Vector Network Analyzers For Measurement to 50 GHz

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Vector Network Analyzers For Measurements to 50 GHz

Agilent Technologies Inc.
Santa Rosa, CA

The HP 8510 vector network analyzer introduced by Hewlett-Packard in 1985 revolutionized microwave measurements by combining advanced techniques for characterizing components with the computational power afforded by the microprocessor. For the first time, designers could perform functions such as generating the time-domain characteristic of a signal passing through a MMIC. As a result, the 8510 quickly became the industry standard and further extended its capabilities over the succeeding years. Now Agilent Technologies has introduced a new suite of vector network analyzers into its PNA Series that promises to establish a new meaning for the term high performance in microwave measurements.

The new instruments include:

• The E8364A, a two-port, four-receiver analyzer aimed at applications to 50 GHz. It is based on the company's recently introduced PNA platform, which has the highest measurement speed and greatest measurement accuracy of any VNA in the company's history.
• The E8800A Series of two-port, three-receiver network analyzers with measurement coverage to 3, 6 or 9 GHz.
• The N3380A Series of three-port, four-receiver network analyzers, also with measurement coverage to 3, 6 or 9 GHz.

Each of the three instrument suites was created to serve the measurement needs of specific types of customers. Appendix A lists key performance characteristics of the three instrument series.

The E8364A is the successor to the 85107 (the 50 GHz version of the 8510) and the company's flagship VNA. It capitalizes on the PNA Series strengths of extremely fast measurement speed, easy-to-use interface, advanced connectivity, high dynamic range, advanced programming capability and built-in help system. It has two measurement ports and uses four mixer-based receivers, which results in a lower instrument noise floor and enables in-fixture and on-wafer measurements. Even at its high frequency measurement limit of 50 GHz, the standard E8364A boasts its sweep speed is as fast as 35 microseconds per point, dynamic range greater than 103 dB and trace noise of < 0.06 dB RMS. With a configurable test set that includes a preamplifier, reversed coupler and segment sweep, the performance is dramatically higher (see Appendix B ).

Together these performance characteristics allow the E8364A to perform extremely accurate measurements of microwave devices such as amplifiers, filters, attenuators, cables and phase shifters, as well as the optical components such as high speed photodetectors and optical modulators employed in fiber-based communications networks. While the measurement speed of the E8364A makes it well suited for the production test environment, its high level of accuracy serves R&D and production engineering as well.

The 3, 6 and 9 GHz E8800A and N3380A series are well-suited for manufacturers of 2.5G and 3G wireless basestation components, including filter/LNA combinations, duplexers and power combiner/dividers. They are also an excellent choice for small-signal gain characterization of amplifiers.

The three-port N3380A Series has a four-receiver architecture that improves measurement throughput when measuring three-port devices. This architecture allows all nine S-parameters to be measured in three sweeps. The instrument includes the full three-port calibration needed for design and test of low isolation devices such as couplers and duplexers.

The lower cost, two-port E8800 Series is aimed at component manufacturers who still require PNA-level performance, but who want to optionally configure the analyzer for their needs.

All seven of the new instruments benefit from new calibration techniques, including sliding load, multiple line lengths for TRL calibration and adaptor removal, which together allow users to maintain high accuracy, especially when making measurements at microwave frequencies. In addition, the instruments also benefit from enhancements to marker functions and printing options, as well as new I/O capabilities. The new 3, 6 and 9 GHz models provide as options many features that were initially standard in earlier PNA instruments. This option structure lowers instrument cost, as does the availability of the three-receiver series, for cost-sensitive manufacturers.

PC Merged With VNA

The PNA Series, which was introduced a year ago, is based on an entirely new platform that operates under the Windows 2000 Professional operating system. While "windows-like" user interfaces have been available in many types of instruments for years, the PNA Series fully integrates the PC and microwave measurement architectures, which results in capabilities that each one alone cannot perform.

For example, the PNA Series instruments can be integrated into the corporate enterprise the same as any other node on the network, and can take advantage of facilities such as network-attached storage, peripherals, software, off-line data analysis capabilities and most any other capability resident on the network. Since they can connect to the Internet with a Web browser, stored instrument and measurement data can be communicated anywhere, and firmware can be upgraded in place by a download from the company's Web site. Diagnostics can be performed remotely as well. Data analysis can be performed either locally on the instrument, or virtually anywhere via the Internet.

The PNA Series instruments also allow programming using Standard Commands for Programmable Instruments (SCPI) or Component Object Model (COM) and Distributed Component Object Model (DCOM) commands, which can be executed over a LAN interface or within the instrument (SCPI can also be executed over GPIB). Code can be executed directly from the analyzer or over a LAN or GPIB, and developed in popular programs such as LabVIEW, Visual Basic, Visual C++ or Agilent-VEE. Instrument set-ups and measurement data can be stored on the internal hard drive, diskette, optional CD-RW via Universal Serial Bus (USB) or remote network drive, and instrument control is afforded over a LAN, or via GPIB, parallel or serial interfaces.

Conclusion

The measurement requirements of RF and microwave component and system manufacturers vary greatly. In some cases, measurement speed and performance are paramount; in others connectivity or the need to make measurements at high frequencies are most important. The new PNA Series instruments make it possible to configure measurement capabilities to match specific user requirements, which can significantly reduce acquisition cost. However, since all of the instruments possess the same basic PNA Series architecture, a high level of performance is maintained regardless of the chosen configuration. More information can be found at www.agilent.com/find/pna.

Agilent Technologies Inc.,
Santa Rosa, CA,
www.agilent.com.

Circle No. 302