Recent advances in the growth and processing of electronic diamond have provided a glimpse into the potential device performance and applications that this exciting material system can provide. Unique and highly desirable material properties such as large bandgap, high intrinsic mobility and very high thermal conductivity deem diamond the ultimate material for high power/high frequency device realisation. This combined with ultra small feature processing potential, points towards an ultra short gate length FET technology as the obvious choice for the application of such a unique material system. For this work it is proposed that 10nm T-gate diamond FETs be investigated leading to a device technology that can satisfy the expanding demand for high power / high frequency operation. In particular this technology finds application in increasing the source power of Terahertz imaging systems, which currently are of great interest for security and medical imaging applications. This prime goal of the proposed research is accomplishable using high quality diamond material supplied by U.K. based company Element 6 and use of the extensive fabrication and characterisation facilities at the University of Glasgow. In particular, access to the ultra-high resolution capabilities of the recently commissioned Vistek VB6 electron beam lithography tool, provides a direct route to the realisation of such ultra-small dimension devices.

Wireless communication systems require the translation of an information-bearing signal at higher frequencies (such as radio- or mm-wave frequencies) to allow propagation through the wireless medium (the channel). This translation is typically performed in transmitters and receivers that along with the channel form the communication system. In the transmitter, a power amplifier (PA) is used to boost the power of the signal to a level sufficient to overcome the channel's attenuation and arrive with sufficient signal strength at the receiver. Today's best PAs are capable of 60-70% efficiency when used at their maximum output power. This means that about 1/3 of the power is wasted into heat only for the purpose of amplifying at such higher frequencies. Efficiency decreases when reduced output powers are required. Modern communications standards such as 5G generate signals which present a large power variation over time (this is also described by the peak-to-average power ratio or PAPR) and this causes the PA to operate even more inefficiently with values down to 10-20%, instead of the aforementioned 60-70%. Wasting almost 90% of the DC power into heat causes additional demands on the energy supply network which may lead to an increase in carbon emissions. Higher DC power dissipations result in reduced transmitter performance (e.g. less output power and so less coverage), reduced battery lifetime, in additional weight, cost, and size because of the heatsinks and necessary cooling hardware. Heat dissipation causes the electronics within the PA to operate at higher temperatures which are known to degrade the component's reliability (ageing) and change their electrical behaviour. The goal of this project is to radically improve the RF PA efficiency by using a technique called supply modulation (SM). Unlike the 1952's envelope-tracking (ET) method, SM uses a very high-efficiency modulator to generate a number of voltage levels (Vmin, ..., Vmax) that are applied to the drain of the PA. When the RF output power in the PA is high, the PA is supplied with the maximum voltage level and so it operates at maximum efficiency. Vice-versa, when the PA output power is low, a lower voltage level is supplied to the PA drain. This change in the supply results in an efficiency improvement usually in the range of 20-30% (and so in a SM-PA efficiency of 30-50%), but most importantly, it typically reduces the DC power consumption by ~50% for the same output power. Achieving wider and wider bandwidths for high link capacities requires this SM-PA to commutate very rapidly as a consequence of a wideband signal. The current state-of-art bandwidth is ~100MHz for the SM-PA. Achieving 1GHz bandwidth, as required in multi-band and mm-wave PAs, is thus the target of this project. To achieve this, new circuit topologies combined with high figure-of-merit semiconductor technologies will be explored, with the unavoidable hardware imperfections compensated through signal processing techniques such as digital pre-distortion (DPD). The SMPA specifications and top-level design parameters will be agreed between the University of Bristol (UoB)'s team and the project's partners to ensure relevance for industrial applications. This SM-PA is firstly simulated in the SM part, then in the PA, and then co-simulated together as a complete sub-system. The fabricated prototype is then characterized in terms of linearity, efficiency, and power with the latest communication standards. The SM circuit can also be combined with existing PAs as an 'efficiency upgrade'. Results of this theoretical and experimental activity are presented at conferences and published in journals by the UoB team. Public engagement and industry impact is also ensured by the presence of an advisory board. In summary, this project is an adventurous research programme that will re-define next-generation RF transmitters amplifiers and so contribute to UK's leadership in wireless technologies.

