The Kynix Blog - Amplifiers

A new highly efficient power amplifier for electronics could help make possible next-generation cell phones, low-cost collision-avoidance radar for cars and lightweight microsatellites for communications.Fifth-generation, or 5G, mobile devices expected around 2019 will require improved power amplifiers operating at very high frequencies. The new phones will be designed to download and transmit data and videos faster than today's phones, provide better coverage, consume less power and meet the needs of an emerging "Internet of things" in which everyday objects have network connectivity, allowing them to send and receive data.Power amplifiers are needed to transmit signals. Because today's cell phone amplifiers are made of gallium arsenide, they cannot be integrated into the phone's silicon-based technology, called complementary metal-oxide-semiconductor (CMOS). The new amplifier design is CMOS-based, meaning it could allow researchers to integrate the power amplifier with the phone's electronic chip, reducing manufacturing costs and power consumption while boosting performance."Silicon is much less expensive than gallium arsenide, more reliable and has a longer lifespan, and if you have everything on one chip it's also easier to test and maintain," said Saeed Mohammadi, an associate professor of electrical and computer engineering at Purdue University. "We have developed the highest efficiency CMOS power amplifier in the frequency range needed for 5G cell phones and next-generation radars."Findings are detailed in two papers, one to be presented during the IEEE International Microwave Symposium on May 24 in San Francisco, authored by former doctoral student Sultan R. Helmi, who has graduated, and Mohammadi. They authored another paper with former doctoral student Jing-Hwa Chen to appear in a future issue of the journal IEEE Transactions on Microwave Theory and Techniques.The amplifier achieves an efficiency of 40 percent, which is comparable to amplifiers made of gallium arsenide.The researchers created the new type of amplifier using a high-performance type of CMOS technology called silicon on insulator (SOI). The new amplifier design has several silicon transistors stacked together and reduces the number of metal interconnections normally needed between transistors, reducing "parasitic capacitance," which hinders performance and can lead to damage to electronic circuits."We have merged transistors so we are using less metallization around the device, and that way we have reduced the capacitance and can achieve higher efficiencies," Mohammadi said. "We are trying to eliminate metallization between transistors."The new amplifiers could bring low-cost collision-avoidance radars for cars and electronics for lightweight communications microsatellites.The CMOS amplifiers could allow researchers to design microsatellites that are one-hundredth the weight of today's technology. 

MUNICH—The next generation of mobile radio networks, called AA, will offer the platform for innovative applications requiring extreme short latency times and / or high data rates up to 10 Gbps. Fraunhofer IAF (Freiburg, Germany) has developed one of the building blocks required to roll out AA networks: An integrated circuit for power amplifier transistor implemented in gallium nitride technology. The specific structures on the chip enable base station designers to run the device at relatively high voltages which translates into higher transmitting power than usual. In the related project Flex5Gware, Fraunhofer IAF is already testing prototypes of the device at frequencies to 6 GHz. In such applications, the energy demand depends on the transmission bandwidth. Every bit transmitted requires a certain, constant amount of energy, explains Quay. Since AA will allow 200 times higher bandwidths compared to today’s commercial mobile radio infrastructure, it is necessary to significantly improve the energy efficiency of semiconductor components used for the transmission of 5G high-bandwidth signals. The power amplifier of the Fraunhofer IAF transmits at a frequency of 5.8 gigahertz. These frequency is needed for the new 5G mobile radio standard. The centrally placed gallium nitride (GaN) semi-conductor circuits are the central part of the packaged power amplifier. (Photo & caption: Fraunhofer IAF) Beyond innovative semiconductors, the scientists also are using measures like highly directional antennas to increase the energy efficiency. Being a by-product of metal processing Gallium is widely available. The success of white and blue LEDs which also contain GaN contributed significantly to make the production of GaN as affordable as it is today. The result is that today the energy savings a GaN device can achieve throughout its operating life time exceed the higher manufacturing cost of such devices in comparison to silicon.