What should you know about RF signal generators?
RF signal generators provide calibrated test signals. Analog (CW) generators output sine waves with optional AM, FM, phase and pulse modulation; vector signal generators add an I/Q modulator and baseband arbitrary waveform generator for digital standards; arbitrary waveform generators and RF-DAC sources synthesize wideband signals directly. Key specifications are frequency range, output power and level accuracy, phase noise, harmonics and spurs, and modulation quality (EVM).[1]
How are generators used in receiver tests?
For sensitivity tests, the generator provides a modulated signal at a precisely known low level, often through attenuators to avoid leakage. For blocking and intermodulation tests, multiple generators are combined with isolators or hybrids, and their phase noise and broadband noise must not dominate the result.
Why does generator phase noise matter?
In reciprocal-mixing, blocking and adjacent-channel tests, the interferer generator’s phase noise at the wanted channel offset adds noise directly, so tests specify maximum generator noise.[2]
How are harmonics handled?
Generator harmonics (often −30 dBc or so) can corrupt harmonic or mixer measurements; external low-pass filters clean the signal. Reverse power protection prevents damage from transmitting DUTs.
Frequently asked questions
What is a VSG?
A vector signal generator with I/Q modulation and arbitrary baseband waveforms.
Why add an attenuator at the output?
To improve match and reduce leakage at very low levels.
What is level accuracy?
How close the output power is to the set value, typically within about ±1 dB or better.
See also
References
Online sources accessed October 21, 2026; printed works cited by edition. See all sources.
- “Fundamentals of Spectrum Analysis”. C. Rauscher, Rohde & Schwarz. 2001 and later editions.
- “RF Microelectronics, 2nd ed.”. B. Razavi, Prentice Hall. 2012.