Modern surgical techniques, while extremely successful in curing life threatening diseases, can involve large volumes of tissue removal and possibly blood loss, with impacts upon recovery times, risk of infection and, in the longer term, quality of life. Radio frequency and microwave energy can be and is used in surgical systems to treat a vast range of medical conditions, such as benign and cancerous lesions, heart, liver and eye conditions and obesity (microwave assisted liposuction), with beneficial effects including tissue removal, heating, blood clotting and drying. Cancers of the lung, bowel, breast and prostate accounted for almost half (46%) of all cancer deaths in the UK in 2012 and more than 1 in 3 people will be diagnosed with some form of cancer during their lifetime. However, many clinical applications currently remain unrealised, prohibited by technology that addresses the requirements for power generation and application to the treatment site in a separate manner, greatly limiting overall functionality. Existing systems have proven the capabilities of microwaves; now is the time to realise their full potential in surgery. Accordingly, the proposed research is targeted towards optimising surgery to achieve high precision, minimally invasive surgery using targeted, non-ionising microwave and mm-wave energy. Revolutionising treatments for cancer and other diseases, efficacy will ultimately be improved and the side effects or disruption encountered with existing radiotherapy, chemotherapy or surgery reduced. Performed via an antenna, or applicator, keyhole laparoscopic or endoscopic surgery can be performed with minimal risk to the patient. However, the microwave power source is currently over specified to overcome system losses to the treatment site inside the body. Less than 25% of the applied microwave energy reaches the treatment site; the rest wastefully and potentially dangerously dissipated in the cable as heat over traversed regions of the body not targeted for treatment. The opportunity exists to greatly reduce the cost and size of the source. With the advent of high power density microwave semiconductor devices, clinical effects are achievable much more effectively and efficiently by transforming the system architecture and housing the microwave power source at the point of demand - inside the treatment applicator. Low cost commercial devices are capable of providing the required power levels, with chip dimensions of 0.85 x 1.1 mm to provide an incredibly compact solution. In collaboration with the Christie and Creo Medical, microwave developments will target technology that has undergone preclinical studies for bowel conditions. Applicator integration will deliver an operational concept demonstrator for representative tissue model testing. Manufacturing challenges must be solved to integrate the electronics together with complex antenna structures and future manufacturing technologies, such as 3D printing, will be exploited to produce cost effective applicators. The project will enable a clinically driven trajectory of microwave system developments towards compact applicators that will enable confirmation of diagnosis, energy dose calculation, highly controlled and targeted treatment, efficacy assessment and safe exit to prevent seeding, all in a single minimally invasive intervention procedure. It is envisaged that a range of clinical procedures could be enabled in an outpatient environment or within the patient's home that would otherwise have occurred within an operating theatre.

This proposal is a Platform Grant renewal. Our previous grant allowed us to develop the key characterisation facilities and enabled us to understand fully the materials that were the study of the grant. These materials were low loss microwave dielectrics, ferroelectric materials and thin films of these materials. The Platform renewal will build upon some remarkable discoveries that the team, including the key PDRAs, has made over the last 4 years and centre around functional materials for devices operating from microwave to millimetre wave or from MHz to THz. First it is important to explain the Materials Science progress that forms the underpinning technologies that will enable us to use the Platform grant to build new devices. At the heart of microwave devices are resonators that require low dielectric loss or very high Q factor and the target is to aim for very high Q dielectrics. Our previous Platform grant and indeed prior support from EPSRC allowed us to discover very low loss, high Q materials. This culminated in two significant discoveries. 1 First we were able to use low loss resonators as sensors for liquid sensing 2 Second, we demonstrated that by using a very high Q resonator we could achieve maser action at room temperature and in Earth's field - published in Nature 2012. This platform grant will enable us to build upon these discoveries. 1) Advanced Characterisation: In the first theme the aim will be to carry out a series of qualifying experiments to determine the best possible conditions and materials for sensing over the wide range of frequencies available to us (Hz to THz) 2) Microwave and mm wave sensors: The third theme takes the science to application. We will use the resonators for analysis of ions, biomolecules, proteins and cells. The sensitivity of the resonators allows nanolitre quantities to be analyzed very rapidly for possible cancer cell detection in blood and bacteria in water. 3) "UMPF" and "HEP" Cavities: In the second theme we aim to make UMPF (Ultrahigh Magnetic Purcell Factor) and "HEP" (High Electric Purcell) cavities. These are small resonant cavities with a very high Q given the very small mode volume and success here will enable us to improve electron paramagnetic sensing dramatically and enable single cell detection. Success in these new themes for the Platform would represent a remarkable step-change in technology.

