matlab-model-rf

name	matlab-model-rf
description	RF Toolbox and RF Blockset in MATLAB -- S-parameter I/O, network conversions (S/Z/Y/ABCD/T/H/G, mixed-mode), cascade/de-embedding, rfbudget analysis, circuit composition, matching networks, amplifier stability, mixer spurs, rational fitting, SI channels, baseband processing, Circuit Envelope simulation. Trigger: sparameters, Touchstone, .s2p, .s4p, rfplot, smithplot, rfparam, rfwrite, zparameters, yparameters, abcdparameters, s2sdd, cascadesparams, deembedsparams, rfbudget, noise figure, OIP3, IIP3, amplifier, modulator, nport, rffilter, attenuator, seriesRLC, shuntRLC, lcladder, txline, circuit, setports, clone, matchingnetwork, stabilityk, stabilitymu, powergain, gammams, gammaml, mixerIMT, OpenIF, rational, rationalfit, stepresp, txlineWRLGC, rf.Amplifier, rf.Mixer, rf.Filter, rf.Sparameter, rfsystem, RF Blockset.
license	https://www.mathworks.com/content/dam/mathworks/license/pmrl/license.md
metadata	{"author":"MathWorks","version":"1.0"}

RF Toolbox and RF Blockset

Design, analyze, and simulate RF systems in MATLAB -- from measured S-parameter data through full time-domain Circuit Envelope simulation. One unified workflow covering passive networks, active device characterization, system cascade budgets, and behavioral time-domain modeling.

When to Use

Measured data workflows

• Loading Touchstone files (.s1p through .snp), validating quality (passivity, causality, IEEE P370)
• Plotting on Smith charts and rectangular plots, interpolating, re-referencing impedance
• Converting between S, Z, Y, ABCD, T, H, G parameters; computing mixed-mode differential
• Cascading and de-embedding S-parameter networks; fixture removal

System design and analysis

• Building RF signal chains from behavioral elements (amplifier, modulator, rffilter, nport, etc.)
• Computing cascaded gain, noise figure, IP3, SNR, output power with rfbudget
• Comparing Friis vs Harmonic Balance solver accuracy
• Exporting to RF Blockset Simulink models, Communications Toolbox, or MATLAB scripts

Circuit-level design

• Composing arbitrary RF circuits with node wiring (SPICE-like netlist)
• Designing impedance matching networks (L, Pi, Tee topologies, Richards stubs)
• Analyzing amplifier stability (K-factor, mu), power gain, and matching conditions
• Mixer intermodulation analysis and spur-free IF frequency planning

Time-domain and signal integrity

• Fitting S-parameters to rational models; computing TDR, impulse, step responses
• Exporting broadband circuit models to SPICE or Verilog-A
• Building SI channel models from nport blocks, lossy transmission lines, and parasitics
• Processing complex baseband signals through rf.Amplifier, rf.Mixer, rf.Filter System Objects
• Full Circuit Envelope time-domain simulation via rfsystem (no Simulink knowledge required)

When NOT to Use

• Antenna design and radiation patterns -- use Antenna Toolbox
• RF propagation modeling (path loss, fading, ray tracing) -- use Communications Toolbox or Phased Array System Toolbox
• SerDes/high-speed serial link equalization (FFE, CTLE, DFE, IBIS-AMI) -- use SerDes Toolbox
• Radar waveform design or phased arrays -- use Phased Array System Toolbox

Must-Follow Rules

These apply across ALL RF Toolbox workflows. Violating them produces silent errors or blocks execution.

Universal

1. rfwrite blocks on existing files -- Always pass 'ForceOverwrite', true. Without it, MATLAB opens an interactive overwrite dialog that halts unattended execution.
2. Elements cannot be reused -- The same element object cannot appear twice in an rfbudget or circuit. Use clone(element) for independent copies.
3. Element Name must be a valid MATLAB identifier -- No spaces, no special characters. Use 'IFAmp' not 'IF Amp'.
4. Use tiledlayout/nexttile -- Not subplot. For all multi-panel figures.
5. rfparam returns complex, not dB -- Always use 20*log10(abs(rfparam(...))) for dB magnitude.

S-Parameters and Network Parameters

6. sparameters(filename, Z0) is invalid -- Cannot pass reference impedance at load time. Load first, then newref(s, Z0).
7. rfinterp1 interpolates real/imag independently -- Not magnitude and angle. Can produce artifacts near sharp resonances.
8. Frequency alignment required for cascade/de-embed -- cascadesparams and deembedsparams require identical frequency vectors. Always rfinterp1 to a common grid first.
9. deembedsparams always requires 3 arguments -- (sMeasured, sFixture1, sFixture2). For one-sided, pass an ideal thru for the unused side.
10. Mixed-mode port ordering is the #1 error source -- s2sdd option 1 (default) treats ports 1,2 as positive and 3,4 as negative. Verify which option matches your VNA port numbering.
11. snp2smp argument order: ports before impedance -- snp2smp(s, portList, Z0), not snp2smp(s, Z0, portList).

