TestBench, November 2009: Driving Next-generation Designs with an Evolutionary Signal Analyzer
The Agilent PXA signal analyzer is ready to evolve with changing requirements
When developing next-generation microwave devices, high performance in a signal analyzer makes it possible to find and fix anomalies in less time. Of course, the problems change from day to day: today it might be a low-level spur hiding near a strong fundamental; tomorrow it could be an intermittent glitch in a complex new modulation scheme.
To help designers handle whatever may crop up next, the Agilent N9030A PXA signal analyzer combines exceptional performance with reconfigurable measurement capabilities and a future-ready architecture. The result is an analyzer that can evolve with changing requirements in current- and next-generation designs (Figure 1).
Figure 1. The Agilent PXA signal analyzer is an evolutionary replacement for existing high-performance spectrum analyzers. It includes seven internal expansion slots, a generous power supply, and easily replaceable/upgradable CPU and disk drive assemblies.
Creating a solid foundation
In the PXA signal analyzer, performance is the bedrock of new insights. Spurious-free dynamic range of up to 75 dB at analysis bandwidths of up to 140 MHz (optional) make it possible to see more signals in less time. Sensitivity of –172 dBm displayed average noise level (DANL) at 2 GHz (preamp on) enables a deeper look at the frequency spectrum.
Of greater importance is the analyzer’s noise floor, which can be a limiting factor in several types of measurements. For example, noise limits the low end of dynamic range and also affects the accuracy of measurements on small signals.
The PXA signal analyzer combines real-time processing with characterization of the analyzer’s own noise, enabling the removal of that noise from measurements. The results of this technique, which Agilent calls Noise Floor Extension (NFE), vary from about 3.5 dB for continuous wave (CW) to 8 dB or more for pulsed and noise-like signals. Typical DANL at 2 GHz is –161 dBm without a preamp and a remarkable –172 dBm with a preamp. An example of the improvement from NFE is shown in Figure 2.
Figure 2: Agilent’s Noise Floor Extension (NFE) technology can dramatically improve analyzer noise floor, revealing some signals and allowing others to be more accurately measured. These before/after traces of the same signal are shown at 3 dB/div.
Staying flexible for evolving requirements
In its base configuration, the PXA signal analyzer offers outstanding performance. Every unit includes “I/Q analyzer” functionality and the Agilent PowerSuite. The I/Q analyzer mode allows viewing of magnitude, phase or I/Q behavior of complex modulated signals over the maximum available analysis bandwidth. PowerSuite provides a variety of one-button, standards-based power and spectrum measurements such as adjacent-channel power, third-order intermodulation (TOI), harmonic distortion and burst power.
The PXA can also be configured and reconfigured to fit evolving requirements. This starts with optional advanced measurement applications such as noise figure and phase noise that integrate into the analyzer interface. Based on proven algorithms, the library of measurement applications ensures consistent results when transitioning from legacy signal analyzers such as the Agilent PSA or the current-generation Agilent X-Series. The applications are also transportable across the Agilent X-Series, which includes the PXA, MXA, EXA and CXA signal analyzers. For greater flexibility, the Agilent 89600 vector signal analysis (VSA) software can run inside the instrument, providing advanced analysis of more than 70 signal formats.
Enabling future enhancements
A truly future-ready signal analyzer offers the flexibility to upgrade and enhance every major subsystem: mechanical, electronic, firmware and software. The PXA addresses all four areas:
• Its mechanical assembly provides seven expansion slots for future enhancements.
• A removable CPU motherboard enables CPU, memory and I/O upgrades.
• The firmware-based X-Series measurement applications add specific or standards-compliant capabilities.
• An open Microsoft Windows operating system runs software applications inside the analyzer.
These capabilities let the PXA evolve as needs change—and help protect an investment in advanced test equipment.
Additional flexibility comes from the standard and optional removable disk drives. For example, the standard PXA includes a SATA HDD that can be replaced with an optional SSD or e-SATA drive. Provisions have been made for an optional PCIe interface that can be used to capture streams of gap-free, fully calibrated I/Q samples for detailed post-processing and analysis.
In the design of microwave devices, the problems change from day to day and from project to project. The high performance, reconfigurable functionality and future-ready architecture of the Agilent PXA signal analyzer help designers stay ready for whatever may crop up next. These capabilities enable engineers to drive the evolution of their designs—today and tomorrow.
Jeff Owen is a senior product manager for Agilent Technologies’ Microwave and Communications Division. His current responsibilities include serving as a product launch lead for the new, high-performance PXA signal analyzer. Jeff received his BSEE and MBA degrees from Gonzaga University, focusing on communications theory and DSP as well as strategic management and marketing, respectively.