency components and thus ringing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an output impedance varying section is added to each digital signal output circuit to control output impedance and reduce ringing, then signal integrity is improved, but the number of components increases
Solution Approach 1:
The patent combines the output impedance control function with the existing output buffer by making the buffer's output impedance dynamically variable. Instead of adding a separate impedance control circuit, the invention integrates the impedance variation capability directly into the output buffer's operating states, thereby achieving ringing reduction without increasing component count.
Solution Approach 2:
The patent employs dynamic impedance control by varying the output impedance of the buffer according to the signal level. The buffer operates in different states (first operating state for high signal levels, second operating state for low signal levels) with differently controlled output impedances, allowing the system to adaptively reduce ringing while maintaining signal integrity.
2Object-generated harmful factors
If output impedance is controlled to shape signal waveform and reduce high-frequency components, then ringing is reduced, but device complexity increases
Solution Approach 1:
The patent dynamically adjusts the output impedance based on the instantaneous signal level. When the signal level is high, the buffer operates in a first state with controlled impedance; when the signal level is low, it operates in a second state with different impedance control. This dynamic adaptation reduces ringing effectively without requiring additional static impedance control components.
Solution Approach 2:
The patent changes the operating parameters (impedance levels, operating states) of the existing buffer according to the signal characteristics. By varying the impedance parameter dynamically based on signal level thresholds, the system reduces high-frequency components and ringing without adding new hardware, thus avoiding increased device complexity.
Data Source
AI summary
The communication signal generating device is for use in a communication system where communication signals each of which is set at a first level or a second level are exchanged among a plurality of communication apparatuses through a communication line. The communication signal generating device includes a switching element provided in a communication line to connect the communication line to a ground or a constant voltage source, and a driving means to generate a first communication signal at the first level by turning on the switching element to thereby pass a certain current to the communication line, and generate a second communication signal at the second level by turning off the switching element to thereby pass no current to the communication line. The driving means is configured to gradually increase an output impedance of the switching element during one bit time of the first communication signal.