Armms RF and Microwave Society
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Conferences

Monday 18th April to Tuesday 19th April 2016 at The Oxford Belfry, Nr Thame

The April 2016 took pace at the Oxford Belfry. The Steve Evans-Pughe prize for the best paper  (sponsored by NI) was awarded to Steve Cripps. The runner-up was David Hand/

VENUE

The Oxford Belfry
Milton Common
Nr Thame
Oxfordshire

Tel01844 279 381
Webhttp://www.qhotels.co.uk/our-locations/the-oxford-belfry/

PROGRAMME CO-ORDINATOR

Jonathan Leckey
MACOM

Emailjonathan.leckey@macom.com

PAPERS

A Digital-to-Analogue Converter Based Envelope Modulator for RF Power Amplifiers

Gavin Watkins
Toshiba

This paper details the design and results of a high efficiency envelope modulator for modulating the supply voltage of an RF power amplifier (PA) with the instantaneous envelope amplitude of the transmitted signal. The modulator is a split frequency design composed of a switched mode power supply (SMPS) for the low frequency content, and a digital-to-analogue converter (DAC) inspired hybrid amplifier for the high frequency. When combined with a 300 MHz RF PA, 65.6% DC-to-RF efficiency is achieved at 18.2 W RF output power with a 3 MHz bandwidth LTE signal.


All-digital Radio Transmitters

Desmond Phillips
Cambridge Consultants

All-digital radio transmitters are being considered as a serious rival to traditional analogue ones because of advances in digital technology. They offer the lure of superior linearity, power efficiency and spectral flexibility. However, one of the big problems is in physically generating the digital symbol stream fast enough (typically at four times carrier frequency) to render the analogue waveform with sufficient quality after filtering. The standard approach of using Bandpass Delta-Sigma Modulators (BPDSM) is difficult to speed up by parallelism because of intrinsic data dependencies. Typical BPDSM solutions compromise the mathematics for simple implementation resulting in poor signal quality and an inflexible output spectrum. Against this background, we propose an alternative approach "Pizzicato" which facilitates a high fidelity (arbitrary frequency) in-band signal. The approach is cost effective and has been mapped to a real-time demonstrator based on an off-the-shelf FPGA.


An Introduction To The Emerging RF Energy Market

Mark Murphy
MACOM, Netherlands
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Creativity in R&D

Jamie Cleaver
Freelance Trainer and Facilitator

Description:  Sir Ken Robinson defines creativity as “the process of having original ideas that have value.”  It therefore seems logical that creativity should play an important role in research and development.   Key fundamental questions are:

1)      How creative are we currently in our R&D activities?

2)      Is there benefit to being more creative in R&D?

3)      How might we encourage creativity in R&D?

This presentation attempts to answer these questions using evidence drawn from case studies, statistics, and personal experience.


Design Techniques and Challenges for RF Silicon

Brendan Foley
Macom, Cork

“There is a continuing trend for wireless building blocks to be integrated into silicon. There are many factors driving this trend, cost, improved silicon performance, the move away from negative supply voltages, enhanced programmability etc. A summary of the current state of the art research and products will highlight the pervasive nature of silicon. However, a focus on the design techniques of several wireless building blocks including VCOs, LNAs, and baluns, will highlight the challenges of the technology, including, lower supply voltages, breakdown, ground inductance, low substrate Er, and others.”


Examination of an L band direct down conversion receiver using latest GSps ADCs

Andrew Glascott-Jones
E2V

Designers of Microwave systems operating in the L band (1 GHz to 2GHz) have traditionally used frequency down conversion techniques employing local oscillators and mixers followed by low speed ADCs.

This article will describe the traditional down conversion techniques and compare their performance with that of a direct down conversion. Applications in the fields of satellite communications, Radar and instrumentation will be highlighted. Future systems employing direct down conversion in these application fields will be proposed. 

The introduction of the next generation of Giga Sample per second (GSps) Analog to Digital Converter (ADC) with best in class performance at above 2GHz input frequency has meant that direct digital down conversion methods can be used which provide greater flexibility and reduced component count.

