Achieving Metrology-grade Results in Vector Network Analysis at Millimeter-wave Frequencies

May 22, 2017

  1. Introduction
  2. Getting Better Results in Millimeter-wave Vector Network Analysis
  3. Enhancing Stability and Precision with Mechanical Innovations
  4. Testing Multiple Components in One Setup
  5. Leveraging a Common Platform for Keysight VNAs
  6. Building on Our Legacy of Innovation
  7. Summary
  8. Keysight in Vector Network Analysis
  9. Related Information

It's easy to underestimate the challenges that arise when working at millimeter-wave frequencies. That's why Keysight is focused on delivering easier access to accurate, repeatable measurements at ever-higher frequencies and wider bandwidths.

The ability to develop off-the-shelf tools for extremely high frequencies follows from our proven blend of measurement science and millimeter-wave expertise. We deliver that expertise inside our hardware and software products, where we put those capabilities at the user's fingertips, and through specialized application engineers who are ready to work side-by-side with our customers.

To help engineers deliver truly competitive next-generation devices and designs, we're focused on creating innovative tools for design, simulation, test and analysis at gigahertz and terahertz frequencies. Our latest innovations are embodied in the Keysight N5290A and N5291A broadband millimeter-wave network analyzers. With these new solutions, developers can reach for unrivalled excellence in their measurements and designs up to 120 GHz (Figure 1).


Figure 1: The N5291A four-port broadband millimeter-wave network analyzer enables developers to confidently characterize their leading-edge designs

Figure 1: The N5291A four-port broadband millimeter-wave network analyzer enables developers to confidently characterize their leading-edge designs.

Getting Better Results in Millimeter-wave Vector Network Analysis

Keysight's new broadband millimeter-wave solution enhances device characterization and modeling by delivering exceptional stability and accuracy for on-wafer and connectorized measurements. Leveraging our world-renowned expertise in metrology and calibration, the new broadband-millimeter wave solution delivers traceable, metrology-grade results at millimeter-wave frequencies. Frequency range is 900 Hz to 120 GHz and the key specifications are magnitude stability of less than 0.015 dB and phase stability of less than 0.15 degrees over a 24-hour period.

The measurement platform is a PNA or PNA-X network analyzer operating at either 26.5 or 67 GHz. The other core elements are a two- or four-port millimeter-wave test-set controller (N5292A, Options 200 and 400, respectively) and a set of compact frequency extenders ("smart modules"). The smart modules include ruggedized 1.0 mm connectors, convection cooling, and built-in characterization data that enables fully calibrated port power at turn-on.

To ensure accurate and repeatable on-wafer results, the N5290/91A solution is compatible with the wafer-level measurement solution (WMS) created by Keysight and solution-partner Cascade Microtech (Figure 2). The WMS includes Cascade Microtech wafer-level probe stations, bias probes, and calibration tools combined with Keysight's test instrumentation and measurement and analysis software. With these attributes, the WMS-based solution delivers the accurate and repeatable wafer-level measurements needed for applications such as device modeling, technology development, process development and specification, process monitoring, component specification, and pilot manufacturing.

Figure 2: This configuration with a four-port N5291A is being used to perform on-wafer measurements of a differential amplifier

Figure 2: This configuration with a four-port N5291A is being used to perform on-wafer measurements of a differential amplifier.

Leveraging our skills in metrology and calibration, the new solution provides measurements that are traceable to national measurement institutes (NMIs). This starts with a 1.0 mm calibration kit (120 GHz), and the ultimate result is traceable measurement uncertainty for key performance parameters such as residual calibration errors and system performance parameters such as dynamic accuracy.

To further enhance measurement results, the user can choose to apply automatic fixture de-embedding to connectorized measurements or perform calibration at the probe tips to ensure greater accuracy in on-wafer measurements.

To help users save time and easily configure complex tasks, Keysight offers several measurement applications that enable deeper insights into device performance:

  • Gain-compression application: Provides complete characterization of amplifiers and frequency converters.
  • Scalar mixer/converter measurements: Support scalar characterization of mixers and frequency converters.
  • Noise-figure measurements: Enable further characterization of frequency converters.
  • Differential and I/Q devices application: Simplifies testing of amplifiers and mixers.
  • Spectrum analyzer application: Provides calibrated multi-channel spectrum analysis up to 120 GHz and beyond.

These measurement applications are also touch-enabled, further simplifying complex operations and providing a more intuitive approach to investigating, characterizing, and troubleshooting broadband millimeter-wave devices.

Another key point: Keysight's customer-centric approach to transportable software licensing makes it possible to buy one copy of a measurement application and share it between multiple instruments. This enhances utilization by letting team members assign needed functionality to a specific instrument, when and where it's needed. It is also more cost-effective than buying a copy of the application for every instrument.

Enhancing Stability and Precision with Mechanical Innovations

At millimeter-wave frequencies, the overall performance of a measurement system also depends on its physical and mechanical design. Inside the new smart modules, Keysight is applying its best-in-class machining capabilities to fabricate wideband coupler technology that provides exceptional stability during measurement calibration.

In the test-set controllers and smart frequency-extender modules, ruggedized 1.0 mm test ports ensure repeatable connections measurement to measurement, day after day. This reduces calibration uncertainty and thereby improves system-level measurement precision.

Testing Multiple Components in One Setup

New-generation monolithic microwave integrated circuits (MMICs) incorporate components that operate in different frequency ranges: baseband, RF, microwave and millimeter-wave. A vector network analyzer (VNA) with single-sweep coverage from hertz to gigahertz enables users to test all those components in one test setup.

