Use Agilent PNA-X network analyzer to realize millimeter wave measurement

Between 30 and 300 GHz, the application of millimeter wave measurement is increasing. From high data rates to the automotive industry to radio astronomy, flexible measurement solutions are increasingly showing their advantages. In these applications, millimeter wave measurement solutions must comply with many rules. For example, the characterization of wafer devices in the detection environment, or module testing through waveguide or coaxial interfaces. Solutions also include material measurement in fixtures or free space, or outdoor/indoor antenna testing.

Compared with applications below 3 GHz, the current requirements for millimeter wave components are relatively low, but the expected performance is very high. Therefore, a measurement solution with an expandable frequency range and measurement capability will provide greater flexibility to adapt to multiple applications.

In many emerging electronic technologies, the initial components (for example, devices made on wafers) are the basic building blocks. After that, these devices are cut into squares and added to the circuit through wire bonding, and finally become highly integrated modules with increased functions and packaged into a small volume. Before further testing as a module, the device is a characterised wafer. The data obtained when testing these wafer devices can be used for parameter extraction to build a model, and then the model can be used for circuit simulation.

make millimeter wave measurement

The circuit simulation model established by 　　 requires a high-quality, 220-GHz detection solution. For example, Figure 1 shows a 50-nm T-gate deformed GaAs HEMT wafer measurement from 140 to 220 GHz1. All 4 S parameters can be viewed at the same time. Look at the trace S21 at the bottom left, which intersects the X axis at approximately 150 GHz. In order to reveal the true gain of the device, it is necessary to use the .s2p file (raw data) for de-embedding processing, which can be performed inside the network analyzer or offline.

Use Agilent N5250A PNA series millimeter wave network analyzer (with 140 to 220GHz (N5260AW05) test probe module) for measurement, and Cascade Microtech's Summit series 12K probe station for wafer measurement. (Figure 2 shows the 110-GHz version of the system). All dual-port wafer calibrations are performed using Cascade Microtech's WinCal 2006 calibration software, and the execution sequence is through, reflection, reflection, and matching (LRRM).

Using Agilent PNA-X network analyzer to realize millimeter wave measurement

By adding a modulator (Agilent Z5623AH81) and a dual output pulse generator (Agilent 81110A), the same device is transformed into a solution for pulse measurement. Figure 3 shows the pulse profiling measurement of a simple pass-through device in the W band from 75 to 110 GHz. The pulse settings used for these measurements are as follows:

RF pulse width (PW): 2μs (50% duty cycle); pulse width (PW) can be reduced to 20 ns

B receiver strobe pulse width: 20 ns (0.5% duty cycle)

Measuring frequency: 100 GHz

Pulse shape is a very useful analysis tool because it can display any pulse distortion caused by the device under test (DUT). It is done by using a pulse signal at the input end to excite the device under test, and then folding back the signal at the output end to determine the pulse shape change. All these changes imply non-ideal (for example, non-linear) behavior of the device under test (DUT).

Modifying the system to cover different millimeter wave frequency bands is as easy as changing the test probe module. For example, replacing the N5260AW05 (140 to 220 GHz) module with N5260AW03 can transform the frequency band from 220 to 325 GHz. By adding two external frequency integrated signal sources (for example, Agilent PSG signal generator), the dynamic range or trace noise of the system can be easily increased above 200 GHz. Each frequency integrated signal source is configured with 520 options to meet the 20 GHz frequency range; one provides RF signals, and the other provides local oscillator (LO).

The same device settings can also be used to perform related measurements, such as average pulses, points within pulses, and pulse-to-pulse measurements. This configuration can also be used for indoor antenna measurements, using pulsed millimeter wave technology to filter out unwanted signals.

In addition to wafer, pulse and antenna applications, millimeter wave solutions are also widely used for material measurement. Figure 4 shows the W-band 75 to 110 GHz system for material measurement in free space. Due to the small size of the W-band waveguide interface, free space technology can provide a more manageable sampling volume (compared to the W-band waveguide interface volume). With a millimeter wave solution, Agilent’s unique gate-reflect-line (GRL) calibration technology can be used, so that it can provide high voltage without additional hardware (usually more expensive).

  in conclusion

As shown in the previous example, the millimeter wave solution of the PNA series network analyzer can be modified to suit a variety of different applications (Figure 5). This general solution is an effective way to meet today's wide range of applications and disciplines. It also reduces the need for multiple single-target measurement systems.

For future frequency band millimeter wave applications, Agilent PNA-X network analyzer (N5242A) can also solve all the measurements mentioned here. To take full advantage of the capabilities and capabilities of this analyzer, simply replace the PNA (E836xB) with N5242A in each of the solutions shown.