A Broadband Vector Network Analyzer

ON THE COVER

A Broadband Vector Network Analyzer

Microwave Measurements Division, Anritsu Company
Morgan Hill, CA

A new high performance, broadband measurement solution is being introduced. The model ME7808A broadband vector network analyzer (VNA) covers the 40 MHz to 110 GHz frequency range in a single high speed sweep. The instrument is built on the advanced technology of the Lightning 65 GHz VNA and is ideal for making accurate S-parameter measurements of high frequency components and devices. The new broadband VNA's flexible architecture makes it easily adaptable to multiple measurement applications.

SYSTEM CONFIGURATION

The ME7808A VNA is comprised of the Lightning 65 GHz VNA and millimeter-wave (mmW) modules that extend the coverage to the 65 to 110 GHz W-band, as well as multiplexing couplers (shown in Figure 1), two synthesized frequency sources and a broadband test set. Option 12 of the Lightning VNA adds rear panel IF inputs that interface with the millimeter modules and forms the foundation for the new broadband instrument. The Lightning VNA also controls two synthesizers that provide the RF and LO drive to the mmW modules. In addition to S-parameter measurements, the new VNA supports time-domain and swept power gain compression measurements as well. Internal test port attenuators, bias tees and a wide automatic level control range provide flexibility for active device characterization. Multiple storage formats and ample hard disk space make it convenient to save test results and measurement setups.
 

The broadband test set drives the two external mmW modules that boost the instruments frequency coverage to 110 GHz. The test set performs band switching between the 40 MHz to 65 GHz VNA and the 65 to 110 GHz mmW module so as to create the broadband sweep. In addition, the test set routes the IF outputs from the mmW modules back to the VNA. A 20 dB variable attenuator is built into each mmW module to provide output power control.

The broadband VNA utilizes two 20 GHz synthesized frequency sources to provide the LO and RF drive signals to the mmW modules. These synthesizers are the latest technology and may be upgraded at any time to add features such as expanded modulation capability or improved phase noise performance for other applications.

The ME7808A combines the 40 MHz to 65 GHz output from the Lightning VNA and the 65 to 110 GHz output from the mmW modules using a unique multiplexing coupler design. The effective system test ports for broadband operation are two W1 (1mm) coaxial connectors. The W1 connector is compatible with the IEEE standard 1 mm connector. This configuration provides a DC path that permits bias injection from the VNA front panel bias inputs directly to the W1 coax test ports.

THREE SYSTEMS IN ONE

Using the approach of coupling the 65 GHz VNA with the mmW modules essentially offers three systems in one. As described, the broadband configuration provides 40 MHz to 110 GHz with a W1 connector output. The 65 GHz VNA can also be used as a stand-alone instrument with a V-connector interface. Finally, the ME7808A can be used as a millimeter-wave VNA with a WR-10 waveguide interface. In addition, discrete mmW bands are easily supported by substituting other available mmW modules into the system. When operating either the 65 GHz or mmW systems independently, higher output power and increased dynamic range are achievable. Table 1 lists the ME7808A system's typical dynamic range performance.

ON-WAFER MEASUREMENTS

Wafer probe tips can be connected to any of the three interfaces to make on-wafer measurements. The mmW modules are small and lightweight enough to be mounted on the micropositioners associated with semi-automatic or manual probe stations. Figure 2 shows a complete on-wafer measurement solution comprised of the ME7808A VNA integrated with a Karl Suss PA200 probe system. Figure 3 illustrates a time-domain measurement of a 6600 µm open-ended transmission line showing composite directivity and port match on-wafer. Figure 4 displays an on-wafer broadband measurement of a 0.1 µm InP HEMT.
 

Device characterization and parameter extraction is most commonly performed on a wafer probe system, requiring specific on-wafer calibration methods. The new VNA provides an easy interface for entering the parameters of the common calibration methods. Other calibration techniques optimized for wafer probing applications are also supported for users of Karl Suss and Cascade Microtech probe systems.

The new VNA is fully compatible with Karl Suss wafer probe stations and GGB Industries Picoprobe^® tips. Cascade Microtech's probe stations and WinCal calibration software are also compatible. For parameter extraction and device modeling, an EEsof IC-CAP driver is available for the ME7808A system.

CONCLUSION

A new broadband high speed VNA is available to cover the 40 MHz to 110 GHz frequency range in a single sweep. The measurement system provides both flexibility in configuration and the ability to upgrade for future requirements. In addition, an available option replaces the 65 GHz VNA with a 50 GHz version and deletes the multiplexing coupler and 65 to 110 GHz modules. Modules covering 50 to 75, 60 to 90, 56 to 94, 75 to 110 or 90 to 140 GHz may be selected separately as desired. Additional information may be obtained from the company's Web site at www.us.anritsu.com. 

Microwave Measurements Division, Anritsu Company,
Morgan Hill, CA (800) 267-4878.

Circle No. 302