In order to have a good reception, your cellphone needs a powerful signal from wireless base stations which also need high power amplifiers to extend their cover area. Sadly, these amplifiers generate 10 times the power they need to work which means they have a poor 10% efficiency. However, the efficiency record stands at 50% and it was achieved in 2005 therefore it’s worth trying to improve this technology.

A team of researchers from the University of California, San Diego have reported a 58% power added efficiency or PAE for a wireless base station. The average output power was of 42 watts and they also noted a gain of 10.2 decibels for a single-stage WCDMA base station amplifier. Now, thanks to the UCSD researchers, the high-power base stations would need 86 watts of DC power for 50 watts of output power, and I should mention that before there were needed about 500 watts for 50 watts of output power.

The UCSD researchers also managed to improve the linearization of a WCDMA WiMAX base station power amplifier using high-voltage heterojunction bipolar transistors made of gallium arsenide instead of silicon used in most stations, or gallium nitride used three years ago to achieve a 50 percent efficiency rate.

“GaAs HVHBTs are attractive options since they can provide both high voltage and high efficiency and gain over wide dynamic range signals. Having high efficiency over wide dynamic range is critical because in 3G systems, the demand for power varies widely from instant to instant given the wide variety of modern cell phone communications that go well beyond voice calls,” said leader of the team, Donald Kimball.

In order to make the high-voltage heterojunction bipolar transistors work, the researchers used the so-called envelope tracking technology which combines variable high-power signals with the constant DC voltage. This makes the transistor to dynamically adjust the voltage and the heat, and in the same time it allows the amplifier to perform at a rate close to saturation.

Nokia and HuaWei already announced that they are interested in the technology that the researchers from UCSD have reported and hopefully, if it all goes well, the manufacturers will soon implement it and users will have a better reception at their cellphones.