Designers of Microwave systems operating in the L band (1 GHz to 2GHz) have traditionally used frequency down conversion techniques employing local oscillators and mixers followed by low speed ADCs.

This article will describe the traditional down conversion techniques and compare their performance with that of a direct down conversion. Applications in the fields of satellite communications, Radar and instrumentation will be highlighted. Future systems employing direct down conversion in these application fields will be proposed. 

The introduction of the next generation of Giga Sample per second (GSps) Analog to Digital Converter (ADC) with best in class performance at above 2GHz input frequency has meant that direct digital down conversion methods can be used which provide greater flexibility and reduced component count.


From American Footballs to English Soccer Balls, a Personal Journey in RFPA Matching

Steve Cripps
University of Cardiff

As long ago as 1983, the present speaker proposed that the optimum match for a microwave power device can be deduced from loadline considerations. Simple analysis lead to the construction of load-pull contours that were formed by intersecting Smith Chart circles of constant resistance and conductance. Despite its widespread adoption there remained several questions, most notable the widely observed difference between optimum power an optimum efficiency tuning conditions. Recent work at Cardiff has revealed how contours of power and efficiency can be constructed using rule-of-thumb Smith Chart constructions, which retain the same spirit of simplicity in their theoretical derivation.


GaN Epitaxy for Electronic Applications - an industrial perspective

Trevor Martin
IQE Europe

The rapid growth in the use of GaN for electronic as opposed to photonic applications, is focussed on two distinct markets: one associated with Wireless / Radio Frequency applications (RF) and other Power Control (PC).  Interestingly all of these applications use a similar device the lateral Field Effect Transistor (FET).  However the application space is very diverse and ranges from E and D mode devices operating at ~ 300GHz & ~5 V for mixed-signal and digital logic circuits; RF MMICs, power amplifiers, low noise amplifiers and switches operating at ~ 0.5 - 30GHz and 10 - 50V; and DC/AC power conversion circuits switching at lower frequencies < 200MHz but operating voltages from  200 to > 800V.

From an industrial epitaxy standpoint this diversity creates significant challenges but also enables an understanding of GaN alloy performance across a wide range of operating frequencies, electric fields and substrate types (SiC to Si). In this talk I will review the different requirements and provide a perspective on the epitaxy used.


GaN Technology Applications within Finmeccanica

Merv Haynes
Finmeccanica, UK
The increased availability of  GaN technology over recent years has enabled higher power amplifiers and components but has had a slower take up in military systems. The cost and access of the technology and the performance at the high microwave frequencies has kept this largely in the research domain. Solutions to these barriers are now coming to fruition and this technology is breaking through into products.
 
This paper provides an overview and history of GaN technology application within Finmeccanica Airborne and Space systems Division.
 
The early years used single transistors which provided simple hybrid circuits to demonstrate the practically achievable performance and the positive benefits of this technology. The follow on development, through various EDA programmes (Korrigan and Magnus) plus internal research initiatives, have moved the technology forward into MMIC implementation. This is contrasted against the improvement in availability and performance of COTS transistor components which has kept hybrid microwave solutions alive for military airborne systems.

High Frequency Active and Passives Devices Using GaN on Low Resistivity Silicon

Khaled Elgaid
University of Glasgow

The potential use of GaN HEMTs grown on LR Si for MMIC circuits offers the advantage of cost-effective and large diameter wafers, which make manufacturing costs of GaN-on- LR Si potentially competitive with existing high-resistivity (HR) Si and SiC technologies. In addition, the potential use of this technology in new generation of communications applications using GaN on Si substrates were both Power and RF GaN on the same chip will offer the additional benefit of lower cost.

However, RF substrate coupling effects are the main cause of performance degradation when considering LR Si as a substrate. Therefore, substrate loss suppression is a crucial step towards the industrialization of high-quality interconnects and passive elements using GaN-on-LR Si technology.

