circuitRF Reference Guide

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File Formats

circuitRF stores a project as a folder of small, human-readable, text files — diffable and version-control friendly. The core idea: the **schematic** (what you draw) is the source of truth; the **netlist** (what the engine runs) is derived from it.

Schematic vs. netlist

Two complementary artifacts, related one way at the engine boundary:

  .csch  (schematic: placement, wires, labels, canvas objects, view state)
     │  net extraction  — headless, deterministic
     ▼
  design model  ≡  what a .cnl represents
     │
     ▼
  engine → DataSet (results)

A hand-authored .cnl with no .csch is fine — it simulates, it just has no drawing to edit visually until you draw one.

The file family at a glance

ExtensionWhat it is
.cschSchematic view — placement, wires, labels, canvas objects, analyses, measurements.
.csymSymbol view — a cell's glyph: drawing primitives + pins mapped to ports. See the Symbol Editor.
.ccellCell manifest — the cell's declared parameters + defaults, which view is primary per type, and the IsTestBench flag.
.clayLayout view — the cell's physical geometry: shapes on layers, instances, PCell placements, bitmaps, the display unit and the snap grid. A real, first-class view; see The Layout Editor.
.cddData Display config — placed plots/tables/contours, their binding to a run's results, markers, view state.
.cnlNetlist — the engine's input (derived from a schematic, or hand-authored).
.cwsWorkspace config — the top-level "what am I working on" document. References libraries, known files, the default technology and assembly rules, and any other projects or kits this one uses.
.cwsuserYour own view of a workspace — the panel arrangement, which tabs were open, which tree categories you expanded, and the colour theme. Sits beside the .cws. Optional, personal, and safe to delete; see Your own view of a workspace.
.clibLibrary manifest — name, version, metadata (cells are discovered by scanning, not listed here).
.ccolorColor theme — a named light+dark palette for rendering.
.ctechTechnology — the layer table (GDSII layer/datatype pairs, colours, purposes), the substrate stackup with each conductor's resistive films, the DRC rules, and the default display unit and snap grid. Shared at workspace level: every layout in the workspace resolves against one of these. See Technology.
.cmatMaterial library — named materials (εr, tanδ, μr, σ₂₀, α₂₀, the thermal conductivity, density and specific heat, σ(T) and k(T) tables, and where each value comes from) in exactly the form a technology's own Materials list takes. A technology names its libraries, relative to the .ctech; several technologies may share one. It opens as its own document, and is also edited from the technology editor's Materials tab. circuitRF ships generic-materials.cmat, and New Workspace copies it beside the technology. See Materials.
.c3d3D view — a cell's solid model: boxes, prisms, cylinders, sheets, polyhedra, bond wires, the kernel operations below, placed cells, ports, face boundaries, VARs and any number of embedded EM setups. See The 3D Editor and The 3D view's operations.
.cemEM setup — one electromagnetic run's configuration: which layout, the stackup mapping, the ports and their reference impedances, the mesh settings, the frequency plan and the de-embedding choice. See EM Setup.
.charmharmonicaRF document — the DUT, the source and load termination planes at every harmonic, the package, the display configuration and the markers. See harmonicaRF.
.wBondwBond design — bondwire geometry: the wires, their arrays and profiles, the substrate and the solver settings. Self-contained and shareable. See wBond.
.crailrailRF document — the rails, their sources, loads and reference, the parts and the part library they resolve against, the target and the band. See railRF.
.cmodelComposed FET model — a nonlinear transistor model placed as a ComposedFET: its extrinsic network, its current and charge constituents, the finger count and gate width it was measured at, the temperatures it is valid at, its symbol and where it came from. A ZIP holding a readable model.json and any arrays as .npy. See Writing a .cmodel.
.cmcModel Composer document — the data a model is built from and the conditions it was measured under, from which a .cmodel is exported. JSON text; its data stays in the files it names, with a cache beside it in <name>.cmc-cache/. See The Model Composer document.
.cchainRF chain budget — a receive chain's system inputs (frequency, bandwidth, input power, source temperature, required SNR, any blockers) and its stages in signal order, each a System block or a composed stage with the part's own parameters as text. JSON. See RF Chain Budget.
.csmithSmith Chart document — a generator impedance over frequency and an ordered cascade of two-pin elements, plus what the chart is normalized to, the overlays, the markers and the constant-Q setting. Numbers are in base SI. See Smith Chart.