rfbudget and Elements

12. SignalBandwidth is required -- The 4th positional arg to rfbudget. Without it, NF/IP3/SNR remain empty.
13. Passive NF equals loss -- For rfelement, NF should equal abs(Gain). Prefer attenuator which handles this automatically.
14. nport Name is positional -- nport('file.s2p', 'MyName'), not name-value syntax.
15. rffilter: ResponseType is shape, FilterType is algorithm -- rffilter('FilterType', 'Bandpass') errors. Use rffilter('ResponseType', 'Bandpass').
16. show(b) opens a GUI -- Produces no command-window output. Use properties (b.TransducerGain, b.NF) for programmatic access.

Circuit Composition

17. setports/setterminals can only be called once -- Plan topology before defining terminals.
18. 2-port RF elements use 4-node mapping -- add(ckt, [in out inRef outRef], elem) for amplifier, modulator, nport, all txline types. Primitive 2-terminal elements (resistor, capacitor, inductor) use 2-node mapping.
19. Primitive constructors are positional -- resistor(100, 'R1'), not resistor('Resistance', 100).
20. setterminals takes a node vector -- setterminals(ckt, [1 2]), not setterminals(ckt, 1, 2).
21. All txline constructors use name-value pairs only -- No positional arguments.

Amplifier Analysis

22. powergain gain type string must be last -- powergain(s, 50, 50, 'Gt'), not powergain(s, 'Gt', 50, 50).
23. powergain returns linear, not dB -- Convert with 10*log10(g) (power gain uses 10x, not 20x).
24. Gmag returns NaN when conditionally stable -- Use Gmsg at frequencies where K < 1.

Rational Fitting

25. rational vs rationalfit -- Use rational for new code (AAA). Use rationalfit only for delay extraction.
26. Single-param fit returns plain vectors; multi-port returns cell arrays -- Always check with iscell(result).
27. freqresp takes Hz -- Not rad/s. Pass s.Frequencies directly.

System Objects (rf.*)

28. rf.Amplifier/rf.Mixer use 1-ohm power -- Vin = sqrt(Pin_W). This differs from rfsystem which uses 50-ohm.
29. rf.Filter frequencies are ABSOLUTE RF -- PassFreq_bp=[2.395e9 2.405e9] means absolute GHz. Not baseband offsets.
30. Properties locked during use -- Call release(obj) before modifying Nontunable properties.

rfsystem

31. Requires rfbudget -- rfsystem takes an rfbudget, not raw elements.
32. close_system needs save flag -- Use close_system(rfs, 0) to discard changes.
33. IdealizedBaseband only supports amplifier/modulator/rffilter/nport -- Other elements require CircuitEnvelope.

Workflow Quick Reference

Task	Entry Point	Details
Load/plot S-parameters	sparameters, rfplot, smithplot	reference/sparameters-io.md
Convert S/Z/Y/ABCD, mixed-mode	zparameters, s2sdd, snp2smp	reference/network-conversions.md
Cascade or de-embed networks	cascadesparams, deembedsparams	reference/cascade-deembed.md
Create rfbudget elements	amplifier, modulator, rffilter, etc.	reference/rfbudget-elements.md
Run cascade budget analysis	rfbudget, rfplot(b, 'Pout')	reference/rfbudget-analysis.md
Compose RF circuits	circuit, add, setports	reference/circuit-composition.md
Design matching networks	matchingnetwork, richards	reference/matching-networks.md
Analyze amplifier stability/gain	stabilityk, powergain, gammams	reference/amplifier-analysis.md
Mixer spurs and IF planning	mixerIMT, OpenIF	reference/mixer-analysis.md
Fit rational models, TDR	rational, stepresp, generateSPICE	reference/rational-fitting.md
Build SI channel models	nport + txlineWRLGC + circuit	reference/si-channel-modeling.md

Conventions

Code Style

• Use tiledlayout/nexttile for multi-panel figures (not subplot)
• Always label axes with units (GHz, dB, ns, dBm) and include figure titles
• Name elements descriptively for readable topology ('LNA', 'DCBlock', 'PCBTrace')
• Use clone() liberally for element reuse

Script-First Workflow

For design, analysis, or sweep tasks -- write code to .m files on disk, not inline snippets. For quick one-off checks, inline evaluate_matlab_code is fine.

Modern APIs

• tiledlayout/nexttile instead of subplot
• datetime instead of datenum
• rational instead of rationalfit (unless delay extraction needed)
• smithplot instead of smith
• rfplot for S-parameter visualization (handles dB conversion automatically)

References

Load the relevant reference file before writing code for a specific workflow. Each reference contains correct calling conventions, constructor arguments, property names, gotchas, and executable code patterns.

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Copyright 2026 The MathWorks, Inc.

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