Transceiver Oscillation Reduction via RC Damping Network
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Solution Overview
Problem
In bus systems, particularly in CAN bus systems, there is a tendency for oscillation during transitions from dominant to recessive bit states, leading to increased bit times and reduced transmission rates due to insufficient damping, which can result in incorrect state recognition by transceivers.
Innovation Solution
A transceiver with an oscillation reduction unit comprising an R-C network, consisting of capacitors and resistors connected between bus wires and ground, is used to dampen oscillations, allowing for faster bit transitions and increased transmission rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the bit time is extended to sufficiently dampen oscillation during transition from dominant to recessive state, then oscillation is reduced and reliable detection is improved, but transmission rate decreases
Solution Approach 1:
An RC network (comprising a capacitor and resistor) is introduced as an intermediary damping element connected in parallel with the termination resistor. This RC network acts as a mediator that specifically targets and dampens oscillations during state transitions without affecting the overall bus impedance or requiring changes to the fundamental communication protocol, thereby resolving the contradiction between reliable detection and transmission rate.
Solution Approach 2:
The damping characteristics of the bus system are modified by changing the electrical parameters through the RC network. By selecting specific values for the capacitor and resistor, the damping effect can be optimized to suppress oscillations during transitions while maintaining the bit time short enough for high transmission rates, thus resolving the contradiction between reliability and productivity.
2Reliability
If the bit time is extended to dampen oscillation, then transmission reliability is improved, but bit time increases leading to slower communication
Solution Approach 1:
The RC network serves as a localized damping intermediary that addresses oscillation issues without requiring global parameter changes. This allows the bit time to remain short for fast communication while the RC network provides the necessary damping effect during transitions, resolving the contradiction between reliability and time loss.
Solution Approach 2:
Instead of extending the bit time for all communication, the RC network provides targeted damping action only during the critical transition periods when oscillations occur. This partial action approach maintains short bit times for data transmission while providing sufficient damping where needed, resolving the contradiction between reliability and time efficiency.
3Stability of the object's composition
If damping elements are added to reduce oscillation, then transmission stability is improved, but device complexity increases
Solution Approach 1:
The RC network is a simple, well-understood circuit configuration that can be easily integrated into existing bus systems. The capacitor and resistor are standard components with predictable behavior, making the solution straightforward to implement and analyze, thus achieving transmission stability without significantly increasing device complexity.
Solution Approach 2:
The damping effect is achieved through careful selection of RC component values rather than complex circuit topologies. By adjusting the resistance and capacitance values, optimal damping can be achieved with minimal additional components, resolving the contradiction between stability and complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution reduces oscillation duration, enhances transmission speed, provides design flexibility for bus topologies, and improves interference immunity by shifting emission frequencies away from critical ranges, thereby increasing data transfer rates and reducing errors.
Implementation Method 1
a vibration reduction unit for damping a vibration of the bus signal that develops on the bus wires when the transmit signal transitions from a dominant bus state to a recessive bus state
Implementation Method 2
the vibration reduction unit has a series circuit of a first capacitor and a first resistor that can be connected between the first bus wire and a ground connection
Data Source
Figure 1
Figure 2
Figure 3A~5B
AI summary
The invention relates to a transceiver (12; 120; 1200) for a bus system (1) and to a method for reducing an oscillation inclination upon transitioning between different bit states. The transceiver (12; 120; 1200) has a transmitter (121) for transmitting a transmission signal (TxD) to a first bus wire (41) of a bus (40) of the bus system (1), wherein an exclusive collision-free access of a participant station (10, 20, 30, 100) to the bus (40) of the bus system (1) is at least temporarily ensured in the bus system (1), and for transmitting the transmission signal (TxD) to a second bus wire (42) of the bus (40), and the transceiver also has an oscillation reduction unit (15; 150) for damping an oscillation of the bus signal (CAN_H, CAN_L) set on the bus wires (41, 42) upon a transition of the transmission signal (TxD) from a dominant bus state (402) to a recessive bus state (401). The oscillation reduction unit (15; 150) has a series circuit of a first capacitor (151) and a first resistor (152) which can be switched between the first bus wire (41) and a connection (44) to ground, and/or the oscillation reduction unit (15; 150) has a series circuit of a second capacitor (153) and a second resistor (154) which can be switched between the second bus wire (42) and a connection (44) to ground.