These are circuitRF's own formats. The interchange formats it reads and writes — GDSII, DXF, Gerber plus Excellon drill, and .kicad_pcb board files — are not in this family and are not documents you open: they are imported into cells, or exported from them. See Interchange for what each carries and what it cannot. IPC-2581 (.xml, .cvg) is the same kind of thing and is import only; it imports one step of the file, known by its root element whatever the file is called. See IPC-2581. The same goes for STEP (.step, .stp), the solid-model interchange format: its parts are imported into a 3D view, and a 3D view or a layout is exported as one — see The 3D Editor ▸ STEP.

Results are not documents either. A run writes .npy (see .npy export), and the Data Display, circuitrf read and circuitrf plot read .npy, Touchstone .sNp, the loadpull .spl and .lpcwave, and binary simulation datasets (.ds): blocks of nested sweeps, read as one group per block named after its analysis (SP1), each variable a cube on the block's sweep axes. Only a full grid is read. Export Data and a run verb's -o out.ds write one. Try circuitrf read sweep.ds.

Touchstone is read and written in its 1.x form; a Touchstone 2 file with keyword blocks is refused with the reader's reason. A two-port's noise block (frequency, NFmin in dB, |Γopt|, ∠Γopt, rn normalised to the option line's R) is read, and an S-parameter block uses it. It is also written: a two-port S-parameter run with Noise=yes writes its noise parameters as that block after the data.

Which of these are documents you open

.csch, .csym, .clay, .cdd, .ctech, .cem, .charm, .wBond, .crail and .csmith each open as a tab in the workspace. .ccell, .clib, .cws and .cwsuser are manifests the application maintains for you — though double-clicking either half of a workspace opens the whole workspace. .cnl is the engine's input and is normally derived rather than edited.

A layout's review state

A .clay carries the Layout Review's state beside the artwork, and both keys are left out of the file until there is something to say:

Key Holds
Review Target, "Mmic" when the layout is reviewed as a die (absent: a board); Disabled, the ids of the checks turned off; and Thresholds, each threshold changed from its default, keyed <check>.<threshold> ("edge-copper.pullback": 300000) — a length in the layout's database units, an area in mm² (whatever unit it is shown in), a number of substrate heights and a count as the number itself. A threshold set back to its default is removed. A check or threshold id this version does not know is kept as it is.
ReviewAcceptances The findings accepted, each with Key, CheckId, Reason (required), AcceptedUtc, LayerName and Summary (the finding's sentence when it was accepted). Key is <check>\|<layer>/<datatype>\|<minX>,<minY>,<maxX>,<maxY>: the check, the finding's layer and its marker's bounding box in database units, exactly as circuitrf review --json reports it. Moving the marked copper changes the key, and the acceptance is then listed as stale.

The 3D view's operations

A .c3d holds four kinds of object that the geometry kernel (OpenCASCADE, which ships inside circuitRF) builds rather than the editor. circuitrf reference 3d-view prints every field; these are the rules a hand-written or scripted file must follow.

$type What it is Its operands
Boolean Op — Subtract, Unite or Intersect — of one Blank and one or more Tools. KeepTools (Subtract only) also keeps each Tool as a solid of its own, right after the result. Blank, Tools
Fillet The named Edges of its Target rounded by Radius. Target
Chamfer The named Edges of its Target cut by Distance (and Distance2 along the edge's second face). Target
Step One solid part of a STEP file in the cell's 3d/ folder: File, Part (its occurrence path in the file's assembly, 1/2), Hash, the file's Unit, and the SourcePath it was imported from. none

The composed FET model

A .cmodel is a ZIP container. model.json is the model itself, readable as text; arrays/<name>.npy holds any array it needs (a table, a network's weights), in circuitRF's own .npy layout. It holds the extrinsic network, the four constituents Id, Ig, Qg and Qd (each an equation, a table or an ANN), the periphery and temperatures it describes, and optionally self-heating, traps and dispersion. The Model Composer writes it, and so can a script of your own: Writing a .cmodel gives every field, the arrays' layout, and complete Python and MATLAB scripts. circuitrf check reads a .cmodel and names the field of anything it refuses.