Wider frequency coverage also reduces the cost of the test solution. For example, a 900 Hz start frequency in a millimeter-wave network analyzer eliminates the need to purchase a dedicated low-frequency VNA. Using one analyzer also saves time and reduces complexity by streamlining development of test system software.

Greater integration inside MMICs and other wideband designs often means testing more functions per device through fewer access points. The need to connect, disconnect and reconnect the DUT to a VNA or spectrum analyzer is inconvenient and time-consuming whether done manually or automatically through a switch matrix.

The most convenient solution is a VNA with a single-connection/multiple-measurement (SCMM) architecture. As implemented in the Keysight PNA-X network analyzers, users can measure passive or active devices with one set of connections: S-parameters, noise figure, gain compression, THD, IMD, and more. For even greater measurement versatility, the SCMM capability supports the PNA family's spectrum analysis measurement application.

Leveraging a Common Platform for Keysight VNAs

Good usability is beneficial when performing basic measurements such as S-parameters, and it becomes essential when delving into complex tasks such as the characterization of mixers and other frequency-conversion devices. To help ensure excellent results in less time, many customers have asked us to build measurement guides into our instruments and to present those tools on the screen of the analyzer. This is an important and crucial idea, given the time pressures and design requirements most engineers face. It's also a logical and feasible idea that leverages the processor, memory and display in the latest PNA and PNA-X models.

To address these needs, Keysight design engineers pursued parallel advances in measurement performance and front-panel usability. To provide a foundation for next-generation Keysight VNAs, the design team created a common platform that leverages the best attributes of the ENA and PNA families.

Two guiding principles were paramount: be inviting and intuitive for new users; and remain familiar and comfortable for existing ENA or PNA users. The result is a graphical user interface (GUI) that is helpful to engineers who, from time to time, need to make a variety of measurements—simple or complex—while characterizing or troubleshooting a variety of RF components or subsystems. It is also useful to experienced users who occasionally need to make highly complex measurements and will benefit from reminders about the crucial steps and settings (Figure 3).

Figure 3: The new interface includes task-specific guides such as this “millimeter configuration” screen that help new or infrequent users achieve better results

Figure 3: The new interface includes task-specific guides such as this "millimeter configuration" screen that help new or infrequent users achieve better results.

All users will appreciate the familiarity of touch-enabled GUI technology similar to that used in smartphones, tablets and laptops. The updated PNA Series network analyzers include the following attributes:

  • 12.1-inch widescreen display with multi-touch GUI
  • Easy access to frequently used functions
  • Quick setups using touch-activated tabbed softkeys and dialog menus
  • Intuitive single- and multi-touch gestures to drag-and-drop or magnify traces
  • Versatile, touch-driven marker capabilities

For added flexibility, the user can also customize the placement of traces and windows on the analyzer screen. Example capabilities include optimal arrangement of traces from multiple measurement channels and multi-page measurement displays through a "tabbed sheet" function.

Building on Our Legacy of Innovation

Although millimeter-wave has recently started to ramp up in commercial applications, Keysight has been advancing the learning curve for decades. Under the Hewlett-Packard brand, our earliest gigahertz products date back to 1967 and the introduction of the HP 8410 network analyzer, which could measure up to 12 GHz and also compute S-parameters. Our first millimeter-wave equipment followed in the late 1980s with signal generators that reached above 26.5 GHz with upconverters, and broadband network analyzers that covered 45 MHz to 100 GHz.

Currently, many of our signal generators, spectrum analyzers and network analyzers can cover frequencies between 50 GHz and 1.5 THz using frequency-extender products from two of our solution partners, Virginia Diode, Inc. (VDI) and OML, Inc. Working with VDI, we recently deployed a VNA-based solution that includes spectrum analysis capability up to 1.5 THz.

More recently, with the broadband millimeter-wave network analyzer, the 1.0 mm calibration kit (120 GHz) represents yet another significant contribution. For key performance parameters, calibration ensures measurement uncertainty that is traceable to an NMI.


With the N5290/91A broadband millimeter-wave solutions, engineers can continue to count on Keysight to give them easier access to accurate, repeatable measurements at ever-higher frequencies and wider bandwidths. Built on a foundation of electronic and mechanical breakthroughs, the N5290/91A delivers metrology-grade precision that ensures unparalleled system-level performance. As a result, developers will be able to confidently characterize and optimize their devices at frequencies up to 120 GHz.

Keysight in Vector Network Analysis

Whether testing is focused on active or passive devices, the right mix of speed and performance gives end-users an edge. In R&D, Keysight VNAs provide a level of measurement integrity that helps developers transform deeper understanding into better designs. On the production line, our cost-effective VNAs provide the throughput and repeatability needed to transform undifferentiated parts into competitive components. In the field, our handheld analyzers deliver high-quality measurements wherever users need to go.

Every Keysight VNA is the ultimate expression of our expertise in linear and nonlinear device characterization. On the bench, in a rack or in the field, we help our customers gain deeper confidence.

About Keysight Technologies

Keysight Technologies is a leading technology company that helps its engineering, enterprise and service provider customers optimize networks and bring electronic products to market faster and at a lower cost.  Keysight's solutions go where the electronic signal goes, from design simulation, to prototype validation, to manufacturing test, to optimization in networks and cloud environments.  Customers span the worldwide communications ecosystem, aerospace and defense, automotive, energy, semiconductor and general electronics end markets.  Keysight generated revenues of $2.9B in fiscal year 2016. In April 2017, Keysight acquired Ixia, a leader in network test, visibility, and security. More information is available at

Related Information

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