Frequency Plan
The Frequency Plan tells the analysis engine what frequency bands your design operates at. For chains with mixers, it resolves the frequencies at every stage automatically once you provide the RF band and at least one IF or LO value per mixer.
Where to find it
Frequency planning lives in two places:
| Location | What it shows |
|---|---|
| Freq Plan tab (header) | Dedicated full-screen workspace — RF entry, mixer stage cards, cascade summary, spectrum diagram |
| System Spec editor (System Specs bar) | Same RF fields and stage cards inline, with the spectrum diagram side-by-side |
Both surfaces edit the same plan. Use the Freq Plan tab for detailed work on multi-mixer chains.
RF entry
At the top of the frequency plan, enter the entry RF band:
| Field | Description |
|---|---|
| RF Center | Center frequency of the RF band (MHz or GHz) |
| RF Bandwidth | Channel bandwidth of the RF band |
These fields are always editable regardless of whether the chain has mixers.
Mixer stage cards
When the chain contains one or more mixers, a stage card appears for each mixer. You only need to enter one value — IF center or LO center. The other is derived automatically.
Entering frequencies
| You enter | System derives |
|---|---|
| IF Center | LO = RF ± IF (based on mixing side) |
| LO Center | IF = LO − RF or RF − LO (based on mixing side) |
Click into the IF or LO field, type a value, and press Enter or click away to commit. The derived value appears immediately.
Mixing side
Each stage card has a High / Low / Auto selector for the mixing side (whether LO is above or below RF):
| Option | Behavior |
|---|---|
| High | LO is above RF — use for high-side injection |
| Low | LO is below RF — use for low-side injection |
| Auto | System infers side from the entered LO vs. RF values |
Resolved state
Once frequencies are resolved, the stage card shows the derived value in a muted style alongside your entered value. If a value cannot be resolved, the field shows an unresolved indicator.
Cascade summary
When the chain has mixers, a cascade summary bar appears at the top of the frequency plan showing the resolved band at each stage, e.g.:
RF: 2440 MHz → IF: 140 MHz
Color coded:
- Blue — the anchor value (the one you entered)
- Gray — derived value
- Dashed gray — unresolved
Additional badges:
- Amber "N DOF" — degrees of freedom remaining (how many more values you need to enter)
- Red "N unresolved" — stages that could not be resolved
Multi-mixer chains
For chains with more than one mixer, from the second stage on, the previous stage's output is used as the current stage's input. You configure each mixer independently.
Example: 2-stage RX chain
RF: 2440 MHz
→ Mixer 1 (IF: 200 MHz, LO derived: 2640 MHz)
→ Mixer 2 (IF: 10.7 MHz, LO derived: 210.7 MHz)
If any stage is unresolved, all downstream stages are also shown as unresolved.
Frequency spectrum diagram
When frequencies are fully resolved, a spectrum diagram appears showing:
- RF and IF bands (colored regions)
- LO center frequency marker
- Image frequency location (RX mode)
- Harmonic markers (2×, 3×, ...) (TX mode)
In the System Spec editor, use the Show/Hide Sketch button to toggle the diagram. In the Freq Plan tab, the diagram fills the lower portion of the view automatically.
If any required band is missing, the diagram is not shown.
Warnings
The frequency planner surfaces three categories of warnings: global warnings about operating mode or an over-constrained plan (shown at the top of the Freq Plan view), per-mixer warnings on individual stage cards for issues like negative or conflicting frequencies, and informational notes when the system auto-selects a mixing side or detects image interference.