D.L. Edgar

Bio: D.L. Edgar is an academic researcher from University of Glasgow. The author has contributed to research in topics: Coplanar waveguide & Monolithic microwave integrated circuit. The author has an hindex of 6, co-authored 23 publications receiving 106 citations.

Fabrication of 30 nm T gates using SiNx as a supporting and definition layer

Abstract: A new process has been developed to fabricate 30 nm T gates for high performance metal–semiconductor field effect transistors and high electron mobility transistors. The fabrication of short gate length T gates becomes increasingly difficult as the footwidth of the gate is made smaller and this is particularly true when the footwidth is less than 50 nm. In this process a thin SiNx layer is deposited on the substrate prior to the application of a bilayer of poly(methylmethacrylate)/Shipley UVIII resist. After resist patterning by electron beam lithography the nitride layer is etched at a low bias voltage that causes negligible substrate damage. This process step helps to define the gate footwidth and improves mechanical stability of the gate. The measured gate resistance was 375 Ω/mm.

Coplanar waveguide transmission lines and high Q inductors on CMOS grade silicon using photoresist and polyimide

Abstract: Gold coplanar waveguide (CPW) transmission lines with losses of <0.5 dB/mm at 60 GHz have been produced on CMOS grade silicon substrates using a 15 /spl mu/m thick layer of either photoresist or polyimide. This process, together with an electroplated interconnect technique, has been used to produce spiral inductors on a 2 /spl Omega//cm n-Si substrate with a Q of 15 and L of 1.2 nH at 6 GHz.

A 77 GHz coplanar waveguide MMIC BPSK vector modulator realised using InP technology

Abstract: This paper presents results of a 77 GHz Coplanar Waveguide (CPW) Monolithic MilliMetre-wave Integrated Circuit (M/sup 3/IC) BPSK vector modulator which is, to our knowledge the first demonstration of a CPW-based W-band direct carrier frequency modulator on InP technology. The circuit, which employs a balanced reflection topology, was realised using a 0.12 /spl mu/m InP lattice matched HEMT M/sup 3/IC process. The circuit demonstrates an on-off isolation of greater than 25 dB and 180 degrees of phase shift between its ON states.

CPW Interconnects for MMIC Applications on Low Resistivity CMOS Grade Silicon Using Micromachined SU8 Negative Resist

Abstract: In this work we present measured and modelled RF behaviour of a coplanar waveguide (CPW) fabricated on CMOS grade low resistivity Silicon 2?-cm using a novel micromachined SU8 negative resist interface layer. CPW lines were designed and fabricated on the SU8 interface layer of different thickness from 25 ?m to 125 ?m. An attenuation of less than 0.6dB/mm at 60GHz was achieved. Physical line modelling and E-M simulations were performed to support the experimental results and to determine the SU8 dielectric parameters. Micromachining of CPW structures were also investigated where a reduction in loss by more than 30% was achieved.

Metamorphic GaAs HEMTs with fT of 200 GHz

Abstract: We report the RF performance of 0.12 μm T-gate GaAs based metamorphic HEMTs with a composite In0.53Ga0.47As/In0.30Ga0.70As channel. 2×50 μm wide devices demonstrated an fT of 200 GHz, the highest of any three terminal GaAs based device reported to date. In addition, 2×25 μm devices demonstrated 9.0 dB MAG at 94 GHz showing the W-band capability of GaAs based metamorphic HEMTs. (5 pages)

UWB theory and applications

Abstract: Introduction. UWB Channel Models. Modulation Schemes. Receiver Structures. Integrated Circuit Topologies. UWB Antennas. Medium Access Control. Positioning.

A Planar Gunn Diode Operating Above 100 GHz

Abstract: We show the experimental realization of a 108-GHz planar Gunn diode structure fabricated in GaAs/AlGaAs. There is a considerable interest in such devices since they lend themselves to integration into millimeter-wave and terahertz integrated circuits. The material used was grown by molecular beam epitaxy, and devices were made using electron beam lithography. Since the frequency of oscillation is defined by the lithographically controlled anode-cathode distance, the technology shows great promise in fabricating single chip terahertz sources.

Design and analysis of CMOS broad-band compact high-linearity modulators for gigabit microwave/millimeter-wave applications

Abstract: CMOS broad-band compact high-linearity binary phase-shift keying (BPSK) and IQ modulators are proposed and analyzed in this paper. The modulators are constructed utilizing a modified reflection-type topology with the transmission lines implemented on the thick SiO/sub 2/ layer to avoid the lossy silicon substrate. The monolithic microwave integrated circuit (MMIC) chips were fabricated using standard bulk 0.13-/spl mu/m MS/RF CMOS process and demonstrated an ultracompact layout with more than 80% chip size reduction. The broadside couplers and 180/spl deg/ hybrid for the modulators in the CMOS process are broad-band designs with low phase/amplitude errors. The dc offset and imbalance for the proposed topology are investigated and compared with the conventional reflection-type modulators. The measured dc offset was improved by more than 10 dB. Both BPSK and IQ modulators feature a conversion loss of 13 dB, a modulation bandwidth of wider than 1 GHz, and second- and third-order spur suppressions of better than -30 dBc. The IQ modulator shows good sideband suppression with high local-oscillator suppression from 20 to 40 GHz. The modulators are also evaluated with a digital modulation signal and demonstrate excellent modulator quality and adjacent channel power ratio.

Effect of internal reflections on the radiation properties and input impedance of integrated lens antennas-comparison between theory and measurements

Abstract: This paper presents the effect of internal reflections on the beam pattern and input impedance of integrated lens antennas. A silicon lens was designed and manufactured, and measurements were conducted at a frequency of 100 (impedance) and 500 GHz (beam pattern). A frequency-dependence characterization of the beam pattern clearly showed the existence and impact of internal reflections. The measurements confirmed that most of the frequency variations of the beam pattern could be attributed to internal reflections, as predicted by the model. An on-wafer measurement strategy for determining the antenna impedance at millimeter-wave frequencies is presented. The validity of the model was also proven by an excellent match of the input impedance measurements and predictions. Not only the level, but also the oscillation on the impedance curve was predicted accurately. Initial space qualification was performed in the form of thermal cycling.