J.G. Leckey

MACOM (United States)

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i-10 index

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Co-Authors

Andrew D. Patterson

Pennsylvania State University

J.A.C. Stewart

Intel (United States)

P.J. Tasker

Cardiff University

Amelia Greer

U.S. National Science Foundation

David J. Williams

University of Queensland

Vincent Fusco

Queen's University Belfast

Andrew Alexander

University of Surrey

D. Linton

Queen's University Belfast

M. Demmler

Fraunhofer Institute for Machine Tools and Forming Technology

A.D. Plews

University of Leeds

Cooperative Institutions

Queen's University Belfast

University of Surrey

University of Leeds

Universidade de Vigo

Queens University

Fraunhofer Institute for Applied Solid State Physics

Fraunhofer Society

Queen's University

University of London

King's College London

Author Statistics

Papers

Citation

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Research Field

A study of the effect of envelope impedance on intermodulation asymmetry using a two-tone time domain measurement system

David J. Williams J.G. Leckey P.J. Tasker

An error corrected two-tone time domain measurement system has been developed and combined with a low frequency active source and load-pull system to investigate the effects of all impedance terminations, IF and RF, on the linearity and efficiency of power transistors. Measured data is presented on a HBT biased in class B stimulated by-a two-tone signal while actively load pulling the low frequency IF component.

Linearity

Tone (literature)

SIGNAL (programming language)

Output impedance

Envelope (radar)

Impedance bridging

10.1109/mwsym.2002.1012221

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Citations (60)

A MMIC double balanced diode ring mixer in GaAs

Wong Wei Hwee D. Linton J.G. Leckey

This paper presents a monolithic microwave integrated circuit (MMIC) double balanced diode ring mixer. This chip fabricated in the 0.15 μm pHEMT GaAs process which is offered by WIN Semiconductor. Spiral structure of Marchand balun is used to minimize the chip's size. This mixer design achieves a low conversion loss of 5 to 6 dB and high LO-RF isolation of average 45 dB over the RF/LO bandwidth which is 15-25 GHz and a DC-2 GHz IF. This mixer also obtains good linearity with IIP3 of more than 20 dBm. The chip's size included build in Marchand balun is around 0.75 mm2.

Balun

Gilbert cell

Integrated circuit design

Electronic mixer

10.1049/ic.2011.0218

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Citations (9)

Vector-corrected measurement of an injection locked MMIC oscillator at 5.8 GHz

J.G. Leckey Amelia Greer Andrew D. Patterson S. Drew Vincent Fusco

This paper describes a new technique for measurement of vector corrected injection locking oscillator characteristics. The technique offers improved accuracy over previous measurement approaches and also allows measurement of the nonlinear time domain dynamic load-line of the oscillator. The system developed was used to measure the phase modulation characteristics of a 5.8 GHz injection locked MMIC oscillator and the results confirm the predictions made by injection locking theory.

Injection locking

Modulation (music)

10.1109/euma.1996.337700

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Citations (1)

A STUDY OF THE EFFECT OF ENVELOPE IMPEDANCE ON TIME DOMAIN MEASUREMENT SYSTEM INTERMODULATION ASMMMETRY USING A TWO-TONE

David J. Williams J.G. Leckey P.J. Tasker

An error corrected two-tone time domain measurement system has been developed and combined with a low frequency active source and load-pull system to investigate the effects of all impedance terminations, IF and RF, on the linearity and ,efficiency of power transistors. Measured data is presented on a HBT biased in class B stimulated by a two-tone signal while actively load pulling the low frequency IF component.

Tone (literature)

Linearity

SIGNAL (programming language)

Impedance bridging

Output impedance

Source

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Citations (2)

A 25W X-band GaN PA in SMT package

J.G. Leckey

A single stage X-band (9-10GHz) PA module has been developed using a discrete 0.25um GaN transistor with 4.8mm gate periphery, that incorporates input and output matching via discrete substrates in package. The initial demonstrator module achieves 25W of power under pulsed conditions at 9.5-10GHz with Vds=50V, a peak efficiency of 41% and small signal gain of around 12dB. The PA was assembled in a 6mm overmolded QFN package. The power density and peak drain efficiency are in reasonable agreement with the process pcm performance at this frequency, given output matching losses have to be accounted for. This work demonstrates for the first time the feasibility of prematched GaN transistors and MMIC-like modules in high volume SMT packaging and to a frequency of 10GHz.

