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What is Crosstalk?
2018.04.19
Points of this article
・Crosstalk occurs between parallel wires.
・The causes of crosstalk are capacitive (electrostatic) coupling due to stray (parasitic) capacitance, and inductive (electromagnetic) coupling due to mutual inductance.
In succession to the previous section on “Differential (Normal) Mode Noise and Common Mode Noise”, this time crosstalk is explained.
Crosstalk
Crosstalk is the transmission of signals and noise due to coupling between lines, and is also called interference. The term “crosstalk” itself is evocative of the age of analog telephony, and of “talking across lines”. If two wires are separate (including the thin film wiring on a PCB), then electrical signals and noise should not propagate between them, but if two lines are parallel, in particular, the stray (parasitic) capacitance and mutual inductance that exists between the two lines results in noise transmission. Hence crosstalk is regarded as inductive noise.
Coupling between lines can be capacitive (electrostatic) coupling due to the stray (parasitic) capacitance, or can be inductive (electromagnetic) coupling resulting from the mutual inductance. As a result of these, noise is induced. The following are illustrations of the two types of coupling and the simplest equivalent circuits in each case.
In both cases, equations are indicated for the noise voltage Vn that occurs in nearby wiring pattern 2 due to noise in wiring pattern 1, which is a nearby noise source. R is the resistance component, C is capacitance, M is mutual inductance, Vs is the noise source voltage, and Is is the noise source current.
Here, it should be understood that crosstalk occurs across parallel wires. It should also be noted that when the wires are perpendicular, the stray capacitance and mutual inductance are much smaller.
【Download Documents】 Elementary EMC for Circuit Designers Working on EMC Issues
This handbook is designed to give designers who are going to work on EMC an idea of what EMC is. It promotes a sensible understanding of the relationship between EMC and the three perspectives of semiconductor devices, product specifications, and circuits and boards.
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Electrical Circuit Design
- Soldering Techniques and Solder Types
- Seven Tools for Soldering
- Seven Techniques for Printed Circuit Board Reworking
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Basic Alternating Current (AC)
- AC Circuits: Alternating Current, Waveforms, and Formulas
- Complex Numbers in AC Circuit
- Electrical Reactance
- What is Impedance? AC Circuit Analysis and Design
- Impedance Measurement: How to Choose Methods and Improve Accuracy
- Impedance Matching: Why It Matters for Power Transfer and Signal Reflections
- Resonant Circuits: Resonant Frequency and Q Factor
- RLC Circuit: Series and Parallel, Applied circuits
- What is AC Power? Active Power, Reactive Power, Apparent Power
- Power Factor: Calculation and Efficiency Improvement
- What is PFC?
- Boundary Current Mode (BCM) PFC: Examples of Efficiency Improvement Using Diodes
- Continuous Current Mode (CCM) PFC: Examples of Efficiency Improvement Using Diode
- LED Illumination Circuits：Example of Efficiency Improvement and Noise Reduction Using MOSFETs
- PFC Circuits for Air Conditioners：Example of Efficiency Improvement Using MOSFETs and Diodes
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Basic Direct Current (DC)
- Ohm’s Law: Voltage, Current, and Resistance
- Electric Current and Voltage in DC Circuits
- Kirchhoff’s Circuit Laws
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- Thevenin’s Theorem: DC Circuit Analysis
- Norton’s Theorem: Equivalent Circuit Analysis
- What Is the Superposition Theorem?
- What Is the Δ–Y Transformation (Y–Δ Transformation)?
- Voltage Divider Circuit
- Current Divider and the Current Divider Rule
Thermal design
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About Thermal Design
- Changes in Engineering Trends and Thermal Design
- A Mutual Understanding of Thermal Design
- Fundamentals of Thermal Resistance and Heat Dissipation: About Thermal Resistance
- Fundamentals of Thermal Resistance and Heat Dissipation: Heat Transmission and Heat Dissipation Paths
- Fundamentals of Thermal Resistance and Heat Dissipation : Thermal Resistance in Conduction
- Fundamentals of Thermal Resistance and Heat Dissipation : Thermal Resistance in Convection
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- Thermal Resistance Data: JEDEC Standards, Thermal Resistance Measurement Environments, and Circuit Boards
- Thermal Resistance Data: Actual Data Example
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- Thermal Resistance Data: θJA and ΨJT in Estimation of TJ: Part 1
- Thermal Resistance Data: θJA and ΨJT in Estimation of TJ: Part 2
- Surface Temperature Measurements: Methods for Fastening Thermocouples
- Surface Temperature Measurements: Thermocouple Mounting Position
- Surface Temperature Measurements: Treatment of Thermocouple Tips
- Surface Temperature Measurements: Influence of the Thermocouple
- Estimating TJ: Basic Calculation Equations
- Estimating TJ: Calculation Example Using θJA
- Estimating TJ: Calculation Example Using ΨJT
- Estimating TJ: Calculation Example Using Transient Thermal Resistance
- Estimation of Heat Dissipation Area in Surface Mounting and Points to be Noted
- Surface Temperature Measurements: Thermocouple Types
- Summary
- Collection of Important Points Relating to Thermal Design
Switching Noise
- Procedures in Noise Countermeasures
- What is EMC?
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Dealing with Noise Using Capacitors
- Understanding the Frequency Characteristics of Capacitors, Relative to ESR and ESL
- Measures to Address Noise Using Capacitors
- Effective Use of Decoupling (Bypass) Capacitors Point 1
- Effective Use of Decoupling Capacitors Point 2
- Effective Use of Decoupling Capacitors, Other Matters to be Noted
- Effective Use of Decoupling Capacitors, Summary
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Dealing with Noise Using Inductors
- Frequency-Impedance Characteristics of Inductors and Determination of Inductor’s Resonance Frequency
- Basic Characteristics of Ferrite Beads and Inductors and Noise Countermeasures Using Them
- Dealing with Noise Using Common Mode Filters
- Points to be Noted: Crosstalk and Noise from GND Lines
- Summary of Dealing with Noise Using Inductors
- Other Noise Countermeasures
- Basics of EMC – Summary
Simulation
- Thermal Simulation of PTC Heaters
- Thermal Simulation of Linear Regulators
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Foundations of Electronic Circuit Simulation Introduction
- About SPICE
- SPICE Simulators and SPICE Models
- Types of SPICE simulation: DC Analysis, AC Analysis, Transient Analysis
- Types of SPICE simulation: Monte Carlo
- Convergence Properties and Stability of SPICE Simulations
- Types of SPICE Model
- SPICE Device Models: Diode Example–Part 1
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- SPICE Subcircuit Models: MOSFET Example―Part 1
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- SPICE Subcircuit Models: Models Using Mathematical Expressions
- About Thermal Models
- About Thermal Dynamic Model
- Summary
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About the ROHM Solution Simulator
- How to Access the ROHM Solution Simulator
- Trying Out the ROHM Solution Simulator (1)
- Trying Out the ROHM Solution Simulator (2)
- Starting a Simulation Circuit in the ROHM Solution Simulator
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- Exporting Circuit Data to PartQuest™ Explorer
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- Optimization of PFC Circuits
- Optimization of Inverter Circuits
- About Thermal Simulations of DC-DC Converters
- Circuit-Theory-Based Design Simulation