What is VSG?
A VSG (Vector Signal Generator) is a piece of electronic test equipment that generates digitally modulated RF signals for testing and measuring wireless devices and receivers. A VSG can produce complex modulation formats — including 5G NR, LTE, Wi-Fi, and custom waveforms — with precise control over frequency, power, modulation quality, and impairments. VSGs are fundamental instruments in 5G device development, conformance testing, and manufacturing.
How Does VSG Work?
A VSG consists of a digital baseband generator, digital-to-analog converters (DAC), up-conversion stages (IF and RF), power amplifiers, and output filtering. The baseband section generates the desired modulation waveform — either from stored waveform files or in real time from baseband parameters. The waveform is converted to analog, up-converted to the target RF frequency, and output at the specified power level. Modern VSGs support bandwidths up to 2 GHz for mmWave testing, carrier frequencies up to 54+ GHz, and can generate multi-carrier/multi-RAT signals. They can also add controlled impairments (noise, fading, frequency offset) to test receiver robustness. Key VSG specifications include output power range, frequency accuracy, EVM (residual), phase noise, and ACLR.
Use Cases
5G NR receiver sensitivity and selectivity testing, UE and base station conformance testing, production line RF testing, R&D receiver algorithm development, and multi-standard signal generation for lab testing.
3GPP / Standards Reference
3GPP TS 38.521 (NR UE conformance test setup), 3GPP TS 38.141 (NR BS conformance test setup), relevant IEEE/IEC instrument standards
Related Terms
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This glossary entry is part of the 5GWorldPro Complete 5G Glossary. To go deeper into 5G architecture and technology, explore our 5G Training courses.
