Texas-based Black Sand has announced what it claims is the first all-CMOS RF power amplifier (PA) for 3G phones, and has closed a $10m funding round.
The firm claims its amplifier performs as well as GaAs PAs, and is significantly less costly to make.
"There is a fundamentally wide gap between the price of CMOS vs GaAs per square millimetre, 4x would not be an exaggeration." CEO John Diehl told Electronics Weekly. "Our first generation device is not even 2x larger than a 3rd or 4th generation GaAs 3G PA."
Dubbed DST3501, the chip is made on standard 130nm RF CMOS from TSMC.
Black Sand, whose founders were with Silicon Labs' RF team, has overcome the inherent lesser voltage performance of CMOS compared with GaAs using a novel output architecture which shares voltage between multiple transistors.
"Our architecture is stacked transistor and differential, and we have a patented balun transformation network that combines the power of all the transistors and performs transformation at the same time," said Diehl.
The network is partly on the CMOS, and partly within the 3x3mm package.
He claims that using CMOS has also allowed components normally needed around the PA to be brought into the device or done away with. "We can get away with one or two external components." said Diehl. "The leanest GaAs competitor needs six, and most need 10."
According to Black Sand, at 27.9dBm output, device efficiency is 41.7% and adjacent channel leakage ratio (ACLR) is -40dBC.
The investment, the firm's second round, "will fully cover the expense of moving 3501 from sample phase to mass production", said Diehl. "I expect customer volumes to ramp up in the second half of 2010."
The recent round was led by Northbridge Venture Partners and joined by Austin Ventures, bringing the total investment in the company to $18.2m.