LVDS Transceiver Circuit for Extended Transmission Lengths

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Solution Overview

Problem

Existing Low Voltage Differential Signaling (LVDS) connections are limited by short line lengths and potential differences between modules with different power supplies, leading to errors and restricted data transmission paths.

Innovation Solution

The solution involves a transmitting/receiving device with a circuit arrangement that includes a second resistor between connection points and AC coupling means to improve signal settling and quality, allowing longer data transmission paths and accommodating different power supplies by forming transmission branches and using matching resistors and inductive transformers.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Length of stationary object

If the LVDS connection line length is extended beyond the conventional limit, then the data transmission path can be extended, but signal quality deteriorates and transmission errors increase

Engineering Contradiction:
Improvedata transmission path lengthVSAvoidsignal transmission reliability
Core Design Contradiction:
Length of stationary objectVSReliability

Solution Approach 1:

The patent introduces intermediate circuit components (first and second capacitors, first and second resistors) between the transmitter and receiver to mediate the signal transmission. These components form a filtering circuit that actively manages signal integrity over extended distances, allowing the data transmission path to exceed conventional LVDS length limits while maintaining reliable signal delivery.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Adaptability or versatility

If modules with different power supplies are connected via LVDS, then system versatility increases, but potential differences cause signal interference and transmission errors

Engineering Contradiction:
Improvecompatibility with different power suppliesVSAvoidpotential difference interference
Core Design Contradiction:
Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The patent employs AC coupling capacitors to isolate the DC potential differences between modules with different power supplies. By blocking DC components while allowing AC signal transmission, the circuit creates an equipotential reference for signal communication, eliminating potential difference interference and enabling versatile connections between modules with different power configurations.

Inventive Principle:
Principle #12Equipotentiality

3Length of stationary object

If the LVDS connection length is increased, then more modules can be connected, but signal settling time increases and transient responses are delayed

Engineering Contradiction:
Improveconnection lengthVSAvoidsignal settling time
Core Design Contradiction:
Length of stationary objectVSLoss of time

Solution Approach 1:

The patent incorporates RC filtering circuits (comprising capacitors and resistors) that act as signal conditioning stages before the signal reaches the receiver. These circuits preliminarily filter and stabilize the signal, reducing transient oscillations and accelerating settling time, thereby compensating for the increased propagation delay inherent in extended connection lengths.

Inventive Principle:
Principle #10Preliminary action

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 configuration enhances signal settling at the receiving unit, improves signal quality, and extends the length of LVDS connections beyond the conventional 1-meter limit, ensuring reliable data transmission even across modules with different power supplies.

Implementation Method 1

a first AC coupling means for coupling the longitudinal receive branches to the data transmission link is arranged in parallel with the second resistor

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

the second resistor is adapted as a matching resistor to a characteristic impedance of the lines of the data transmission link

Methodology Applied
Scientific EffectElectrical resistance: Electrical Resistance

Data Source

PatentEP2683124B1Transmission/reception device and use in an automation system
Publication Date: 2015.11.25 SIEMENS AG
  • EP2683124B1 patent drawingFigure 1~2
  • EP2683124B1 patent drawingFigure 3
  • EP2683124B1 patent drawingFigure 4

AI summary

The sending- and receiving device has a receiving longitudinal branch formed between a receiving unit (RX) and a terminal point, while another receiving longitudinal branch is formed the receiving unit and another terminal point. The capacitors (C1,C2) are arranged in the respective receiving longitudinal branches. A resistor (R1) is arranged between the capacitors and the receiving unit, such that the receiving longitudinal branches are connected to each other. Another resistor (R2) is arranged between the terminal points, and parallel to an alternating current coupling unit (6).