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circuitRF Quick Start

For engineers who already know circuit simulators. In a couple of pages: what circuitRF is, how it's organized, and how to run a simulation and see a plot.

What circuitRF is

circuitRF is a lightweight, cross-platform RF circuit simulator. If you've used a SPICE tool or a commercial RF/microwave EDA suite, you'll be at home — but the analyses and the workflow are built around the RF problem, not the time-domain transient problem. It is deliberately not a SPICE simulator.

Simulations available:

• DC — operating point (linear and nonlinear), the bias prerequisite for HB.

• S-parameters — linear multiport network parameters over a frequency sweep, with renormalization and embedded Touchstone (.sNp) blocks.

• Harmonic Balance (HB) — steady-state nonlinear analysis, single- and two-tone, with power/source continuation for convergence at drive. Reports Pout, gain, efficiency, PAE, spectra, intermodulation.

• Loadpull / sourcepull — a first-class experiment: sweep the source/load reflection coefficient over a Smith-chart grid and contour the figures of merit. Loadpull Pursuit automatically searches for the terminations that optimize a metric.

• Parametric sweeps — wrap any analysis in one or more swept variables (available power, a bias voltage, a frequency, any user variable).

Data Display: results plot on rectangular, Smith, and polar charts, and in tables. Measured data (Touchstone, .spl, .lpcwave) overlays simulated data on the same axes — a measured loadpull contour plots exactly like a simulated one.

How a project is organized

circuitRF is a hierarchical, cell-based tool (like the commercial RF suites, not like a flat SPICE deck). The pieces:

• Library — a collection of cells you can reuse and reference. circuitRF can reference several libraries at once.

• Cell — a reusable building block with up to three views: a Symbol (the glyph drawn when the cell is instanced, and where its ports sit), a Schematic (the electrical contents), and a Layout (the physical artwork, drawn against a technology and simulated by the planar method-of-moments solver). A cell declares parameters that an instance can override — this is how hierarchy passes values top-down.

• Hierarchy — a schematic can instance other cells as sub-cells. Push into a sub-cell to edit it, pop back out; an edit to a cell affects every instance.

• TestBench — the thing you actually simulate: a top schematic plus its analyses and measurements.

The workspace window

A workspace is a folder holding a .cws file and a folder per cell — membership is the filesystem, so the Project panel is showing you what is on disk. Open one and you get the window below: documents in tabs down the middle, tool panels docked around them.

Everything in it is movable. Drag a tab to reorder it, against an edge to split the area, or clear of the window to float it; drag a tool panel by its tab to re-dock it anywhere. View ▸ Hide Dockers (Ctrl/⌘+Shift+H) gives the whole window to the documents and back again, and View ▸ Reset Layout restores the arrangement you chose in Settings. The arrangement is saved into the .cws, so a workspace reopens the way you left it.

Region by region, panel by panel: The Workspace.

Build a schematic: components, wires, the pin grid

The short version is below. The editor in full — the Library Palette, every toolbar button, the context menu, and setting up the analysis that runs the circuit — is The Schematic Editor.

1. Place a component. Click a tile in the Library Palette (or drag it onto the canvas). A ghost follows the cursor; click to drop. The tool stays armed so you can place several. Press R to rotate the ghost, Esc to stop placing.
2. Wire it up. Press W (or the Wire button) and click from one pin to another. Enter or double-click finishes a wire; Esc cancels it.
3. Edit a value. Double-click a component's value label right on the schematic to edit it inline — type 50 Ω, 1.2 nH, 2 GHz and press Enter. (Double-clicking the body opens the full parameter editor.)

Pins vs. Ports vs. Terms

Three things sound similar but do different jobs. The distinction matters because it controls what becomes an external interface versus an excitation/measurement point:

The Reference Guide has a fuller treatment with diagrams; for Quick Start: use Term to define S-parameter ports on a test bench, and Pin to expose a reusable cell's connections.

Run a simulation

1. Open Simulate → Setup Analyses… (or the Analyses panel) and add an analysis (e.g. S-Parameter, 1–10 GHz). For an HB example, add Harmonic Balance and drive the input with a P1Tone (available-power) source.
2. Press Run ▶. circuitRF extracts a netlist from the schematic, elaborates it, and runs the analysis on a background thread.
3. The run writes results/<name>/run.npy. Open Data Displays that are already showing this result refresh automatically.

See the result on the Data Display

1. Open a Data Display (Ctrl/⌘+Shift+D) and add a plot — Rectangular, Smith, Polar, or Table.
2. In the trace card, pick the data source (your run), then the signal — e.g. S(2,1). On a rectangular plot choose a transform such as dB20; on a Smith chart the complex value plots directly.
3. For loadpull, choose the loadpull run and a contour metric (Pout, PAE). The optimum (max-power / max-efficiency) markers and interactive markers read values off the contour surface.

Headless / command line

The engine runs without the GUI — useful for scripting and batch sweeps. From a .cnl netlist (a human-readable circuit description):

$ circuitrf sparam mycircuit.cnl --freq 1GHz:3GHz:50MHz -o mycircuit.s2p

This reads the netlist, runs the S-parameter analysis, and writes a Touchstone file. (Make sure the circuit's port count matches the extension, or omit -o to let circuitRF name it .sNp automatically.)

Every analysis runs this way, not just S-parameters — dc, hb (harmonic balance), lp and lpp (loadpull and pursuit), and em, which runs an EM setup and writes the same files the Simulate button writes. Results go to stdout and progress to stderr, so a long run can be piped and watched at the same time. The full reference is The Command Line.