Spectrum Analyzer Basics: RBW, Noise Floor, and Buying Used Equipment

Why RBW and noise floor define analyzer usefulness

When buying a spectrum analyzer, especially used — two specs matter more than most:

• Resolution Bandwidth (RBW)
• Noise floor

These determine whether you can:

• resolve closely spaced signals
• detect weak emissions
• perform meaningful RF analysis

Understanding these specs prevents expensive mistakes.

Resolution Bandwidth (RBW): signal separation power

RBW defines the analyzer’s ability to distinguish signals close in frequency.

Narrow RBW:

• better signal separation
• lower displayed noise floor
• slower sweep times

Wide RBW:

• faster scans
• reduced frequency resolution
• higher noise floor

Why RBW matters in semiconductor environments

Narrow RBW is critical for:

• oscillator phase noise analysis
• spurious signal detection
• EMI troubleshooting
• PLL evaluation

Without sufficient RBW control, weak signals disappear into noise.

Noise floor: detecting the invisible

Noise floor defines the lowest detectable signal.

Lower noise floor = better sensitivity.

Factors affecting noise floor:

• internal design
• RBW settings
• preamp presence
• instrument age and calibration

RBW vs sweep time tradeoff

A key reality:

• narrower RBW increases sweep time

Engineers must balance:

• measurement speed
• resolution needs

For production environments, this tradeoff is critical.

Buying used spectrum analyzers: what matters most

1. RBW range

Ensure the analyzer supports:

• sufficiently narrow RBW for your application

2. Noise floor condition

Older analyzers may:

• drift
• require calibration
• have degraded front-end components

3. Preamp functionality

Built-in preamps improve sensitivity but must be tested.

4. Frequency range

Verify:

• coverage for your band of interest
• future-proofing needs

Explore our inventory.

Common used analyzer pitfalls

• worn RF connectors
• calibration drift
• noisy displays
• fan failures

Professional refurbishment reduces these risks.

FAQ

Is RBW more important than frequency range?
It depends on application. For weak signal detection, RBW is often more critical.

Can calibration fix noise floor issues?
Sometimes, but hardware degradation can limit recovery.

Tell HiTechTrader your frequency range and minimum signal levels. We can help you source spectrum analyzers with the RBW and sensitivity needed for semiconductor testing. Click here to contact HiTechTrader.