LONDON RF front-end specialist and foundry services provider Triquint Semiconductor has started sampling high-voltage gallium arsenide (GaAs) power amplifier transistors it claims substantially increase the efficiency of 3G cellular base stations, leading to meaningful energy savings.
Triquint (Hillsboro, Ore.) will be demonstrating the first device in the series at the European Microwave Week exhibition that starts on October 9 at the Messe Munchen, Germany.
TriQuint said it tested the first of the HV-HBT amplifiers in a design commonly used by base station amplifier manufacturers that pairs devices in a ‘Doherty’ configuration. Used in this manner, the devices delivered an efficiency level of 57 percent, surpassing the efficiencies available using either conventional laterally-diffused metal oxide semiconductor (LDMOS) transistors or more expensive gallium nitride (GaN) devices.
"GSM system amplifiers do not require linear operation, and their efficiencies have traditionally been much higher than amplifiers for 3G systems. Network operators that have deployed 3G systems in the past few years have seen a dramatic increase in OPEX costs related to electricity," said Mike Sanna, TriQuint Semiconductor Vice President of Network Products. "Those operators have gone back to the base station OEMs and amplifier companies with aggressive efficiency goals for existing 3G and next-generation 4G systems to get those costs back under control."
He added TriQuint's HV-HBT transistors would provide a significant "step-function" improvement in amplifier efficiencies.
Sanna said one of the company's (un-named) lead customers reported up to a 10 point increase in amplifier efficiency when using the TGH2932-FL devices.
How much new amplifier design will save network operators depends on several variables including the cost of electrical power in a given area, what cooling systems are employed by the base station manufacturer, and other factors.
Triquint says a good way to illustrate the savings is to consider that for a 50W average power WCDMA amplifier design, the transistors in the company's latest devices create only about 38 Watts of waste heat. LDMOS transistor-based amplifiers used in 3G systems today generate as much as 70 Watts of waste heat. The TGH2932-FL amplifier is said to reduce waste heat by nearly 50 percent.
The immediate opportunity, according to Sanna, is to realize overall savings in existing systems, which will generate less waste heat, reduce air-conditioning expense, cut heatsink size, and require fewer cooling fans.
"The longer term opportunity is the potential to eliminate the ground based amplifier in exchange for a tower top amplifier. That would result in a much more dramatic reduction in both energy consumption and equipment cost," Sanna added.