The High Speed Measurement Group’s work applies to a wide variety of communications and computing technologies, and is of particular importance to CTL’s Next-Generation 5G Wireless and Fundamental Metrology for Communications program areas. To facilitate these programs we develop standards and metrology for the ultrafast circuits needed for the communications and computer networks of the future. Our group includes two primary projects: Linear and Nonlinear Network Analysis and Waveform Metrology.
LINEAR AND NONLINEAR NETWORK ANALYSIS
The Linear and Nonlinear Network Analysis Project leverages expertise in network analysis to improve measurements for communications both within and outside of CTL, and develops state-of-the-art tools for communications-systems design, particularly the highly integrated systems-on-a-chip designs that now drive the communications industry.
Nonlinear Network Analysis
Large-signal network analysis (LSNA) techniques can be used to measure the non-linear response of RF systems by acquiring both the phase and amplitude of the fundamental and its harmonics. These tools bring a rigorous and coordinated measurement and modelling approach to the characterization of complex signals and communication systems, as well as supporting the characterization of materials, devices, components and subsystems important to the communications ecosystem. At NIST, we are using LSNA techniques for accurate characterization of over-the-air-test configurations, channel-sounders and channel-models, linear and nonlinear interactions in multi-element antennas, and waveform and modulated-signal characterization.
DC-THz On-Wafer Measurements
This project is dedicated to improving on-chip measurement of very-high-speed transistors (into the hundreds of gigahertz) as well as characterizing the nonlinear behavior of high-power, lower-frequency (microwave to millimeter-wave) transistors. Combinations of these transistors will be indispensable to next-generation wireless systems and open up new high-frequency spectrum to the wireless industry. There are two exciting activities within this program sponsored by the NIST Innovations in Measurement Science awards: Josephson Arbitrary Waveform Synthesizer (JAWS) and the DC to 1 THz Large-Amplitude Optoelectronic Multitone Electrical-Signal Synthesizer.
Microwave Uncertainty Analysis
The NIST Microwave Uncertainty Framework is a software tool developed to calculate uncertainty using conventional error-propagation analysis and Monte-Carlo analysis. Active development of this framework includes propagation of correlated uncertainties (which are required for traceable modulated signal measurements and many communication metrics), extending uncertainty propagation to nonlinear processes and system-level applications, and facilitating complex correlated uncertainty analyses required by the traceability chains of modern communications systems. Furthermore, we are using this framework to establish traceability for mmWave channel measurements, critical to development of 5G technologies.
WAVEFORM METROLOGY PROJECT
The Waveform Metrology Project focuses on improving the characterization of high-speed waveforms to establish and solidify the foundations of future high-speed wireless communications. Through various measurement services, we develop optoelectronic and statistical signal analysis techniques to provide traceability for high-speed test instrumentation and, by extension, high-speed wireless systems. In this work, we apply techniques NIST pioneered and has applied not only to wireless hardware, but also to fiber optics and integrated circuits.
Primary Waveform Traceability
This project has historically developed optoelectronic and statistical signal analysis techniques to characterize high-speed instrumentation used by the fiber optics, digital IC, and wireless industries as well as the Department of Defense (DoD) Primary Standards Laboratories and DoD contractors. Four NIST innovations lie at the core of the project’s work: calibration of impedance mismatch and loss effects in signal measurements; traceable electro-optic sampling (EOS) for frequency-response calibration; the calibration of timing errors, response errors and impedance effects in sampling oscilloscopes; and uncertainty analysis that transforms waveform uncertainties between the time and frequency domains.
NIST was the first NMI to develop phase calibration capability through EOS and to map this calibration into waveform measurements and waveform measurement uncertainty. The Waveform Metrology Project maintains several calibration services that are used to provide traceability for commercial instrumentation, such as large signal network analyzers, lightwave component analyzers, vector signal analyzers, oscilloscopes, pulsed laser radiometers, and optical time-domain radiometers. NMIs in South Korea, China, Germany, and the U.K. are actively working on developing similar waveform measurement services.