Advanced wireless communications systems are driving increasingly complex performance requirements and standards, reflected in each generation of mobile devices, base stations, satellites and electromagnetic spectrum operations (EMSO). Design and test challenges include wider bandwidth, higher frequency, complex modulation and multiple antenna systems.
To address these challenges, Keysight’s M9484C VXG vector signal generator (VSG) covers up to 54 GHz with 2.5 GHz modulation bandwidth—5 GHz bandwidth with channel bonding—in a single instrument. Adding the V3080A frequency extender, frequency coverage reaches 110 GHz, and using the Keysight PathWave Signal Generation software enables testing to the latest standards and test requirements for wireless and EMSO applications.
Features and Flexibility
The M9484C VXG covers all the 5G NR frequency bands, as well as V- and W-Band for satellite communication links. It generates the complex wideband signals used for carrier aggregation and digital predistortion and delivers excellent RF performance: low phase noise, error vector magnitude (EVM) and adjacent channel power ratio (ACPR). With up to four synchronized and phase-coherent channels in one instrument and more than 32 phase-coherent channels available by daisy-chaining multiple instruments, the VXG greatly simplifies MIMO and beamforming testing. With the capability to simultaneously generate up to eight virtual signals per RF channel, it streamlines complex receiver test scenarios.
Figure 1 VXG EVM vs. output power for a 100 MHz bandwidth 5G NR signal at 39 GHz.
Because many of the new standards and applications require multi-channel functionality, higher frequencies and wider bandwidth, the VXG was designed to provide multi-channel setups with one, two or four channels in a single instrument and more than 32 channels using multiple instruments. The VSG has the capability to create any standards-based waveform with up to 2.5 GHz modulation bandwidth per channel. A four-channel instrument supports intra-band and inter-band aggregation up to 10 GHz.
With some applications using frequency bands above 54 GHz, the compatible 110 GHz frequency extender (V3080A) moves the connection close to the device under test (DUT), reducing path loss and providing high output power to improve the dynamic-range for accurate ACPR and EVM measurements.
Custom ICs
The M9484C was designed to have excellent single-sideband phase noise, signal purity and high power. It delivers the lowest EVM and highest output power in the industry (see Figure 1), achieved with custom MMICs that are used throughout the signal path to ensure measurements reflect the DUT rather than artifacts generated by the instrument. Keysight’s custom MMICs use GaAs and InP processes, which deliver higher output power at the frequencies covered by the VSG (see Figure 2). These custom MMICs combined with the novel signal path architecture provide both high output power and low noise, enabling engineers to both test devices driven into compression and measure device sensitivity close to the noise floor.
Figure 2 Semiconductor process capability: output power vs. frequency.
The Si used in the instrument is equally impressive, including 14-bit digital-to-analog converters running at an 8.5 GHz clock rate and 3 GSPS DSPs with eight real-time processing paths.
GENERATING COMPLEX SIGNALS
Complementing the VXG, Keysight PathWave Signal Generation software simplifies testing to the latest standards and test requirements defined for wireless and EMSO applications. Predefined applications for compliance test setups and auto-configuring signal analysis simplify test workflows. For example, to test the conformance of a 5G NR receiver to the 3GPP 5G NR base station requirements, the software includes 3GPP MIMO fading models and supports the real-time hybrid automatic repeat request. For satellite, automotive radar, new wireless system and aerospace and defense applications, the software can generate custom OFDM and I/Q waveforms.
Keysight’s new graphical interface makes the VXG easy to use, with quick characterization and troubleshooting. PathWave provides “smart” linkages to Keysight’s X-Series signal analyzers, reducing the time spent setting up measurements.
The M9484C VXG is available in seven frequency ranges, from 9 kHz to 6 GHz, to 9 kHz to 54 GHz. The V3080A frequency extender option extends the upper frequency to 110 GHz. The optional PathWave Signal Generation software provides a suite of signal creation tools for the VXG that reduces the time developing test signals for characterizing and verifying compliance with industry standards. The software’s reference signals are validated by Keysight.
Keysight Technologies
Santa Rosa, Calif.
www.keysight.com