Microwave Journal

Rohde & Schwarz Demonstrates New Microwave Instruments

May 25, 2010

Rohde & Schwarz is demonstrating a broad array of high-performance instruments and unique measurement capabilities at IMS 2010, including the industry’s first 67 GHz vector network analyzer (VNA) with four integrated ports, four internal and independent sources, and eight receivers; large-signal network analysis; fast electronic source and load-pull measurement capabilities; and much more.

The new R&S®ZVA67 is the industry’s first 67 GHz VNA with four integrated ports, four internal and independent sources, and eight receivers, which greatly simplifies the test setup and enables advanced measurement capabilities. The instrument has the broadest dynamic range, highest RF output power, and fastest measurement speed of any instrument in its class.

The R&S ZVA67 sets several benchmarks for millimeter-wave VNAs. It is the first 67 GHz VNA with four internal sources for fast two-tone measurements of amplifiers and mixers, the first to generate phase-coherent signals, as well as the first with IF bandwidths up to 30 MHz for pulsed measurement of amplifier performance. The instrument incorporates all of the features of the company’s ZVA Series VNA family and applies them to millimeter-wave measurements with high speed and accuracy.

It has short measurement times thanks to its fast internal synthesizers, high dynamic range, more than 100 traces and channels, a measurement wizard for easy setup of multiport and balanced measurements, simple error-free calibration, multiple calibration techniques for test fixtures as well as coaxial and on-wafer applications, optional automatic calibration, virtual and true differential mode for linear and nonlinear tests of differential components, simultaneous measurement of noise figure and S-parameters, and a wide sweep range for small- and large-signal analysis in a single sweep.

The test set of the R&S ZVA provides one measurement channel and one reference channel for each test port, an RF switch in each generator path, and one generator for each pair of test ports. Measurement time per test point is less than 3.5 µs in the CW mode and a frequency sweep over 200 test points takes less than 5 ms without compromising measurement accuracy. In addition, when two or more devices are being tested, there is no need to load the required instrument setups from the hard disk one after the other. Once called, setups remain available in RAM including calculated data, so it is possible to switch between setups with virtually no delay.

Rohde & Schwarz will demonstrate the ZVxPlus nonlinear vector network analyzer application developed by NMDG for large-signal network analysis using NMDG’s S-functions for characterizing nonlinear components under large-signal conditions. ZVxPlus in combination with Rohde & Schwarz VNAs and AWR’s Microwave Office® high-frequency design software allows direct measurement and simulation of RF and microwave systems under measurement conditions representative of what nonlinear devices will experience in operation.

As a natural extension of S-parameters for nonlinear components, S-functions simplify and accelerate the design process of nonlinear components by providing more complete system-level models, enabling the prediction of harmonic and modulation behavior under different mismatch conditions. As with S-parameters, S-functions can be cascaded to predict nonlinear behavior of circuits and systems.

The S-function extraction tool enables creation of a measurement-based behavioral model for active components, and the ability to verify it, and export it to design tools. The application can collect measurement data for a sweep list of Large-Signal Operating Points (LSOP) such as sweep of DC bias points and large signal input powers. The S-functions can be extracted for a given set of harmonics taking into account corresponding harmonic output impedances. The component does not have to be matched.

With minimal effort and time, a behavioral model for transistor, amplifier, prescaler, mixer, or other device can be created and verified using the Rohde & Schwarz VNA. When imported into Microwave Office software, the S-functions make it possible to directly design large-signal circuits using the measured data or to provide more detailed data sheets. Using data collected directly in the simulation tool, S-function models can be extracted and used to compress or hide specifics of nonlinear circuits in the main design software.

Rohde & Schwarz and NMDG will showcase NMDG’s NM600 all-electronic Fast Source and Load-Pull (FSLP) application. Using a single Rohde & Schwarz VNA with two internal RF sources, FSLP characterizes active components under various input and output mismatch conditions without the need for a traditional source and load-pull setup. FSLP captures the fundamental behavior of active components or circuits based on incident and scattered voltage waves at both ports under any set of input and output load conditions.

The behavior of the component is first saved for a selection of bias points, fundamental frequencies, input powers and output load impedances. Different derived quantities, such as power gain, input and output powers, or power added efficiency (PAE), can then be visualized versus input and output mismatch conditions. This allows designers to easily obtain the best source and load matching network parameters to interface two different stages using a minimal number of iterations.