The Model Composer document

A .cmc is JSON text. It names the data a model is built from and the conditions each set was measured under; it never holds the data itself. Numbers are in base SI — volts, amps, seconds, ohms, hertz — except temperatures, in °C.

Field What it holds
FormatVersion 1. A file from a newer circuitRF is refused, saying so.
Kind Active (a FET) or Passive (an N-port).
BasePeriphery Fingers and UnitWidth ("125 um") of the measured device. Active only.
DataSets Each with a Name, a Kind, its Sources, its Conditions, its Import settings and any Exclusions.
Pads How the probe pads are removed — see below. Absent when the data is at the device plane.
Network The six-pin extrinsic network and its variables' settings — see below. Absent when the data is intrinsic.
Steps Each model step's settings and result: Current, Charge, Thermal and Traps below. A step not described here is kept as written.
Panels Hidden: the window panels switched off. Absent when every panel shows.

A data set's Kind is DcIv, PulsedIv, SParams (CW multi-bias), PulsedSParams, SimulatedTables (currents and Y, S or C on a bias grid, from another simulator), LargeSignal (validation only) or PassiveSParams. Its Sources are paths relative to the .cmc.

Conditions field What it holds
AmbientC The chuck temperature, °C.
ReferencePlane Where the bias voltages were measured: instrument, probe, device or intrinsic. BiasPathOhms (Gate, Drain, Source) goes with instrument.
PulseWidth, Period, SampleDelay Pulsed sets: the pulse, its repetition and when in the pulse the sample is taken, in seconds.
Quiescent Pulsed sets: Vgs, Vds and optionally Ig, Id of the bias the pulses start from.
PrePulse Double-pulse sets: Vgs, Vds, Width, Gap (from its end to the measuring pulse) and optionally Id. A pre-pulse whose current dissipates is a warning: its heating is not modelled.
TrapState Pulsed sets: auto, setting or extreme.
SoakTime, Compliance, Note The soak before measuring, the instrument's current limits (Gate, Drain, in A) and a note.

Import says how the sources were read, so a re-import is exact:

Exclusions lists the points left out of every fit — Point, a point's id, and the Reason. A Touchstone point's id is its file; a CSV row's is <file>:<line>; an array point's is <file>#<index>.

Pads has a Kind and the files that kind needs, relative to the .cmc:

A pad file must cover the data's frequencies; one that does not is refused, naming both ranges.

Network holds:

Field What it holds
Schematic The network, a .csch with exactly six pins: 1, 2, 3 the extrinsic gate, drain and source, 4, 5, 6 the intrinsic ones. Its VAR block's variables are its element values.
Variables Per variable: Min, Max, Lock (true holds it at its value), Tie (To another variable, times Factor), Scaling (fixed, perFinger or perFingerInverse) and Value, the value in use in base SI — typed and locked for a fixed value, or written by a fit. Absent: the schematic's own value.
FlatnessBand [low, high] in Hz: the band the frequency flatness of the intrinsic elements is measured over. Absent: 1/10 to 1/2 of the data's highest frequency.
Fit How the network is fitted — see below. Every field is optional.
Result What the last fit found: Method, Cost, per fitted variable its StdError, Spread across the starts and AtBound (Min or Max), the Report lines, and a Digest of the values. Written by the fit.

