Signal Integrity and EMI Fundamentals

Day 1

Fundamentals

• Electrical signals

• Maxwell vs. Kirchhoff: limits of circuit theory

• Decibel and logarithmic scales

• Spectrum of a signal: time domain vs. frequency domain

• Resonance

• Quality factor (Q), loaded and unloaded

• Bandwidth

• Impedance matching definition

• Frequency vs. dimensions (size)

• Time vs. distance

• Scattering parameters (s-parameters)

• Typical formats and how to measure them

 

High-speed/frequency effects in electronic circuits: When a capacitor is an inductor

• High speed and RF effects

• Skin effect, return current and parasitic effects

• The importance of rise time and fall times

• Controlling signal return currents, differential vs. common mode currents

• Introduction

• Non ideal components

• The "hidden schematic" concept

• Digital and high speed circuit key parameters

• Wires

• Cables and connections basics

• PCB structures

• Transmission lines basics

• Lumped vs. distributed systems

• Vias

• Shielding basics

• Clocks

 

Transmission Lines: Controlling Propagation

• Wiring and connecting components: Limitations of high-frequency and high-speed systems

• What is a transmission line?

• Motivation: Signal propagation

• Modelling a transmission line – Characteristic impedance – Velocity of propagation

• Description of typical transmission lines – coax, pairs, microstrip and stripline

• Reflection coefficient

• Standing wave ratio (SWR, VSWR and ISWR) and Return loss

• Matching: Avoiding Reflections, Obtaining Maximum Power Transfer

• Maximum transfer of power and avoiding reflections

• Matching with LC components

• Matching networks: L, PI and T networks

• Matching in narrow and broadband networks

• Matching with transformers

• Matching with transmission lines

• Terminations to avoid SI/EMI problems: Solutions and techniques

• Using software to design a matching network

 

Day 2
 

Signal Integrity Parameters

• What is Signal Integrity (SI) in electronic circuits?

• Undesired effects

• Propagation time and delay

• Reflections and ringing

• Inductive vs. capacitive coupling: Crosstalk (near and far)

• Delays

• Jitter

• Ground bounce

• Power supply noise

• High frequency, dv/dt and di/dt

 

Grounding

• Signal ground vs. safety ground

• Ground in high frequency/speed applications – low impedance path

• Minimising ground impedance

• Common impedance

• Ground strategies (single point, multipoint, and hybrid)

• Ground loops

 

Filtering

• Basic ideas

• Filters for known impedances (no EMI applications)

• Basic design techniques

• Filters for EMI/EMC

• How filters work: Reflection vs. dissipation

• Insertion losses

• Source and load influence

• Parasitic and location effects

• Filtering with ferrites

• Saturation and undesired coupling effects

• Decoupling and bypass fundamentals

• Damping resonances and ringing

• Three terminal and feed through components

 

Printed Circuit Boards (PCBs)

• Basic ideas

• Design strategy

• Partitioning and critical zones

• PCB structures

• Choosing the PCB structure

• Power planes design and distribution

• Layout and routing (1, 2 and multilayer) techniques

• Ground planes

• Splits or ground discontinuities in planes

• Decoupling and bypass

• Crosstalk and guards

• How ground plane layout affects crosstalk

• Mixed signal PCBs (A/D designs)

• Controlling clock waveform

• Clock distribution

• Clock shielding

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Day 3

Cables

• Basic ideas for cable fundamentals

• The control of return current

• Types of cables – wires, twisted pairs, coax, shielded cables, ribbon cables,tc.

• Cable impedance

• Shielded cables and cable grounding

• Connectors – Parasitics in connectors for high-speed signals

• Avoiding crosstalk and reflections in cables (layout and terminations)

• Avoiding common impedance in cables

• Reducing emissions and pick-up in cables

Measuring and Troubleshooting Techniques

• Antenna basics

• How to measure EMI and SI effects – tools, instruments and techniques

• Scope and probe limitations

• Review of typical errors in measurement techniques

• Measuring high-frequency current in electronic circuits

• Diagnostic and troubleshooting techniques and hints

• Locating EMI sources with near field probes

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