The talk will highlight recent progress in developing active devices, transmission media, passive devices and integrated antenna technology for GaN on LR Si MMIC platform. RF performance of the realized devices and transmission media measured up to 325GHz will be presented.


Investigation of Reverse Intermodulation in a VHF RF Power Amplifier: a pragmatic approach

David Hand
Park Air Systems

In Air-Traffic Control Communications, when transmitters are co-located at a single radio site, reverse intermodulation - where signals from multiple transmitters intermodulate in the RF power amplifier of one of the transmitters - is a significant challenge. Although reverse intermodulation can be reduced using circulators and filters to protect each transmitter from its neighbours, there is always pressure to rein in the significant additional costs incurred. A proper understanding of the inherent sources of poor reverse intermodulation performance in an amplifier allows the PA designer to exploit existing aspects of the amplifier topology to yield improvements without adding significant cost. Unfortunately, there is relatively little information on this in the public arena so a series of practical laboratory based experiments have been performed to identify the principal sources of reverse intermodulation in a typical VHF power amplifier.


Materials Development for GaN RF and Power Devices

David Wallis
University of Cambridge

Description: Gallium Nitride (GaN) has been shown to offer significant performance advantages over other semiconductor technologies for specific applications. These include increased efficiency, higher robustness and high voltage operation. After almost 20 years of development commercial GaN devices are now available for both RF and Power device applications.  Despite this, challenges still remain to enable wide spread acceptance of this technology. For RF applications, the preferred substrate for GaN growth is Silicon Carbide (SiC) since it offers a relatively close lattice match, very good thermal properties and can be made semi-insulating (SI). However, the typical cost of a 100mm SI-SiC substrates is >00 and therefore is a significant element in device cost. For power switching applications, large area silicon substrates have emerged as the preferred substrate technology since the wafers are cheap (») and importantly provide compatibility with the Si based processing capability that exists for Si CMOS devices. This presentation will outline some of the materials challenges associated with developing GaN based devices. In particular it will highlight the challenges associated with  GaN on Si substrates for low cost manufacturing of this device technology.


Measurement Benefits of PC-driven VNAs

Craig Stewart
Copper Mountain Technologies

Historically, test and measurement instruments have been developed primarily with their own internal operating systems.  In fact, many late model conventional test equipment devices contain embedded PCs running Windows or Embedded Windows.  Unlike such conventional instruments, modular, or PC-driven instruments contain no operating system.  This architecture sports numerous advantages: it enhances instrument lifetime and stability by avoiding operating system and computer hardware obsolescence; it provides a single step to data purging by powering down the machine; it enables easy sharing of the instrument among users in a lab since all calibration and state files are saved on your PC; and it greatly reduces the size, weight, power, and cost of the instrument for the user. 

In this paper, we describe the benefits of modular test equipment in the particular category of USB Vector Network Analyzers, including increased measurement speed, ease of automation, and enabling of advanced measurement scenarios such as pulsed and high power measurements.


Modern Broadband PA Design Techniques Using Load-Line, Load-Pull and Real-Frequency Synthesis

Ivan Boshnikov
ETL, NI AWR, Modelithics

This paper will describe a systematic approach using load-line, load-pull, and real-frequency synthesis techniques for the design a wideband power amplifier using a Qorvo 30W GaN HEMT.



EXHIBITION

Companies booking two or more delegate places are able to take part in the commercial exhibition that accompanies the conference. Please note: there is a maximum of 20 exhibition tables at each meeting, these are offered on a first come basis. Booking two delegate places does not guarantee an exhibition space, please email exhibition@armms.org to check availability and reserve and exhibition space.


SPONSORSHIP

The Society would like to thank MACOM for sponsoring the April 2016 meeting.

 


CALL FOR PAPERS

Contributions are invited with an emphasis on RF and microwave design, research, testing and associated subjects. An oral presentation will be made at the meeting and a written paper will be required for publication in the society digest, which is distributed to delegates at the meeting. Prospective speakers are requested to submit a title and a short abstract to the technical coordinator (see above) as soon as possible.

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