Teardown Signals Transition from GaAs to CMOS Power Amplifiers In 3G Handsets

Javelin's proprietary 3G CMOS power amplifier architecture includes input matching network, tunable bandpass filtering between each amplifier stage and an output matching network. Plus, it also integrates power regulation, bias and power control circuitry.

Although, working CMOS based 3G RF power amplifiers (PAs) were demonstrated several years ago, the transition from 2G to 3G handsets has not been that easy for CMOS. Concerns over performance have severely limited its progression in the 3G space. However, continued improvements in silicon technology and amplifier architecture have finally enabled CMOS PAs to capture 3G handset sockets. And that shift is being signaled by Samsung Galaxy Appeal.

A recent teardown of the Samsung Galaxy Appeal handset, by ABI Research, shows that it is one of the first mass produced 3G phone to ship with a high performance CMOS PA, designed and fabricated by Javelin Semiconductor. In fact, Javelin’s CMOS PAs are also powering two more Samsung smartphones, namely Galaxy Ace Plus and Galaxy S Duos. Javelin’s director of marketing Robert Wagner, said, 3G mobile handset makers in China are also utilizing Javelin’s CMOS PAs in their 3G handsets, respectively. Without giving the identity, Wagner said that the top mobile handset manufacturer in China is also using Javelin’s CMOS PAs in 3G handsets. As a result, Javelin’s CMOS PAs are now powering ten 3G mobile handsets worldwide.

Until now, according to ABI Research, the gallium arsenide (GaAs) based PAs from incumbents such as, Avago Technologies, TriQuint Semiconductor, RF Micro Devices, Skyworks Solutions, and Anadigics have not felt any real impact of CMOS. But, new products such as the Javelin J5501 (Band I) PA found in the Galaxy Appeal indicate that this performance gap has been narrowed significantly.

Jim Mielke, vice president of engineering at ABI Research, states, “Even though the CMOS PA is over 3x the die area of a typical GaAs PA (3.3 sq. mm vs. 1 sq. mm in the Appeal), the lower CMOS wafer cost, simple packaging and the added digital content with reduced test times allow the CMOS PAs to compete on cost as well as performance.” Mielke went on to add that the market should, “expect single digit market share numbers for CMOS PAs in 2013. The CMOS PA market volumes could be even higher if Qualcomm is successful with their penta-band CMOS PA they are actively presenting now.”

Per ABI Research’s teardown analysis, the product testing of the Galaxy Appeal and the Javelin J5501 provided some key information that is central to this evolving market. The teardown analysis shows that CMOS PAs match GaAs efficiency across all power levels up to 22.5 dBm with an efficiency advantage at low power levels–up to 20 percent low current. In addition, though GaAs PA die are significantly smaller than CMOS equivalents, both GaAs and CMOS PAs can be manufactured for under 40 cents.

According to Javelin, its CMOS PAs are designed to meet the output power, linearity and low noise requirements of the 3GPP UMTS standards while consuming very low current. For that, it incorporates a proprietary amplifier architecture that includes input matching network, tunable bandpass filtering between each amplifier stage and an output matching network. The CMOS PA also integrates circuitry for power regulation, bias and power control (see Figure).

Javelin offers a family of CMOS PAs covering the popular UMTS bands, including Band I (1920 to 1980 MHz), Band II (1850 to 1910 MHz), Band V (824 to 849 MHz) and Band VIII (880 to 915 MHz).

Meanwhile, enhancements to the architecture continue as Wagner sees the CMOS PA trend migrating to 4G LTE devices soon. Efforts are underway to improve peak-to-average output power capability of the CMOS PA in order to meet the peak power requirements of LTE. According to Wagner, Javelin designers have demonstrated that CMOS PA can meet power requirements of 4G LTE. Plus, it can deliver envelope tracking similar to GaAs PA. And narrowband architecture does a good job of filtering environmental noise, noted Wagner. The company is planning to demonstrate 4G CMOS PA sometimes in the second half of next year.

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