10.1109/eumic.2014.6997876

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Citations (5)

Nonlinear MESFET parameter estimation using harmonic amplitude and phase measurements

J.G. Leckey J.A.C. Stewart Andrew D. Patterson M.J. Kelly

This paper presents the use of harmonic amplitude and phase measurements in a new approach to nonlinear modeling of the frequency dispersive MESFET. Optimisation based nonlinear parameter estimation and a novel method for direct extraction of nonlinear dynamic drain characteristics are described Improved performance prediction using this new method is illustrated.< >

MESFET

Harmonic

Harmonic Analysis

10.1109/mwsym.1994.335276

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Citations (12)

Envelope domain analysis of measured time domain voltage and current waveforms provide for improved understanding of factors effecting linearity

IEEE MTT-S International Microwave Symposium digest (2003)

David J. Williams J.G. Leckey P.J. Tasker

A detailed understanding of the factors affecting amplifier linearity can be obtained by performing envelope domain analysis on measured time domain voltage and current waveforms. Analysis of the input and output time varying envelopes provides for a direct observation of amplifier linearization through IF (baseband) source pull.

Linearity

Envelope (radar)

Linearization

10.1109/mwsym.2003.1212636

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Citations (22)

Ultra linear C-band MMIC power amplifiers with 50dbm OIP3

J.G. Leckey Andrew Alexander

Two 4W PA MMICs have been developed which cover bandwidths of 5.5–7.1GHz and 7.1–8.5GHz and which demonstrate OIP3 figures of 50dBm at up to 1W total two tone output power from a bias of 8V, 1300mA. The MMICs were fabricated using a highly linear 0.5um GaAs HFET process and packaged in a plastic molded 6mm QFN package. Interpolation of a comprehensive matrix of two tone load pull data was used to set the design target output and driver stage load impedances over bandwidth for the two stage design. The resulting ratio of OIP3 to P1dB is typically 16dB. A thermal design approach guided by finite element analysis and IR spectroscopy measurement was used. To the authors knowledge this is a significant improvement in OIP3 linearity over any other reported multi-stage MMIC amplifier operating at C band.

Linearity

10.23919/eumc.2009.5296354

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Citations (4)

A 120 watt GaN power amplifier MMIC utilizing harmonic tuning circuits for S-band applications

2011 IEEE MTT-S International Microwave Symposium (2015)

Andrew Alexander J.G. Leckey

The design of a 120 Watt S-band GaN power amplifier MMIC is presented. The amplifier was designed using the 0.25um GaN on SiC process from GCS. At Vds= 40V, this two stage amplifier achieved greater than 135W saturated output power, with higher than 47% power added efficiency and with 22dB gain in the 2.8 - 3.5 GHz band. Additionally mid band output power of 195W was achieved at Vds=50V. This result is the highest power ever reported for a two stage GaN MMIC. The use of input and output harmonic terminations for broadband efficiency enhancement was demonstrated.

Power-added efficiency

Watt

Linear amplifier

Power bandwidth

Harmonic

10.1109/mwsym.2015.7167045

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Citations (15)

A non linear vector corrected measurement system for device and system characterisation

Amelia Greer J.G. Leckey Andrew D. Patterson Vincent Fusco J.A.C. Stewart

This paper describes a vector corrected nonlinear measurement system based around a microwave transition analyser and spectrum analyser. This system can be used to measure intermodulation distortion as well as device output harmonic performance under different drive levels, DC bias and fundamental load impedance conditions. The system can also plot the dynamic load lines during measurement. Three applications of the system will be described showing it's versatility in large signal measurements. Firstly, the system will be used to study harmonic generation in HEMT devices, identifying the causes for harmonic nulls in the second and third harmonics with increasing input power and their direct relation to the output IV curves. Secondly the system will be used to measure the phase modulation behaviour of a 5.8 GHz injection locked MMIC oscillator, and finally the systems use in characterising the IMD performance of an active device in the bias plane is described.

Harmonic

Harmonic Analysis

SIGNAL (programming language)

Distortion (music)

10.1109/hfpsc.1997.651649

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Citations (0)