David_HallAs today’s wireless handsets continue to support more wireless standards, the components that go into handsets must undergo more testing than ever before. In the old days, it was sufficient to test a GSM power amplifier (PA) by doing a few simple GSM measurements in one or two frequency bands. However, today’s multi-mode and multi-band PA’s require substantially more testing – requiring measurements from GSM to WCDMA to LTE – and in more bands than ever before. Given the increasing number of measurements required for a cellular PA, it’s no wonder that PA manufacturers are continually seeking faster and more cost-effective methods for part characterization.

One cellular PA manufacturer using PXI for product characterization is Triquint Semiconductor. Triquint is an industry leader in high-performance RF solutions for sophisticated mobile devices, defense and aerospace applications, and network infrastructure. Today, TriQuint delivers innovative solutions using GaAs, GaN, SAW, and BAW technologies to organizations around the world.

Next Generation Characterization Test Set
Within Triquint’s product development cycle, one bottleneck to bringing products to market more quickly was the product characterization measurements. With existing rack-and-stack test equipment, thorough characterization of a single part could take up to two weeks – a time that was largely driven by the measurement speed of the test equipment. To address the growing challenge of reducing test time in RFIC characterization, the engineers at Triquint developed a PA characterization test system based on NI PXI, LabVIEW, and NI TestStand. The test bench included the following instruments, illustrated in Figure 1.

• RF vector signal generator
• RF vector signal analyzer
• 8 GHz programmable RF amplifier
• NI PXIe-5122 100 MS/s high-speed digitizer
• Programmable power supply
• Precision source measure unit
• Dual 6x1 26 GHz multiplexer
• Traditional rack-and-stack spectrum analyzer
• External power meter, power supplies
• NI TestStand
• NI GSM/EDGE Measurement Suite
• NI Measurement Suite for WCDMA/HSPA+ 

Figure 1. PXI Test Equipment Used to Reduce Product Characterization Time.

Using NI LabVIEW software, the Triquint engineers updated existing test plans to perform the same sequence of measurements on the new NI PXI test bench. Because the PXI instruments were able to perform individual measurements faster than the rack-and-stack equipment, the test code was configured to use the PXI bench whenever possible, augmenting it with traditional rack-and-stack instruments only as necessary.

PXI Measurement Speed Improvements
By developing a modernized amplifier test system, overall characterization times were shortened from two weeks to about 24 hours. In addition, significant improvements in measurement time were observed for each of the GSM, EDGE, and WCDMA measurement sequences. Figure 2 compares the measurement times and speedup of both the traditional and the PXI test benches.

Figure 2. The PXI test bench performed 6x to 14x times faster for individual measurement sequences.

As a result of using PXI modular instruments, the product characterization group at Triquint semiconductor was able to significantly reduce the characterization time of PA’s without sacrificing measurement accuracy. In addition, the new PA characterization systems were built at the same or lower cost than the original traditional instrument solution.