How Analysis Works
The analysis engine runs automatically whenever the chain or system spec changes. It traverses the signal path and computes cascade metrics at every stage.
Signal path extraction
The engine starts from the boundary source block and follows port connections in the direction of signal flow, until it reaches the boundary sink.
LO branches are identified and excluded: any block connected via an LO port to a mixer is treated as a support block and omitted from the cascade.
The result is an ordered list of blocks representing the main signal path.
Cascade computation
With the ordered path, the engine computes:
- Power propagation — input power flows left to right, adding each stage's gain
- Noise figure cascade — Friis formula applied stage by stage
- OIP3 cascade — recursive intercept formula applied stage by stage
- OP1dB cascade — same recursive formula as OIP3
- Headroom — margin between actual output power and P1dB/Psat at each stage
See Reference Equations for all formulas.
Compute states
Every output value carries one of three states:
| State | Meaning | Displayed as |
|---|---|---|
| COMPUTED | All prerequisites present | Value shown normally |
| PARTIAL | Some prerequisites missing | Value shown with ~ badge |
| UNKNOWN | Critical input absent | — or ? shown |
The tool never fills in UNKNOWN values with guesses. If a required parameter is missing, the affected metric and all metrics that depend on it are reported as UNKNOWN.
Why a metric might be UNKNOWN
The cascade is a dependency chain. A missing value stops propagation:
- Missing Gain on any block → power propagation stops at that block; all downstream absolute power levels are UNKNOWN
- Missing Noise Figure → NF cascade breaks; all downstream NF and sensitivity metrics are UNKNOWN
- Missing OIP3 (or IIP3) → OIP3 cascade breaks at that block
- Missing Input Power in system spec → all absolute power levels are UNKNOWN (but total gain and cascaded NF are still computed)
See Bottlenecks for how to identify and fix these.
Bypassed blocks
A block can be bypassed to exclude it from cascade analysis without removing it from the chain. Bypassed blocks are treated as a zero-gain passthrough:
- Gain contribution: 0 dB
- Noise figure contribution: none
- Linearity contribution: none (not included in OIP3/IP3 cascade)
The block stays on the canvas and its parameters are preserved. Toggle bypass on or off at any time — analysis updates immediately.
Bypass is useful for comparing analysis results with and without a specific stage, for example checking how much a lossy filter affects cascaded NF.
Analysis re-run triggers
Analysis re-runs after any:
- Parameter edit in the workbench
- System spec change
- Chain topology change (add/remove block, connect/disconnect)
- Undo/redo action
There is no manual run button — results are always live.