Fit holds:

Field What it holds
Method MultiBias (the default), ColdFet, or ColdFetThenMultiBias — the cold-FET values as the start of the multi-bias fit.
PinchOff, Forward The cold points, each { "Set", "Point" }. Absent: chosen at Vds = 0 V — the lowest Vgs that is pinched off, and the highest with the gate conducting. A cold-FET method without one stops, naming the bias it needs.
ForwardVariant Extreme (the default: the device collapsed to a node by strong forward gate current) or Moderate (a gentler forward bias, with the channel resistance).
ChannelResistance Ω, for Moderate: the channel resistance, from another test structure.
ColdBand [low, high] in Hz for the cold points. Absent: every frequency.
Active The active points of the multi-bias fit, a list of { "Set", "Point" }. Absent: one off, one on, one near the knee and one in saturation, chosen from the data and written here after a fit.
Weights Flatness (1), Cold (1) and SmallSignal (0): the frequency flatness of the intrinsic elements at the active points, the cold-FET models at the cold points, and S against a fitted small-signal circuit.
Starts, Seed, Algorithm, Budget The global search: 4 seeded starts (seed 1) of cmaes or de, each spending Budget evaluations (200 per variable) before a gradient polish. The same seed gives the same values.
PoorRelativeError, PoorCorrelation A value whose relative error exceeds the first (0.2), or whose correlation with another exceeds the second (0.95), is reported as poorly determined, with a lock or a tie suggested.

R, L and C values stay at or above zero by default, a mutual's coupling stays below 1, and a value that ends on a bound is reported as at that bound.

A stock network — GaN two-shell, classic single shell or series only — is copied beside the .cmc when chosen and is then an ordinary schematic. An R, L, C or mutual value starts with Min 0 and Max 100 times its starting value.

Steps.Current is the drain and gate currents' step: Settings, the Result of the last fit, and Network, a digest of the network values the fit was made through (a later network fit makes it stale). Settings holds:

Field What it holds
DataSets The I–V sets to fit to. Absent: every DcIv, PulsedIv and SimulatedTables set. If pulsed they must share one Quiescent and PrePulse, unless Traps models trapping; a mix is refused, naming what differs. With traps each point takes the trap state Steps.Traps maps it to, as further inputs of Id. At two or more temperatures the currents take the temperature T as an input: each point at its chuck temperature, a DC point at its junction temperature when Thermal models self-heating.
Id, Ig Each Method (ANN, the default, Table or Equation) and that method's settings: Hidden ([8, 8]), Activation and MaxIterations (6000) for a network; GridStep (0.1 V), Regrid (ANN, or RBF through the points themselves), Smoothing and, with T an input, TemperatureStep (25 °C, which needs Regrid: ANN) and with traps TrapStep (1 V) for a table; Template or the user's own Expression (Id) or IgGs and IgGd (Ig), with Parameters (Value, Min, Max, Lock each), TemperatureCoefficients (template parameters made linear in T; absent is the template's current scale with data at two or more temperatures, [] is none) and Algorithm (cmaes, de or lm) for an equation. The templates are Angelov, CurticeQuadratic, CurticeCubic, Statz and Materka for Id, and Diode for Ig.
IdFloor 0.1: Id is fitted to each point's own value down to this fraction of the largest current, and to that floor below it.
IgFloor 1e-4: Ig is fitted to the same ratio everywhere above this fraction of the largest gate current (I0 of its Transform).
GateSplit Sign (the default): at vds ≥ 0 a forward gate current is the gate–source branch and a reverse one the gate–drain branch, the other way round at vds < 0. GateSource or GateDrain puts all of it in one branch.
Symmetry Exchange: fit vds ≥ 0 only, for a model with drain–source symmetry.
SmallestSwing 0.05 V: a table whose step is more than twice this warns that low-level intermodulation is unreliable.
Seed, Restarts, HeldOutFraction 1, 3 and 0.1: the same seed gives the same model; each network is trained from that many starts; that fraction of the points, spread over the domain, is never trained on and reports the error.
Dispersion Present to fit IdRF: Tau (1e-6 s), DataSets (absent: every S-parameter set), Reference ([vgs, vds] where IdRF equals Id; absent: the S point nearest the middle) and Hidden.

