Consumer’s wireless communications is requesting ever increasing data rates to feed the tremendous growth of new mobile multimedia applications and the number of people using them. Today, the consumption of high-quality multimedia is no longer constrained to the wired connection of – for example – the living room, but is expected to be available anytime, anyplace. This data traffic can only be provided by extending the wireless communication bandwidths which can only be achieved by moving the frequency bands up to higher frequencies. As a response to this challenge, the 5G standard defines new bands in the mm-wave region. The first band being standardized is situated around 28GHz, where up to 1GHz of RF bandwidth is now available. In the near future, extra bands at even higher frequencies will be standardized, such as around 39GHz, 60GHz, 95 GHz and more to come.
To integrate a 5G transceiver in a battery-operated cellphone, it is important to minimize its power consumption to maximize the battery lifetime. Due to the high operating frequency and the high bandwidth and linearity requirements of the transmitter, the latter is consuming a large portion of the total power budget. It is therefore primordial to develop highly efficient transmitters for 5G communication.
This PhD thesis targets the design of efficient transmitter architectures for 5G mm-wave communication, with an emphasis on linearity and efficiency. Both are linked to each other, as a high efficiency will be needed at a given back off from the maximum output power level, where typically the efficiency is maximal. As the transmitter operates at mm-wave frequencies, beamforming is used to combine the outputs of several power amplifiers and focus them towards the receiver. Here, a clever choice will partition the power budget and certify that the beam is created with little power or linearity penalty.
During this PhD, you will select an optimal transmitter architecture. A starting point will be to analyze known efficiency enhancements techniques such as Envelope Tracking or Doherty. Then you will determine how these are suited for the targeted 5G application.
For optimal performance at mm-wave frequencies, technology is an important parameter. While CMOS is used for the RF transceiver in many consumer-oriented solutions, it may fall short when considering power amplifiers at mm-wave frequencies. Therefore, you will also analyze solutions that use III-V technologies (GaAs or GaN) and select the most optimal technology. Designs will be validated using commercially available III-V technology. Moreover, imec has been working since several years on the co-integration of III-V semiconductors with CMOS. This technology will also be considered, and the unprecedented combination of CMOS and III-V may inspire for innovative circuit design beyond the State of the Art.
Required background: This PhD requires experience and a broad interest in analog integrated circuit design and mm-wave RF design.
Type of work: 10% literature, 20% architectural study, 60% IC design, 10% experimental
Supervisor: Piet Wambacq
Daily advisor: Mark Ingels
The reference code for this position is 2020-092. Mention this reference code on your application form.