Late in 2011, Fujitsu announced the MB86C83, a CMOS PA that has the potential to firmly establish CMOS PAs in UMTS devices and accelerate the acceptance of CMOS PAs overall. The company announced the PA in a Japanese-language press release that may have escaped the attention of many westerners.
The MB86C83 is a triple-band cellphone power amplifier for W-CDMA fabricated entirely in monolithic CMOS. The PA operates in UMTS Band I (1920 - 1980 MHz), Band V (824 MHz to 849 MHz), and Band IX (1749.9 - 1784.9 MHz), three bands used for W-CDMA in Japan. The HSPA-capable PA produces up to 26.5 dBm of linear output power in a 4 mm x 3.5 mm x 0.7 mm footprint package that also houses impedance matching, output power detector and temperature sensor. Fujitsu fabricates the PA with a proprietary EBV (enhanced breakdown voltage) CMOS process developed by Fujitsu Laboratories.
Fujitsu's MB86C83 takes advantage of the inherent integration advantages of CMOS over GaAs, and clearly targets both the CMOS start-ups and the lower-share GaAs players focusing on W-CDMA such as Anadigics, Mitsubishi and Panasonic. Start-ups Black Sand, Javelin and Acco Semiconductor have developed single-band CMOS PAs for W-CDMA, but to the best of our knowledge have not attained any major design-wins yet. The reliability requirements of the OEMs, the perceived performance disadvantages of CMOS, and the fact that these companies are start-ups with no track record of delivery have probably inhibited the penetration of CMOS PAs for W-CDMA to date. The interest among OEMs in highly integrated multiband, multimode PAs that can support both EDGE and W-CDMA, which the GaAs vendors now offer, is probably another factor working against the CMOS startups.
CMOS PAs from Axiom, now part of Skyworks, provide slightly lower power added efficiency than GaAs and LDMOS-based PAs, and these PAs and earlier devices from Silicon Labs seem to have set expectations for CMOS PAs so far. CMOS PAs have gained market share only in low-priced GPRS handsets in which lower battery life between charges isn’t a big concern. Amalfi Semiconductor, another PA start-up, has skipped 3G PAs so far, concentrating on improving the performance and lowering the cost of CMOS PAs for GPRS. The company plans to target the W-CDMA market later after establishing the credentials of its PAs for GPRS.
Fujitsu’s status as top-tier semiconductor vendor coupled with the small footprint and three-in-one integration of the MB86C83 should get the attention of the chipset suppliers and OEMs serving the Japanese market. If Fujitsu’s MB86C83 PA lives up to initial promises, we would expect Fujitsu to launch versions with other band combinations by year’s end, for example Bands I, II and V, and Bands I, III and VIII for the North American and Western European markets, respectively.
Fujitsu hopes to ship at least 1.2 million of the PAs over the first 12 months of production, which started in November 2011 with sample shipments. Small quantity prices started at Yen 350, or about $4.55 at the time of the press release.