Start with frequency reach
The first filter is the band you need to cover, plus headroom. A source must reach your highest operating frequency with margin for harmonics work and future expansion. Berkeley Nucleonics sources span from kilohertz starting points up to 54 GHz, so the practical question is how high you truly need to go. Buying far more reach than the application requires raises cost without buying capability, while buying too little forces a second instrument later. Pick the top frequency first, then let the other decisions refine the choice within that band.
Output power and level control
Next, fix the power you need at the device under test, after cables, switches, and any attenuation. A receiver test wants clean low-level tones, sometimes well below -100 dBm, which calls for a step attenuator option. A component or amplifier test wants healthy drive, and a few models reach +25 dBm. Just as important as the maximum is level accuracy and resolution, since a leveling error propagates straight into every measurement made against the source.
Phase noise, switching speed, and channels
Three decisions usually settle the choice once the band and power are known. Phase noise sets spectral purity, and the source must be quieter than whatever it tests, with attention to the close-in region for radar and quantum work and the far-out region for wideband interference. Switching speed sets agility, and the right figure depends on your dwell or test budget, with fast and ultra-fast options available where it matters. Channel count decides whether one output suffices or whether you need phase-coherent multi-channel operation for beamforming, MIMO, or phased-array test. These topics each have a dedicated note linked at the close.
Modulation and form factor
Decide what the signal must do. If you only need clean tones, pulses, and sweeps, an analog source is the simpler and cleaner choice. If you need digital communications standards, arbitrary I/Q waveforms, or real-time pulse descriptor word playback for electronic warfare, a vector source is required. Finally, decide where it lives: a portable benchtop unit for the lab, a 1U or 2U rackmount for a test system, or a compact flange-mount module for embedding inside OEM equipment. Form factor often decides between two otherwise similar models.
Mapping families to use cases
Berkeley Nucleonics organizes its sources into three families. Signal generators are the broad analog instruments with touch-screen control. Synthesizers and sources are compact, agile modules optimized for low noise or fast switching, often for embedding or for multi-channel systems. Vector signal generators add I/Q and PDW capability for communications and EW. The table maps each family to the work it suits and links a representative datasheet.
| Family | Best for | Representative models | Datasheet |
|---|---|---|---|
| Signal Generators | General-purpose RF and microwave test, production verification, widest frequency reach, touch-screen benchtop or rack use | 870A (to 54 GHz), 855B (multi-channel, +25 dBm), 865B | 870A · 855B |
| Synthesizers & Sources | Low-noise local oscillators, fast-switching agile sources, compact and OEM-embedded modules, phase-coherent multi-channel systems | 865B-M (lowest close-in noise), 825-M (5 µs switching), 845-M, 805-M | 865B-M · 825-M |
| Vector Signal Generators | Digital communications standards, arbitrary I/Q waveforms, radar and EW emulation with real-time PDW playback | 875 (1 to 4 channels, 10 MHz to 40 GHz) | 875 |
A short worked example
Suppose you are building a four-channel phased-array radar test bench up to 20 GHz, you need phase-coherent outputs, and switching speed is critical for agile waveform emulation. Frequency reach rules out the lowest-band parts. Channel count and phase coherence point to the multi-channel synthesizers and to the multi-output 855B. Switching speed favors the 825-M with its fast control port and 5 microsecond option. If the same bench later needs to inject realistic modulated threats, a Model 875 joins it for the vector and PDW work. The decision falls out of the requirements in order, rather than from any single headline number.
Get a recommendation
The fastest path to the right source is a short conversation about your band, power, noise, agility, and channel needs. Berkeley Nucleonics application engineers will map those onto a specific model and option set. Contact info@berkeleynucleonics.com or call 800-234-7858. For deeper background, see the companion notes on phase noise and spectral purity, switching speed and agility, and vector modulation and PDWs, or browse the full RF & Microwave Signal Generators documentation page.