The extraordinary increase of wireless data traffic by smartphones and laptops, virtual reality, billions of IoTs or Industry 4.0 infrastructure need 5G, small cell densification and reduction of digital divide. High throughput connectivity everywhere is a fundamental requirement to support the growing data demand and the evolution of future wireless communication market. Affordable wireless networks with fibre data rate are needed. Wireless links with multi-gigabit (Gb/s) distribution at millimetre waves have been demonstrated up to 400 GHz. However, the strong atmosphere attenuation at the increase of frequency and limitations of the present semiconductor-based millimetre wave technology limit their potentiality. E-band wireless links with 2 GHz bandwidth and theoretical few Gb/s are already in the market, but large antenna footprint and low transmission power are probably preventing wider adoption. The portion of the spectrum above 100 GHz includes numerous wide bands which are presently unused, and could support tens of Gb/s, if adequate millimetre wave technology were available. In particular, the D-band (141 - 174.8) has about 28 GHz split in three sub-bands. The DLINK project aims to bring the UK at the forefront of millimetre wave wireless technology through the realisation of the first high capacity link at D-band with unprecedented performance, to provide 45Gb/s, over 1 km range, and with 99.99% availability in ITU rain zone K (typical of UK and Europe). The DLINK system includes a high power vacuum traveling wave tube (TWT) of new generation driven by a novel resonant tunnelling diode (RTD) transmitter with an integrated vector modulator. The system will be demonstrated in Frequency Division Duplex (FDD), with two bands of 10 GHz each to provide about 45 Gb/s data rate. The high performance of DLINK is enabled by traveling wave tubes as amplifiers, with about 10W output power, which is more than one order of magnitude than solid state amplifiers at the same frequency. The TWT working mechanism is based on the transfer of energy from a high energy electron beam, flowing in a waveguide with high level of vacuum, to the electric field generated by the input signal. No D-band TWTs are available in the market. Substantial challenges must be solved for an affordable microfabrication of mm-wave waveguides, due to small dimensions and three dimensional shapes. The transmitter will be an RTD oscillator with very low phase noise to support QAM modulation generated by an on-chip PIN diode vector modulator. The DLINK system includes two transmitters, one for each FDD channel, integrating a RTD oscillator/transmitter, a TWT and an antenna. For the first time, the property of a transmission link with 20 GHz bandwidth above 100 GHz will be investigated by field tests at BT. The DLINK project has a strong industry focus. It is a collaboration between Lancaster and Glasgow Universities with the strategic support of the wireless communication industry full chain, from devices to end users: IQE (semiconductor wafers), Filtronic (mm-wave links), Teledyne e2v (mm-wave TWT), Nokia (system manufacturer), Intel (chip manufacturer), BT (UK main network operator and end user). The high impact of the project will enable new architectures of wireless high capacity networks by mesh of high data rate links at mm-waves. The DLINK project has the ambition to fully contribute to "Connected Nation", one of the four Prosperous Outcomes and to benefit other numerous ambitions of the Prosperous Nation outcomes. DLINK involves researchers and PhD students of two leading research groups and a number of industry partners that will work together for the success of the project, with a long term strategy for future industry exploitation. A particular attention is devoted to growth of talent, improving the gender balance in the millimetre wave technology sector highlighting role models in the Lancaster and Glasgow teams.