VT Silicon, a fabless semiconductor startup in Atlanta, GA, today announced the industry’s first silicon-based power amplifier capable of meeting the stringent operating requirements of 4G wireless data transmissions. This breakthrough milestone was achieved after 2 1/2 years of privately funded development by using the company’s patented Linearity Enhancement Technology (LET™) to achieve the power, efficiency, and linearity required by today’s battery-powered 4G broadband mobile devices. The use of silicon (Silicon Germanium, or SiGe) instead of the traditional, more expensive Gallium Arsenide (GaAs) allows a significantly lower cost device with a much higher level of integration. The new PA design has been shown to compete effectively with GaAs PAs on key 4G specifications such as EVM, PAE, and ACPR as defined by the WiMAX Forum™ and 3GPP.
Based on the competitive performance demonstrated by the PA, the company has embarked on the next step of creating a fully integrated single chip Front End RFIC initially targeting the WiMAX market, with future versions designed for LTE. The first chip of the family (VFM2500) will be available for testing in the first quarter of 2010 with production targeted at 4Q2010. The initial design will cover the 2.5GHz to 2.7GHz WiMAX band as well as the 2.4GHz WiFi band, and will include the PA, LNA, T/R Switch, and TX and RX filtering and baluns. Other key features include support for transmit antenna diversity, 2×2 DL MIMO, and dynamic bias control via the serial interface for battery life optimization. The chip includes multiple power modes to allow for efficient operation over a wide range of transmit powers, as well as providing efficient operation in WiFi mode. The Front End RFIC is housed in a single 5mm x 5.5mm x 1mm QFN package that requires only two external bypass capacitors, thereby minimizing the external BOM cost and space requirements.
“This breakthrough design allows us to take full advantage of the power of silicon integration to implement very advanced, intelligent functionality that helps us minimize current consumed by the battery. By communicating with a baseband processor via our SPI bus we can re-optimize performance burst-by-burst so that each power level consumes the absolute least current possible while still meeting EVM and mask specifications,” said Michael Hooper, CEO. “In the past it has not been cost effective for RF Front Ends to achieve this level of sophistication. However, by leveraging our patented LET™ technology to implement silicon PAs we now have the ability to create very complex digital & analog control into the Front End RFIC. This is a first in the industry. This new FEIC will reduce the component count of a typical discrete 1×2 WiMAX front end from approximately 50 components to only 3.”
VT Silicon received its Series A funding in April 2007, and Series B funding in October 2008 from California-based Menlo Ventures to take its fundamental intellectual property (LET™) from the test phase to a fully integrated FEIC.