RFMD moves GaN-based PAs closer to market
The company has successfully grown, fabricated and packaged GaN power transistors achieving 28 W performance with CW operation at 20 V. These GaN power transistors are fabricated from RFMD s current 0.9-micron process and exhibit 10 dB of linear gain. The transistors were used to develop 20-W CW power amplifiers for UMTS applications.
RFMD also demonstrated 7 W wideband GaN PAs designed for DCS (1800-1880 MHz), PCS (1930-1990 MHz) and UMTS (2110-2170 MHz) wireless infrastructure applications. The PAs exhibit 11 dB of gain at 20 V operation, with gain slope of +/- 0.2 dB over the entire range and better than +/- 0.1 dB over the DCS and PCS bands.
By exhibiting flat gain over a broad frequency range, the GaN PAs enable a single power amplifier solution over DCS, PCS and UMTS wireless infrastructure bands. The matched power amplifier exhibits an output return loss of -12 dB over the band with a typical input return loss of -11 dB at midband.
Jeff Shealy, VP of the infrastructure amplifier product line at RFMD, said, "The advantages of GaN are clearly demonstrated in the broadband power and gain performance of these matched amplifiers. This wideband performance is extremely difficult to achieve using semiconductor technologies that are commercially available today."
Commercial production
During the current quarter, RFMD delivered packaged engineering samples of the 7 W wideband GaN PAs to leading wireless infrastructure OEMs, thereby providing early access to advanced technologies for next-generation systems.
"We currently anticipate supplying higher performing wideband GaN PAs, with higher power and higher gain, during the September 2003 quarter," added Jeff Shealy.
RFMD achieved these results using its vertically integrated GaN facility in Charlotte, NC (formerly RF Nitro Communications), which incorporates materials growth, device fabrication, packaging, design, reliability and test operations. RFMD s GaN materials are grown on both SiC and sapphire substrates using a patented multi-wafer four-inch system.
RFMD currently plans to migrate GaN commercial production to its high-volume wafer fab facilities located in Greensboro, NC.
Milestones
William Pratt, chief technical officer of RF Micro Devices, said, "We re very enthusiastic about achieving these milestones in GaN power technology, which we believe demonstrate our technology leadership and our ongoing commitment to commercializing the most promising future semiconductor technologies. We believe GaN can conceivably lower the overall cost of wireless base stations and thereby prove to become a disruptive and revolutionary technology in the wireless infrastructure space."
"GaN is a wide bandgap material that can withstand high operating voltages and can operate at high frequencies with high power densities. These characteristics make GaN devices ideal for 2.5G and 3G basestation PAs and provide GaN with competitive advantages over silicon LDMOS, the primary technology in use today.
"RF Micro Devices commercialized the first GaAs HBT PAs for cell phones; this technology displaced all other competitive technologies and is now the dominant technology for PAs used in cellular/PCS handsets. We believe that GaN has the same potential to be adopted as the process technology of choice for basestation PA applications. If this occurs, we expect to be well-positioned to substantially increase our sales into this large, high margin market with our proprietary GaN devices," added Pratt.
