From bricks to LTE: mobile phone technology 

20 May 2016

Dr Gary Hau Yan Kit (Croucher Scholarship1994) still remembers seeing the first generation of "brick style" mobile phones being used in Hong Kong, while he was a student in Kowloon Technical School and it inspired a lifelong fascination with electronics and wireless technology.

While obtaining his degree in general electronic engineering at City University, Hong Kong, he asked a visiting professor from England about the best places to study radio communications and Leeds University was suggested. He obtained his MSc there but admits he was “very naive” about the size and potential of the global mobile communication industry and did not regard it as a potential part of his future profession.

“In Hong Kong there is no strong electronics industry, so I was thinking more about an academic career,” he says.

After his MSc in Leeds, Hau decided to take a “gap year” from full time education, so he returned home and worked for SmarTone as an engineer responsible for radio network planning and antenna cell site selection for their new cell networks being established in the city. It meant visiting the rooftops of many high-rise buildings but it gave Hau the invaluable hands-on experience of a real mobile network that he could never find in textbooks and his manager was very supportive. “David Turkington was the engineer at SmarTone who mentored me and brought me into the world of wireless connectivity, ” remembers Hau.

Research and Development 

Dr Gary Hau

Hau successfully applied for a Croucher scholarship to complete a PhD at Leeds, focused on multicarrier microwave amplifiers for cellular communications. This gradually led him towards the world of product development engineering in the rapidly evolving and highly competitive field of mobile communications. This RF amplifier technology touches all our lives every day as they form an integral part of the estimated seven billion mobile phones currently in use around the globe.

Every cell phone in the world has what is called the radio-frequency (RF) front-end module (FEM) which broadly consists of a power amplifier, filters, and switches. It is this front-end which allows the cell phone to transmit to and receive signals from a cell phone tower and it represents a market estimated to be worth over US$5.5 billion annually.

Not surprisingly, Hau was not short of job offers after his PhD but his move towards industrial product development was a “gradual process”.

After a positive experience undertaking industrial research and development at NEC in Japan, which was more “R&D focused than product focused”, Hau says he found the industrial environment refreshing.

“It was great to have a taste of what the real world was like,” he says but still thought this was experience that would help with an academic career. He then moved to the USA in 2001 and accepted a position with Raytheon that allowed him to specialise in the development of RF power amplifiers for FEMs using GaAs (Gallium Arsenic) semi-conductors for commercial mobile phone applications.

“I found that I enjoyed the intensity and dynamic of product development and this work was specific to FEMs in cell phones,” says Hau and it has become his field of expertise with many patents to his name and many research papers published in IEEE journals/conferences on the subject.

Hau explains that it is the power amplifier which is the critical component in achieving the required signal quality and integrity allowing users to download music, images, or movies and GaAs became the technology of choice for RF/microwave power amplifiers used in mobile phones. Linear amplification is essential and the volumes required if the development is successful are potentially huge.

Technology used worldwide

While working at Anadigics, which he joined in 2007, one of the production staff told him that over 60 million units of one of the products Hau had developed had been shipped, all delivered to major mobile phone OEMs within a two year product life cycle.

The advent of LTE (Long Term Evolution which is a 4G wireless broadband network) meant that instead of there being two or three frequencies bands used in the world, every country had its own band. Because of this, the number of frequency bands became “mind boggling”, which set new challenges for engineers. Now, a huge multitude of RF amplifiers had to be squeezed in to one tiny handset so that it would function while roaming the world.

“Now product development is all about integration; trying to combine 20 or 30 components into one compact unit,” explains Hau. Signal quality, compact circuit design, and power efficiency are the main design drivers.

Every time someone downloads or streams a high definition Hollywood movie onto their tiny Smartphone in a remote corner of the world within a few seconds, it represents a minor scientific miracle and Hau is part of that elite group of product developers who helped achieve it.

Dr Gary Hau Yan Kit attended Kowloon Technical School and received his BEng with first class honours in Electronic Engineering from the City University of Hong Kong in 1992, and MSc with distinction in radio communications and high frequency engineering, from the University of Leeds, UK, in 1993. Hau received his PhD degree in electronic and electrical engineering from the University of Leeds in 1998, where he was a Croucher Foundation Scholar. After completing his PhD, Hau took up a research position at NEC Central Research Lab in Shiga, Japan. He was involved in advanced development of GaAs pHEMT and HBT power amplifier MMICs and modules. In 2001, he moved to the USA and joined Raytheon Co as a senior design engineer. Since then has remained on the cutting edge of product design and development of GaAs HBT power amplifier and RF front-end modules primarily for 3G/4G mobile handset applications for leading companies in the field. From 2003-2007, he was with Fairchild Semiconductor, in 2007 he joined Anadigics and in 2015 took up his present position as senior staff design engineer at Qualcomm. Apart from successful product development achievements, Hau is still very active in research and has published papers in various IEEE journals and conferences and has received 12 US patents related to his product development work.

To view Dr Hau’s personal Croucher profile, please click here.