Result holds the fitted constituents exactly as the .cmodel will (Constituents), their Gx, Tau, and Arrays — the name of the cache file holding their arrays — then per current the training and held-out RMS error, absolute and relative to the range (Errors), Conductance (the fitted Gm and Gds against the data's own DC derivatives), Symmetry (with Exchange: the value, slope and gate jumps at vds = 0), Eq649 (the share of the RF conductances no single current reproduces), Reference, with traps the Traps block exactly as the .cmodel will carry it and DcIv (the DC I–V's RMS error at its DC trap states: Count, Rms, Relative), and the Report lines.

Steps.Charge is the gate and drain charges' step, with the same three fields. The charges are fitted to the intrinsic capacitances of the S-parameter sets, averaged over the FlatnessBand. A document with no S data has none to fit: the step writes Linear charges from Typed instead. Settings holds:

Field What it holds
DataSets The S-parameter sets to fit to. Absent: every set with S data. One trap state, as for the currents, unless Traps models trapping: then an ANN Qd takes the trap states when pulsed S-parameters give each a level, and Qg never does. At two or more temperatures an ANN charge takes T as an input; any other method is fitted temperature-independent.
Qg, Qd Each Method (ANN, the default, Table or Equation) and that method's settings: Hidden ([8, 8]), Activation and MaxIterations (3000) for a network, trained on the charge's two capacitances; GridStep (0.1 V), Interpolant (ANN, or RBF through the points themselves), Path (A, B or Mean, the default) and Smoothing for a table integrated from the capacitances; Template (Depletion, Angelov or Linear) or the user's own Expression, with Parameters and Algorithm, for an equation.
Anchor [vgs, vds] where both charges are zero. Absent: [0, 0], or the data point nearest it when it lies outside the data.
FlatnessLimit 0.1: a point whose C11 or C22 varies across the band by more than this fraction of its mean counts for less.
Seed, Restarts, HeldOutFraction 1, 3 and 0.1, as for the currents.
Drift Present to fit the drift decomposition instead of Qg and Qd's methods: Lambda (0), VdsZero (0.05 V — the points this close to vds = 0 fit the depletion charges), Hidden and MaxIterations. Needs the current step: the drift charge reads its Id.
Typed Constant capacitances in farads for a document with no S data: Cgs, Cgd, Cds and Cm, each 0 when absent. Cgs, Cgd and Cds are never negative; Cm, a transcapacitance, may be. A datasheet gives Cgd = Crss, Cgs = Ciss − Crss and Cds = Coss − Crss. They become C11 = Cgs + Cgd, C12 = −Cgd, C21 = Cm − Cgd and C22 = Cds + Cgd of the Linear charges. Absent with no S data: all four are 0. Present beside S data: the step refuses, since typing would discard the data.

Result holds Constituents (Qg and Qd exactly as the .cmodel will), Arrays, Anchor, Errors (per capacitance C11, C12, C21, C22: the RMS error of the fitted charge's derivative, and that as a fraction of the capacitance's range), PathDifference (a table's two integration paths' RMS difference as a fraction of the charge's range), CdsSpread (with Drift: how much Cds varies across vgs at a fixed vds, which QDS cannot follow), with a trapped Qd the Traps block, Points (the number of S biases the charges were fitted to), Typed (the four capacitances the charges were written from, when there was no S data), and the Report lines.

Steps.Thermal is temperature and self-heating: Settings and the Result of the last run. With the data at one temperature the model is valid at that temperature only and self-heating is unavailable. Settings holds:

Field What it holds
SelfHeating true to give the model a thermal node, and to put each DC point at its junction temperature. Needs two or more temperatures.
Rth A typed thermal resistance in °C/W. Absent: extracted from pulsed I–V at two or more chuck temperatures and DC I–V at the same biases.
RthModel Constant (the default) or Linear: an extracted thermal resistance that varies linearly with the ambient.
Cth, TauTh, Ladder, FitTau At most one: a thermal capacitance in J/°C; a thermal time constant in s; a ladder of { "Fraction", "Tau" } poles whose fractions of Rth add up to 1; or true to fit the time constant to the low-frequency roll-off of the S data's Re Y22, which is refused while traps are modelled.
PulsedSets, DcSets The sets the extraction reads. Absent: every PulsedIv set whose quiescent bias dissipates nothing, and every DcIv set.
MinPower 0.1: DC points dissipating less than this fraction of the largest DC power are left out of the extraction.
Isothermal How the isothermal drain current is built, with the same fields as the current step's Id. Absent: the current step's own.
TauSets The S-parameter sets FitTau reads. Absent: every SParams set.

