Fifth-generation LDMOS process boosts amplifier efficiency in W-CDMA base stations
Royal Philips Electronics fifth-generation LDMOS process technology will allow wideband-CDMA (W-CDMA) base stations to break through the 30 percent efficiency barrier for RF power amplifier output stages. That achievement raises W-CDMA efficiency by as much as four percent when compared with LDMOS processes currently in production. Using this technology for W-CDMA base stations, RF power amplifiers can reduce power consumption by more than 15 percent (see the photo).
Fabricated on the company's 0.14-um CMOS production lines, Philips' new LDMOS technology produces RF power transistors with a 0.4-µm size and four-layer metallization. These characteristics yield high values for operating efficiency, gain and linearity. Philips claims to be the first company to have a 0.4-µm LDMOS RF power transistor technology in volume production.
The LDMOS technology suits operation across all frequency bands in the 800 MHz to 2.2 GHz range. The company's first devices will target the UMTS and 2 GHz PCS/DCS bands. One new transistor is the BLF5G22-100, a W-CDMA transistor that offers 17 dB gain, an ACLR5 of -39 dBc, an operating efficiency of 30 percent at an average power output of 26 W, and a peak output power of more than 160 W. These specifications are based on two-carrier W-CDMA operation with 10 MHz spacing and a PAR of 8.5 dB at 0.01 percent probability on CCDF.
The aluminum-copper (AlCu) metalizations used in fifth-generation LDMOS transistors replace the gold metallizations used on Philips' previous-generation devices yet retain similar levels of reliability. Compared to the two-layer Al metallizations used in competitors' devices, these thick and wide AlCu metallizations offer a four-fold increase in reliability and significantly reduce the transistors' parasitics.
Enhanced reliability allows the LDMOS transistors to operate at junction temperatures up to 25 K (degrees Kelvin) higher than conventional devices. At the same time, enhanced transistor design has reduced the junction-to-case thermal resistance to less than 0.5 K/W (degrees Kelvin per watt), reducing heatsinking requirements.
The first fifth-generation LDMOS devices will sample in Q4 2004 with volume production scheduled to start in Q2 2005. For more information, see www.philips.com/rfpower.
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