Design by Finding RF Interference Analysis with Altium

RF interference analysis has become increasingly critical in modern electronic design as devices become more compact and operating frequencies continue to rise. Altium Designer provides powerful tools for identifying and mitigating RF interference issues during the PCB design process. This comprehensive guide explores the features, methodologies, and best practices for conducting RF interference analysis using Altium Designer.

Understanding RF Interference in PCB Design

Types of RF Interference

Common Sources Table

Critical Design Parameters

Key Factors for RF Analysis

Altium's RF Analysis Tools

EMI Analyzer Features

Tool Capabilities

• Near-field EMI prediction
• Resonance detection
• Current density analysis
• Radiation pattern visualization
• Coupling assessment

Analysis Methods

Available Analysis Types Table

Setting Up RF Analysis in Altium

Project Configuration

Essential Setup Steps

1. Layer stack definition
2. Material properties assignment
3. Net classes creation
4. Design rules establishment
5. Analysis regions definition

Configuration Parameters Table

RF Analysis Workflow

Pre-Analysis Steps

Preparation Checklist

1. Design rule verification
2. Net classification
3. Component placement review
4. Layer stack optimization
5. Analysis region definition

Analysis Execution

Process Steps Table

Interpreting Results

Key Metrics

Analysis Output Parameters

Result Visualization

Available Views

• Heat maps
• Current distribution
• Field patterns
• Frequency response
• Time domain reflectometry

Mitigation Strategies

Common Issues and Solutions Table

Best Practices

Design Guidelines

Layout Considerations

1. Critical trace routing
2. Stack-up optimization
3. Shield placement
4. Ground plane design
5. Component placement

Documentation Requirements

Essential Documentation Table

Frequently Asked Questions

Q1: How do I determine the appropriate analysis frequency range for my design?

A1: The analysis frequency range should be determined based on several factors:

• Highest operating frequency in the design (usually up to the 5th harmonic)
• Known susceptible frequency bands
• Regulatory requirements
• Clock frequencies and their harmonics
• Interface speeds and their harmonics Start with a broad sweep and then focus on problematic frequency ranges identified during initial analysis.

Q2: What are the most critical settings for accurate RF interference analysis in Altium?

A2: The most critical settings include:

• Mesh size (typically λ/10 to λ/20 at highest frequency)
• Boundary conditions (radiation boundary for emissions)
• Material properties (especially dielectric constants and loss tangents)
• Source definitions (proper port impedances and excitations)
• Monitor point placement (at areas of interest and regulatory test points)

Q3: How can I optimize the analysis time while maintaining accuracy?

A3: Several strategies can help optimize analysis time:

• Use symmetry planes when possible
• Start with coarse mesh for initial analysis
• Focus on specific frequency bands of interest
• Utilize design partitioning for large boards
• Enable GPU acceleration if available Balance these optimizations against accuracy requirements for your specific design.

Q4: What are the key indicators of potential RF interference issues in the analysis results?

A4: Key indicators include:

• Field strength peaks above expected levels
• Resonant frequencies near operating frequencies
• High current densities in unexpected areas
• Strong coupling between unrelated nets
• Standing wave patterns on transmission lines Monitor these indicators during analysis to identify potential problems early.

Q5: How should I prioritize RF interference issues identified in the analysis?

A5: Prioritize issues based on:

• Severity of the interference (field strength/coupling level)
• Frequency of occurrence
• Impact on critical functions
• Ease of mitigation
• Regulatory compliance requirements Create a prioritized action plan addressing the most critical issues first.