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Decide whether the task is selection or frequency separation

Draw the common port and each branch. For every operating condition, state which signals may be present and which paths should conduct. If one path is selected at a time by a control signal, the task differs from simultaneously combining signals in separate frequency bands.

Identify whether a component performs additional functions such as filtering, termination or transmit/receive protection. A product name may emphasize only one of these. Use the actual block diagram and data sheet to establish behavior rather than relying on the word multiplexer alone.

The diplexer, triplexer and duplexer guide explains frequency and transmit/receive terminology. Keep that architecture decision separate from the later PCB placement and control review. Choosing the correct family of function prevents a detailed layout from implementing the wrong signal-routing task.

RF path state record

Build a port-state matrix

For each state, record enabled paths, disabled paths, expected terminations and allowed input signals. Include startup, shutdown and transitions where relevant to the component. A schematic showing only the normal steady state can omit important operating conditions.

Check control levels and timing against the selected device. Determine whether signals may be applied during switching and what the documentation requires. Do not infer power-handling or sequencing behavior from a pin count or an apparently similar part.

Retain the state matrix with test software and firmware. A change in the controlling code can alter RF behavior without changing copper or the BOM. The manufacturing test must reproduce the intended states rather than relying on undocumented defaults.

Port isolation allocation

Allocate isolation at a defined victim boundary

Identify the aggressor power, victim tolerance and the frequency or bandwidth relevant to the interaction. Keep the same reference conventions when comparing them. A noise-like signal, a tone and a transient may require different treatment even if they share a dBm label.

The worksheet calculates the source-to-allowed-level difference, adds an entered planning margin, and subtracts separately established isolation. It reports both the signed remainder and the nonnegative additional allocation. An excess already provided by the design is kept visible rather than being disguised as a new requirement.

For a teaching case, a 20 dBm aggressor, a minus 50 dBm allowed level, 6 dB planning margin and 40 dB existing isolation leave 36 dB to allocate. This is not a universal receiver requirement or component guarantee. Real coupling, compression and frequency-selective behavior need their own analysis and measurement.

Evaluate loss and matching alongside isolation

A path with high nominal isolation may still have unacceptable insertion loss or mismatch in the wanted state. Record all relevant passband and stop-state properties over the required frequency range. Do not optimize a single number while hiding its effect on the useful signal.

Check the specified terminations and normalization of the data. An unused branch that is open in the product may not reproduce a measurement made with a matched termination. Keep port loading and external circuitry in the model boundary so the comparison is physically meaningful.

Use the RF component handoff guide to organize model files, port numbering and package transitions. It is particularly useful when combining a vendor component model with board extraction, where an omitted or double-counted launch can distort the apparent result.

Review physical coupling and control routing

Place sensitive and high-power paths with a clear understanding of their return conductors and coupling opportunities. Spacing, parallel length, reference continuity, package geometry and enclosure connections can matter. No universal gap guarantees the system isolation allocation.

Include supply and control paths in the review. A disabled RF branch can still be affected by coupling through other connections or by a state transition. Identify how bias and switching activity appear in the intended operating modes and how they will be tested.

If shielding or additional filtering is proposed, define the mechanism it is intended to address and verify the complete installed arrangement. A temporary laboratory shield can be a useful diagnostic, but its dimensions, contacts and mechanical integration need a producible specification before release.

Characterize the required states and measurement floor

Define the port pairs, control states, power levels and frequencies for the measurement. Calibrate the relevant reference planes and retain correction information. A setup with insufficient dynamic range can only establish a bound on isolation, not an arbitrarily precise large number.

Measure wanted-path transmission and unwanted-path coupling under compatible conditions. Include any state or loading condition that is relevant to the product. Do not keep only the state with the strongest isolation or the frequency with the lowest loss.

Where nonlinear behavior matters, use an appropriate test at the intended operating point. The IMD3 procedure explains why source residuals and analyzer distortion must be separated from the DUT. A small-signal S-parameter result cannot establish every high-level or switching condition.

Release the routing function and evidence together

Keep part identity, port map, state matrix, firmware configuration and PCB revision in the same release package. Mark alternatives requiring review. A device with the same number of ports can still differ in termination behavior, control logic or acceptable signal conditions.

Specify assembly and test scope for the quotation. Identify which states are screened in production and which are covered by engineering characterization. A reduced production test needs a demonstrated relationship to the faults and requirements it is intended to address.

Send 吃瓜tv current files, quantity and the specific construction or test question. The worksheet can produce an optional local isolation-allocation record for manual attachment. It does not approve the component or transfer its data automatically to the enquiry form.

Review transient and unused states too

A port-state table should show more than the preferred operating path. Identify startup, inactive branches and transitions that matter to the selected device. Record permitted signals and termination behavior using the actual documentation.

Test the relevant states with suitable power and dynamic range. If the measurement only establishes an isolation lower bound, retain that wording. An unresolvable low-level trace does not justify assigning additional digits to a component or board rating.