Result holds Temperatures (the data's), Rth, RthSlope and Tref, RthSource (Extracted or Typed), Poles (the thermal network's Rth and Cth, absent until its dynamics are set), TauTh, Extraction (the fit's residual in K and relative to the temperature rise, the points used, those left out for low power and those unresolved, and the vgs, vds and power ranges of the points used), TauFit and the Report lines.

Steps.Traps is trapping: Settings and the Result of the last run. The Trained coupling needs pulsed I–V; the Shift coupling does not, and maps no data to trap states. A pulsed set's trap state is set by its PrePulse level when it has one, else its Quiescent bias. A point pulsed toward that bias — no lower in vgs for gate-lag, no higher in vds for drain-lag — is at that bias's trap state; one pulsed beyond it is placed by the set's TrapState: auto (the default) uses it to check the model only, setting puts it at the bias's trap state, extreme at the pulse's own. DC points are at their DC state. A state trained from one trap level is used with a warning; one with none cannot be enabled. Settings holds:

Field What it holds
Model None (the default), CaptureEmission or Custom.
Coupling Trained (the default) or Shift. Under Shift the current step fits a trap-free Id to the DC I–V and this step fits the strengths.
States The enabled states. Absent: drain-lag (phi2) for CaptureEmission, every state with expressions for Custom.
Emission Constant (the default) or ThermallyActivated, which needs each enabled state's Ea. CaptureEmission only.
Parameters The model's parameters, as the .cmodel names them. Absent ones take their defaults: capture 10 ns, emission 1 ms, Xref 1 V, Vc 50 mV, Tref 25 °C. Under Shift, a ShiftDrain or ShiftGate here is typed and is not fitted.
Expressions Custom: per state, { "Dynamics": …, "Dc": … }.
DcIv Target (the default): the DC I–V trains the model. Validation: it is held out, and only checks it.

Result holds Levels (per state, the trap-setting levels in the data, V), Beyond (per state, the pulsed points beyond their bias used only to check the model) and the Report lines. Under Shift it holds Coupling: "Shift", Strengths (per strength, { "Value", "Error" } in V/V; a typed strength has no Error) and Residual (Points, the number of S biases fitted, and Gm and Gds, the RMS residuals in S of gm_RF = (1 − ShiftGate)·gm and gds_RF = gds + ShiftDrain·gm) instead of Levels and Beyond.

Steps.Passive is a Passive document's model: Settings and the Result of the last fit. Settings holds:

Field What it holds
Set The passive data set. Absent: the document's only one.
Block The block one fit reads, by its source. Absent: the set's only one. Not with Family.
Topology A library topology — series-rlc, parallel-rlc, inductor-skin, capacitor-esr-esl, resistor-parasitics, pi, tee, bond-wire, via, spiral, mim, tline-pads — or a .csch relative to the .cmc whose pins 1…N are the ports.
Variables Per variable Min, Max, Lock, Tie and Value, as the network block has them. Bounds default to 0 … 1000× the starting value.
Fit Weighting (Uniform, or Band with Band in Hz and Emphasis, default 10), Starts (2), Seed (1), Algorithm (cmaes or de), Budget, ProposalBudget (40 per variable), PoorRelativeError (0.2), PoorCorrelation (0.95).
Family Fit every block as one model over a geometry: Geometry (the parameter's name, e.g. turns), Form (Auto, Constant, Linear, Quadratic, Cubic or Rational), Monotone, HeldOut (the geometry checked and not trained on; absent: the middle one).
Export Cell, Library (a folder relative to the .cmc) and an optional Symbol (.csym); absent symbol: a box with N pins.

