Selected Research Topics

1. Selected Research Topics • VSEM: Virtual Scanning Electron Microscope • Optwire: Free-Space Cellular Optical LAN • Oakleaf: CMOS Optical Transmitter Driver • High Linearity Mixers for RF & Optical Communications • RENIAC: Reconfigurable Novel Integrated Analogue Computing Cell

2. Virtual SEM • VSEM - Virtual Scanning Electron Microscope • Software teaching and training package • High-performance SEM simulator • Computer-based encyclopaedia of SEM science & operating procedures; • Computer-Based Learning (CBL) module to teach/assess users • Founded on mainstream Internet technologies • Easily distributable • Platform portable • Simulator coded using Java. • Digital filters applied in real-time to captured SEM images emulate SEM imaging capabilities • Encyclopaedia uses Flash and XML • Allows delivery of information via web • Demonstrator has shown proof-of-concept of simulator & encyclopaedia Screenshot from the VSEM simulator (above) Screenshot from the VSEM encyclopaedia (below) For further information about VSEM, e-mail Geoff Martin at: info@virtualsem.com Or look at the VSEM website: www.virtualsem.com.

3. To Wired Network Base station Coverage pattern System architecture Detector flip-chip bonded to driver Receiver optical system Diversity receiver chip Controller IC Chiprack packaging PCB Terminal Cellular Optical LAN: Optwire • Aims • Demonstrating compact low cost optical transceivers for in-building free space data networks. Receiverarray • Receiver • InGaAsP imaging system maps arrival angle at detector • Allows uplink direction to be ascertained • Segmentation reduces detector capacitance • CMOS diversity receiver operates up to 1Gb/s • Transmitter • Multiple array of RCLED emitters • Minimises power transmitted • Allows efficient use of bandwidth • Integrated 150 Mbit/s CMOS driver Transmitterdriver

4. CMOS Optical Transmitter Driver • Pre-distortion lineariser gives enhanced SNR • CMOS integrated device • Fabricated using AMS 0.35 mm CMOS technology • IIP3 improved by 8.9 dB at centre frequency of 700 MHz • SFDR3 improvement of 3.6 dB/Hz2/3at 40 MHz system bandwidth

5. Highly Linear CMOS Mixer for Optical and RF Communication • Non-linearity is a serious bottleneck in RF circuit design • Mixer – a critical component in Communications Systems • Non-linearity potentially affects optical or RF network performance • Mixer should reject harmonics and Intermodulation Distortion (IMD) • Novel approach to linearisation of 2 GHz CMOS Gilbert mixer • Based on Volterra Series Analysis • Simulations indicate: • Gain 6dB, SNR 12dB • IIP3 improvement: 10dBmcf. standard Gilbert mixer • Target technology UMC 0.18 RF/MM CMOS Process

6. Reconfigurable Novel Integrated Analogue Computing Cell • Objective • Exploit recent developments in standard VLSI processes & techniques, cheap programmable analogue computers can be conceived • Overall Architecture • Executes both Sequential & Parallel programs • Basic Blocks are • Program Control Element (PCE) • Data Control Element (DCE) • Arithmetic Processing Unit (APE) • Differential Processing Unit (DPE) • Computing Architecture • Solves mathematical problems by attacking it usinga swarm of small and inexpensive computing cells. • Computes using physical analogues instead of mathematical algorithms