Go to www.awrcorp.com
Back to search page Click to download printable version of this guide.

VSS Modeling Guide

NI AWR Design Environment v14.03 Edition

1960 E. Grand Avenue, Suite 430
El SegundoCA 90245
Phone: +1 310.726.3000
Fax: +1 310.726.3005
Website: www.ni.com/awr

U.S. Technical Support phone: 888.349.7610


© 2019 National Instruments. All rights reserved. © 2019 AWR Corporation. All rights reserved.


  • Analog Office, APLAC, AWR, AWR Design Environment, AXIEM, Microwave Office, National Instruments, NI, ni.com and TX-Line are registered trademarks of National Instruments. Visual System Simulator (VSS), Analyst, and AWR Connected are trademarks of AWR Corporation/National Instruments. Refer to the Trademarks section at ni.com/trademarks for other National Instruments trademarks.

  • Other product and company names mentioned herein are trademarks or trade names of their respective companies.


For patents covering NI AWR software products/technology, refer to ni.com/patents.

The information in this guide is believed to be accurate. However, no responsibility or liability is assumed by National Instruments for its use.

Table of Contents

1. Simulation Basics
1.1. Additional Documentation
1.2. Typographical Conventions
1.3. Basic Concepts
1.3.1. RF Budget Analysis and RF Inspector Simulations
1.3.2. Time Domain Simulations
1.3.3. Sweeping Simulations
Design Parameters
Controlling Sweeps
Swept Measurements
1.4. Data Signals
1.4.1. Digital Signals
1.4.2. Analog Signals
1.4.3. Complex Envelope Signals
Working with Complex Envelope Signals
Center Frequency Of Zero
Other Benefits and Limitations
RF Budget Analysis Simulations
1.4.4. Sampling Frequencies, Data Rates and Oversampling
Sampling Theory and Aliasing
Selecting A Sampling Frequency
Signal Bandwidth
1.4.5. Generic Signals
1.4.6. Fixed-Point Signals
1.4.7. Signal Properties
1.4.8. Primary Data Path
1.5. Automatic Configuration
1.6. Spectral Analysis in Time Domain Simulations
1.6.1. Fourier Transforms
1.6.2. Averaging, Windowing and Power Spectrum Estimation
1.6.3. Frequency Resolution and Video Bandwidth
1.6.4. Negative Complex Envelope Frequencies
1.6.5. Measuring Channel Power
1.7. Microwave Office Schematics: Parameterized Subcircuits and Sweeping
1.7.1. Passing Parameters from Microwave Office Circuits
1.7.2. Using a Microwave Office Circuit Swept Parameter in a System Diagram
1.8. References
2. RF Modeling in VSS
2.1. RF Blocks In VSS
2.1.1. Linear Filters
2.1.2. Amplifiers
2.1.3. Mixers
2.1.4. Miscellaneous Blocks
2.1.5. Working with Non-RF Blocks
2.2. RF Budget Analysis
2.2.1. Simulation Frequencies
2.2.2. Computed Values
2.2.3. Measurement Output
2.2.4. Nonlinear Modeling
Saturation Effects
S12 Limitations
2.2.5. Thermal Noise Modeling
2.2.6. Phase Noise Modeling
2.2.7. Additional Information
2.3. RF Inspector
2.3.1. Indicating IM Products
2.3.2. RF Inspector Dialog Box
Details Section
Heritage Window
Signal Classification
Other Features
2.3.3. Modulated Signals
CW and Modulated Signal Display
2.3.4. Performance Considerations
Frequency Settings
Noise Floor
Component Limits
Simulation Convergence
2.3.5. How RFI Works
2.3.6. Feedback Loops in RFI
2.3.7. Additional Notes
Saturation Effects
S12 Limitations
Additional Hints and Tips
2.4. Bi-directional RF Blocks
2.5. Impedance Mismatch Modeling
2.5.1. VSWR Parameters
2.5.2. Block Support for Impedance Mismatch Modeling
2.5.3. Time Domain Modeling Basics
Determining Impedances
Voltage Corrections
2.5.4. Source and Load Impedances
2.5.5. Interfacing to Non-RF Blocks
2.5.6. Additional Notes
Feedback Loops
2.6. Temperature Dependent Parameters of RF Blocks
2.6.1. RF Blocks that Support Temperature Dependence
2.6.2. Piecewise Interpolation Support
2.6.3. Frequency Dependency Support
2.7. Time Domain Filter Considerations
2.7.1. FIR Filters
Frequency Sampling
Windowed FIR Filters
Windowed FIR + Allpass IIR Filter
Other FIR Design Techniques
2.7.2. IIR Filters
2.7.3. Working With Circuit Filter Based Blocks
2.8. Time Domain Nonlinear Modeling Issues
2.8.1. Aliasing
2.8.2. Saturation Effects
2.9. NI Technical Data Management Streaming (TDMS) File Format
2.9.1. Analog Waveforms
2.9.2. Digital Waveforms
3. Noise Modeling in VSS
3.1. Modeling Noise in VSS
3.2. Circuit Noise
3.2.1. Linear RF Blocks
3.2.2. Amplifiers
3.2.3. Mixers
3.2.4. Additional Notes
Combining Signals with Ambient Noise
3.3. Channel Noise
3.4. Phase Noise
3.4.1. Phase Noise in RF Budget Analysis
3.4.2. Phase Noise in Time Domain Simulations
Generating Phase Noise
Measuring Phase Noise
3.5. SNR, Eb/N0 and Es/N0
3.5.1. SNR
3.5.2. Eb/N0 and Es/N0
3.6. Noise and Negative Frequency Folding
4. VSS Modeling Hints and Tips
4.1. RF Budget Analysis Simulations
4.1.1. Signal Simulations
4.1.2. Block Simulations
4.1.3. Phase Noise Simulations
4.1.4. Thermal Noise Simulations
4.1.5. RF Budget Analysis Paths
4.2. RF Inspector Simulations
4.3. Differences Between RF Budget Analysis and RF Inspector Simulations
4.4. Time Domain Simulations
4.5. Phased Arrays and MIMO Arrays
4.5.2. Building from Blocks
4.5.3. Additional Phased Array/MIMO Antenna Array Tips
4.6. Miscellaneous

Please send email to awr.support@ni.com if you would like to provide feedback on this article. Please make sure to include the article link in the email.

Legal and Trademark Notice