Result holds the Topology, the fitted Values (base SI), Cost, RmsDeltaS and Aic, a family's laws (Family: the geometry's range, the held-out geometry and its |ΔS|, and per variable its Form and Coefficients in the normalised geometry (g − Mid)/Half), and the Report lines. The exported cell's parameters are the variables, defaulting to the fitted values; a family's are the geometry first and every element as an expression of it, with a warning when a schematic sets the geometry outside the range the family was fitted over.

The data read from the sources is cached in <name>.cmc-cache/. When a source changes it is read again; when one goes missing the cached copy is used, with a warning. A step's arrays are cached there too, and a missing one is fitted again. The cache can be deleted at any time. circuitrf check reads a .cmc and names the field of anything it refuses.

Workspace › Library › Cell

The conceptual hierarchy maps to folders of the small files above — never one monolithic blob.

Cell = a folder of views

<CellName>/
   .ccell              manifest: parameters + defaults + primary view per type + IsTestBench
   schematic/  *.csch  schematic views
   symbol/     *.csym  symbol views
   layout/     *.clay  layout views

A cell need not have every view. A view sub-folder with exactly one file makes that file primary by default; .ccell records the primary when there are several. A placed component references its cell by relative path and resolves its glyph through the cell's primary symbol — so a broken path shows a "Not Found" glyph, and a resolved cell with a missing primary symbol shows a plain-rectangle stand-in. The cell folder is the unit you copy to share or reuse a cell.

Library = a folder of cells

<LibraryName>/
   .clib               manifest: name, version, metadata
   <CellA>/  …
   <CellB>/  …

Membership is filesystem-is-truth — the Project Tree discovers cells by scanning, so the .clib stays lightweight (no cell index). The standard component libraries ship in this shape. File → Add Library points the workspace at an external library folder.

Workspace = the project that references the above

A workspace is a folder (its name = the folder name) containing a .cws file. Membership is the filesystem; the .cws records configuration only: referenced libraries, "Known Files" bookmarks, the default technology and assembly rules, and the other projects and kits this one uses. It references, never embeds — the same cell or library can be used by multiple workspaces.

A workspace that references a vendor part library lists it under VendorLibraries, by name and folder; the key is absent when there are none:

"VendorLibraries": [ { "Name": "Caps", "Path": "/home/you/libraries/caps" } ]

A placed part names its file as vendorlib://Caps/<file inside the library>, so moving the library is one edit to Path.

Beside it sits a second, optional file: the .cwsuser, which is yours rather than the project's.

Your own view of a workspace

The .cwsuser holds the things that describe your afternoon rather than the design: where you put the panels, which tabs were open and which one was in front, which categories of the Project Tree you had expanded, and which colour theme you were using. Nothing in it affects a simulation, a schematic or a layout.

Three things follow, and all three are deliberate:

Double-clicking either the .cws or the .cwsuser opens the whole workspace — they are two halves of one thing. A .cwsuser on its own, with no .cws beside it, is not a workspace, and circuitRF says so rather than opening an empty window.

What makes a TestBench

A TestBench is not a separate file type — it is a cell whose schematic carries analyses and measurements, making it runnable. "TestBench" is a role, marked by the IsTestBench flag in the cell's .ccell, which the Project Tree uses to show it as runnable. A testbench is authored, saved, and version-controlled exactly like any other cell.

Port numbers are 1-based for you, positional in the netlist

Everything you see — symbol pins, dialogs, error messages — numbers ports from 1 (a VNA has port 1 and port 2, never port 0). The .cnl doesn't list port numbers at all: a component line names its nets in terminal order, and the engine infers the port from position. Net extraction emits nets in the symbol's terminal order — the one seam where the two conventions meet, and a tested one.

The generated netlist.cnl

The GUI does not keep per-cell .cnl files. When you simulate a TestBench, extraction writes a single netlist.cnl to the workspace root and the engine runs it. It is:

It is a generated scratch artifact, not part of the saved project — the .csch is the source of truth.

Shared rules

See also: Netlist format · Grid & Connectivity · Symbol Editor. Full design: docs/design/project-file-formats.md.