A PA's current draw is directly related to its efficiency, and generally the vendor that has produced the highest-efficiency PA has won the market's allegiance. Javelin says its CMOS power amp can attain 40 percent efficiency in high-power mode and 28 percent at mid-power. The 40 percent figure is on a par with the number for GaAs PAs, but the Javelin engineers expect to improve on the JAV5001's efficiency performance in subsequent designs.
If the part takes off, Javelin might be in a good position to build on its momentum through further integration. With most key handset components already rendered in CMOS, it's easy to envision how a CMOS PA could be integrated with other devices to provide higher performance, lower cost and smaller size. Obvious places to start would be duplexers and couplers. But the voltage swings that occur in a PA would make it more difficult to employ the finer line widths associated with transceivers and basebands.
"With this first PA, we only integrated the blocks needed to match the functionality of existing PAs while improving performance. We wanted to enter the market with a part that could easily be adopted into existing platforms," said Fluke. "The big integration comes later, when we work closely with the handset guys and they tell us what they want integrated."
The JAV5001 requires only two external components for supply decoupling and supports a single connection to the battery, thereby reducing the bill-of-materials cost, according to Javelin.
The company further touted its device's low noise, which it said would let handset designers reduce the associated cost of the duplexer or eliminate a transmit surface acoustic wave (SAW) filter, at a savings of 10 or 20 cents.
Javelin has competitors in the CMOS PA space, but none seems to be as far along in the design, at least with a part that's able to achieve the specs of the JAV5001.
Axiom had a 2.5G device that used what it called a distributed active transformer (DAT). The distribution concept helped eliminate the potential for breakdown voltage. But Axiom wasn't able to achieve the efficiency that handset makers required. Skyworks acquired Axiom in May.
Market watchers had thought Black Sand Technologies would be the first to deliver a 3G CMOS PA. Indeed, Black Sand has demonstrated the technology, but only with a preproduction part.
"At first, we focused on hitting the high efficiency, high linearity and high output power all at the same time," said Jim Nohrden, vice president of marketing at Black Sand. "We've demonstrated that, showing performance that matches GaAs, [with] 40 percent efficiency. So we proved we could build the engine. Now we have to do the body."
Nohrden said Black Sand would deliver a production part sometime this year. What's left is to wrap a standard interface around it and do the qualification work necessary to get the part into production, including setting the test limits.
Black Sand announced just days ago that it had acquired a patent portfolio related to CMOS power amplifiers from Silicon Laboratories.
Handset designers can expect the first CMOS PAs to be on a par with GaAs competitors in terms of cost. In lots of 10,000, Javelin's JAV5001, which complies with the 3GPP specifications for W-CDMA and HSPA, will sell for $1.45. The part is housed in a 3 x 3-mm package.
Plans are under way at Javelin for a second-generation CMOS power amp that will operate across multiple bands.