Bus System Circuit for Impedance Stabilization

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Solution Overview

Problem

Long-lasting oscillations in bus voltage due to improper termination or topology lead to error-prone data transmission, especially with increased transmission rates, and existing solutions like masking oscillations or on-chip termination are inadequate.

Innovation Solution

A circuit with a measurement, detection, and resistance circuit that adjusts the resistance between bus connections to maintain a minimum impedance of 50 ohms, stabilizing communication by dynamically determining and setting a second resistance value based on measured conditions, including a time window and number of subscriber stations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If transmission rate is increased to improve productivity, then data transmission speed is improved, but bus voltage oscillations become more problematic and error-prone

Engineering Contradiction:
Improvedata transmission speedVSAvoiddata transmission reliability
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The measuring circuit proactively measures the resistance value between bus connections before oscillations can cause errors, and the determination circuit pre-calculates the appropriate resistance setting. This preliminary measurement and adjustment approach allows the system to prevent oscillation-related errors before they occur during high-speed data transmission.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system continuously measures the actual resistance value between bus connections using the measuring circuit, compares it with the target resistance value, and adjusts the termination resistance accordingly. This closed-loop feedback mechanism ensures that the bus system maintains optimal termination resistance even during high-speed operation, preventing voltage oscillations that would otherwise compromise data transmission reliability.

Inventive Principle:
Principle #23Feedback

2Stability of the object's composition

If termination resistance is adjusted to reduce oscillations, then bus voltage stability is improved, but system complexity increases due to additional measurement and control circuits

Engineering Contradiction:
Improvebus voltage stabilityVSAvoidcircuit complexity
Core Design Contradiction:
Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The measuring circuit, determination circuit, and resistance adjustment functionality are integrated into a single unified circuit module. The measuring circuit directly interfaces with the determination circuit, which in turn controls the resistance setting, creating a compact integrated solution that reduces overall system complexity while maintaining bus voltage stability.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The circuit autonomously measures its own bus connection resistance and automatically adjusts the termination resistance without requiring external intervention. The measuring circuit detects the actual resistance, the determination circuit calculates the required adjustment, and the system self-corrects the termination resistance, making the system self-regulating and reducing the need for additional complex control mechanisms.

Inventive Principle:
Principle #25Self-service

3Reliability

If resistance measurement and adjustment is performed continuously, then communication reliability is maintained, but processing time is consumed for measurements and calculations

Engineering Contradiction:
Improvecommunication reliabilityVSAvoidmeasurement and processing time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

Instead of continuous measurement and adjustment, the system performs resistance measurement and termination adjustment periodically at predetermined intervals. The measuring circuit measures resistance at specific time points, and the determination circuit updates the termination resistance setting periodically. This periodic approach maintains communication reliability while minimizing the time lost to measurement and processing operations.

Inventive Principle:
Principle #19Periodic action

Data Source

PatentEP3777049B1Circuit for a bus system and method for operating a circuit
Publication Date: 2024.09.04 ROBERT BOSCH GMBH
  • EP3777049B1 patent drawingFigure 1~2a
  • EP3777049B1 patent drawingFigure 2b~3
  • EP3777049B1 patent drawingFigure 4a~5

AI summary

The invention provides a circuit (100) for a bus system, wherein the circuit (100) comprises: a measuring circuit (101) which is designed in order to measure a first resistance value between two bus-side connections (106, 108) of the circuit (100); an ascertaining circuit (102) which is designed in order to ascertain a second resistance value depending on the first resistance value; and a resistance circuit (104) which is designed in order to set a resistor, which can be connected between the two bus-side connections (106, 108), to the second resistance value.