Bottlenecks and warnings
- Bottleneck means part of the analysis cannot propagate correctly
- Warning means the analysis did propagate, but the stage may be operating too close to a limit
Bottlenecks
A bottleneck is a block that prevents part of the analysis from propagating downstream.
The bottleneck list is narrower than the broader idea of an UNKNOWN metric:
- A bottleneck entry is currently raised when missing gain stops power propagation through the chain
- Other missing values such as NF or IP3 can still make downstream metrics UNKNOWN, but they do not currently appear as formal bottleneck list entries
What counts as a bottleneck
| Condition | Current behavior |
|---|---|
| Missing gain on a stage | The stage is marked as a bottleneck, power propagation stops, and downstream absolute power values become UNKNOWN |
| Missing input power (Pin) | Absolute power levels can remain UNKNOWN, but this is not currently emitted as a formal bottleneck list item |
| Missing NF / IIP3 / OIP3 / P1dB | Related analysis results may remain UNKNOWN, but these are not currently emitted as formal bottleneck list items |
What the panel shows
The Analysis panel exposes three related concepts:
- Bottlenecks in the Bottlenecks, Warnings & Frequency Notes section
- Warnings for headroom-related issues
- UNKNOWN or PARTIAL metric states directly in the stage table and summary values
If a stage is a true bottleneck, SigChain highlights it and shows it in the bottleneck list.
If a metric is UNKNOWN for some other reason, you may see UNKNOWN values in the tables without seeing a formal bottleneck entry.
How to fix a bottleneck
Option 1 — Enter the value manually: Click the block column in the Parameters workbench, find the missing field, and type in the value.
Option 2 — Ask the AI:
Set the mixer noise figure to 7 dB
Option 3 — Link a component from the library: Find the component in the library search and link it to the block. Its datasheet parameters are imported automatically.
Warnings
Warnings are the platform's way of saying: "This stage is still analyzable, but it is getting too close to a limit."
In SigChain, warnings are driven by the configured P1dB Backoff Margin setting in System Specs. A stage is flagged when a computed margin falls below that threshold.
Warning types shown today
| Warning type | Meaning |
|---|---|
| P1dB Margin warning | Input/output operating level is too close to the stage's 1 dB compression point |
| Psat Margin warning | Output power is too close to the stage's saturation power |
| Max Input Margin warning | Input power is too close to or beyond the stage's maximum allowed input |
Where warnings appear
- In the Bottlenecks & Warnings card inside the findings section
- In the Stage Table as highlighted columns and warning icons
How to interpret them
- A positive margin means the stage is still below the limit
- A small positive margin means the stage is getting close
- A negative margin means the stage is beyond the limit
Warnings are not proof that the chain is unusable, but they are a strong signal to review gain distribution, drive level, and stage limits before relying on the design.
How to reduce warnings
Common fixes include:
- lower the drive into the flagged stage
- redistribute gain across earlier and later stages
- choose a block with higher P1dB, Psat, or max-input capability
- adjust the P1dB Backoff Margin threshold to match your application's real linearity requirement
Partial vs. UNKNOWN
PARTIAL means the tool has enough information to make a best-effort estimate, but some inputs are missing. Treat PARTIAL values as directionally correct but not reliable for sign-off.
UNKNOWN means the computation cannot proceed at all. There is no estimate.