FSLP also performs the necessary measurements to derive a fundamental S-function model when complemented by Microwave Office software. This model makes it possible to predict the behavior of active components or circuits at the fundamental frequency under varying source and load conditions or in interaction with other components.

Rohde & Schwarz has developed and patented a method for measuring the group delay of mixers and multiple-stage converters when access to a device’s LO is unavailable. Because it does not require access to the LO of the device under test it is well suited for applications such as satellite communication links and other highly-integrated devices in which the LO is embedded within the circuit and is not accessible for test purposes. It offers the additional benefits of being independent of LO drift and phase noise and requires no external reference mixers. The solution is extremely fast, accurate and easy to use, and is available as an option for all four-port R&S®ZVA and R&S®ZVT Series of vector network analyzers.

Group delay is the time a signal takes to pass from the input to the output of a device and can cause signal distortion if not constant within the frequency band. This makes the measurement of group delay and deviation from linear phase essential to evaluate the performance of wireless communication systems employing higher-order modulation schemes. Stability and accuracy of conventional group delay measurement methods that require access to the LO or try to reconstruct the LO with an external source are susceptible to variations of frequency and phase of the device’s LO if it is not accessible. The benefits of the Rohde & Schwarz technique are equally important for evaluating devices with multiple mixing stages.

Rohde & Schwarz will showcase an extremely accurate approach for making high-power pulsed-signal measurements from the device to system level. It is extremely useful for evaluating components employed in radar systems, wireless power amplifiers and other high-power applications. When equipped with the R&S®ZVAX24 extension unit, measurement of active devices is simplified by creating virtually any arbitrary pulsed waveform and performing a wide array of measurements with only a single connection to the device under test.

The R&S®ZVAX24, which is an option for all R&S®ZVA Series four-port VNAs, incorporates pulse modulators, harmonic filters, an internal combiner and high-power couplers to make measurements on active devices with power levels up to +43 dBm. The pulse modulators are controlled by the pulse generators in the VNA, providing the R&S®ZVA Series instruments with both pulse generation and pulse modulation capability. As the pulse generators are resident in the VNA, any pulse train waveform can be created, including pulse trains, single pulses and virtually any arbitrary pulsed waveform.

As a result, high-power S parameter and pulse measurements can be performed with a single connection to the device under test because the R&S®ZVAX24 contains internal harmonic filters as well. The R&S®ZVAX24 has a pulse modulator in the receive path of the VNA’s second port that allows analog gating, which is more accurate and repeatable than when implemented digitally via software. Gating capability makes the measurement system especially well suited for radar cross-section (RCS) measurements that require a gated response in order to avoid multipath distortion.

The pulsed-signal measurements achievable with the system include average, point-in-pulse, pulse profiling with 12.5-ns time resolution, and the chopped RF method. Harmonic rejection is greater than 60 dBc at maximum power, and the internal high-power coupler when combined with a free intermodulation wizard available from Rohde & Schwarz makes third-order intercept and intermodulation distortion measurements fast and easy to set up.

Rohde & Schwarz and X-COM Systems will demonstrate an RF capture, playback and analysis solution for complex RF signal environments. The system employs the RF and baseband interfaces on the R&S®FSV spectrum analyzer and R&S®SMBV signal generator families coupled with IQ capture, storage and software from X-COM Systems. The capture system provides high-resolution 16b I and Q storage of signals up to 40 MHz bandwidth for up to one hour with internal memory or up to five hours using external datapacks.

The X-COM Systems software provides the ability to record continuous streams of very wide bandwidth data with no gaps and can time-stamp recorded data, accepts a trigger to mark events in the data, and provides expandable drives for virtually endless no-gap signal storage. Recorded data streams are available in near real-time and can be played back digitally directly into the R&S®FSV with playback time equaling the record time. Alternatively, the digital playback can be input to the R&S®SMU200A vector signal generator and up-converted to the RF spectrum. Playback can be nearly instantaneous.

The user can play or repeat any portion of the signal and has complete control of what data to play including marked data. Data sets can be combined and new signals can be introduced for scenario testing, and marked data is easy to find in large data files. Defined data ranges can also be exported to maintain smaller file sizes. The system uses an unencrypted, open data format and security can be maintained with all data on removable hard drives.