mmW and Sub-THz 50Ω Gain Compression and Load Pull Measurements


Maury Microwave has over ten years of experience designing, implementing and supporting millimeter-wave (mmW) device characterization systems between 50 and 110 GHz. These systems are built around Maury's patented automated waveguide tuners for non-50ohm measurements, and Maury's measurement and modeling device characterization software suites. In addition, Maury integrates commercial Vector Network Analyzers (VNA), signal generators, spectrum analyzers, noise figure analyzers, mmW frequency extenders and related components and accessories to complete systematic and semi-automated device measurements at the DUT reference plane.

Fully integrated mmW device characterization systems may include the following measurement capabilities: small-signal S-parameters, source pull for noise parameter extraction (Fmin, Gamma_opt, rn), and large signal load pull for power, gain, efficiency and intermodulation distortion (IMD with optional second input source and analyzer).

It is critical to consider probe station integration for on-wafer measurements at the time of system conception, as the various components (mmW extenders, downconverters, switches, automated attenuators, tuners...) will need to be mounted on the prober platen, as well as balanced for vibration-free operation. Maury integrations are compatible with most Cascade (including Suss), MPI, Signatone, Semiprobe and third party probe stations.

mmW device characterization systems are available in WR15 (50-75 GHz), WR12 (60-90 GHz) and WR10 (75-110 GHz) configurations.

Millimeter-wave (mmW) Device Characterization Systems

The Need For Large Signal Measurements at mmW and Sub-THz Frequencies

Performing device characterization measurements at millimeter-wave and sub-THz frequencies can be challenging for several reasons. First, it’s difficult to achieve accurate and repeatable power-control at the DUT reference plane when using waveguide extenders between 110 GHz and 1.1 THz, as the extenders typically output a fixed power. However, controlling the power delivered to the input of the DUT is critical in setting the device’s operating conditions and characterizing its performance over power, such as the large-signal characteristic gain compression. Second, load pull, which means changing the load impedance presented to the DUT to an arbitrary non-50Ω value, is difficult as passive load pull impedance tuners are typically unavailable above 110 GHz, and even then, are limited in their ability to present high mismatches at the DUT reference plane.

Load pull measurements are necessary for transistor designers to properly characterize and model the high-speed behaviors of their devices. For circuit designers, load pull measurements are used to determine the ideal matching conditions and optimize performance, at powers where every fraction of a dB is important. Load pull can also be used to test systems, such as new mm-wave radars, where both contacted and over-the-air performance testing is needed.

Enabling mmW and Sub-THz 50Ω Gain Compression and Load Pull Measurements

MMW-STUDIO mmW and Sub-THz characterization software, offered by Maury Microwave and Vertigo Technologies, is a software suite designed to work with a 4-port VNA using waveguide extender modules and add accurate and repeatable high-resolution power control. The software enables the direct measurement of vector corrected power at the DUT reference plane, as well as control over the power delivered to the DUT. Doing so allows engineers to perform gain compression power sweep measurements over the available level of powers, and to perform S-parameter measurements at any arbitrary power level.

MMW-STUDIO LP is a software add-on, which when used in conjunction with a Vector Modulation Unit (VMU), enables control over the magnitude and phase of the signals delivered to the input and output of the DUT. This enables an engineer to set arbitrary impedances, or perform active load pull measurements, where the magnitude of reflection presented to the DUT is achieved by controlling the reflected a2 wave and fulfilling Γ=a2/b2.

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Application Notes and Data Sheets

ARFTG 2015 Technical Paper

Power Control for S-parameters and Large Signal Characterization at(sub)-mmWave frequencies Power Control for S-parameters and Large Signal Characterization at (sub)-mmWave frequencies

ARFTG 2016 Technical Paper

Power Level Control of mm-Wave Test Benches for Accurate Small and Large-signal DUT Measurements Power Level Control of mm-Wave Test Benches for Accurate Small and Large-signal DUT Measurements

Maury Application Notes Library

Maury Software and System Application Notes. Maury Application Notes Library