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A simple procedure for extracting parameters of a bias-dependent trap model for GaN and GaAs is presented. The extraction is achieved based on a mapping of the steady-state trap-centre potential for a representative range of the bias voltages. The circuit model of trapping is verified in the process. The time constant for emission is also extracted. It is demonstrated that the model is able to predict...
A procedure for the extraction of a trap model is applied to an AlGaN/GaN-on-SiC HEMT. The trap model is then used in the extraction of a nonlinear device model. The resulting model accurately relates dc I–V with nonlinear behaviour which is crucial for accurately predicting the load-pull measurements. This modeling procedure can be integrated into a modelling/design flow enabling accurate prediction...
This paper presents the performance of a first pass design W-band low noise amplifier MMIC, based on coplanar waveguide (CPW) technology, and utilising 100-nm gate-length GaAs pseudomorphic power HEMTs. With a chip size of less than 1.4 mm2, this two-stage LNA achieves an average small signal gain of 12 dB between 80 and 100 GHz. The measured noise figure averages 5 dB up to 94 GHz. To the author...
The contributions of gate-connected and source-connected field plates to extracted device capacitances (gate-source, gate-drain and drain-source capacitance) are assessed during the development of an AlGaN/GaN-on-SiC HEMT model. The capacitances due to the presence of a gate field plate are observed to be intrinsic in nature, while those associated with a source-connected field plate can be regarded...
A simple thermal model is presented to estimate the junction temperature in multi-finger GaAs and GaN high electron mobility transistors (HEMTs). The model is implemented in SPICE by treating heat flow as analogous to the flow of electric current. The model enables a comprehensive study of different layout possibilities for devices. Results from 3D Finite Element Model (FEM) simulation and from Gate...
A GaAs pHEMT radio chip-set, consisting of receiver, up-converter and power amplifier, for E-band applications demonstrates excellent conversion gain, linearity and output power over the entire 15 GHz bandwidth of the European Telecommunications Standards Institute (ETSI) E-band specification. The receiver's measured gain is 12 dB with an image rejection exceeding 10 dB, an IIP2 of 17 dBm and IIP3...
A GaAs pHEMT frequency doubler, a quadrupler and a power amplifier for E-band applications have been demonstrated to achieve useful output power and power added efficiency (PAE) over a wide bandwidth. The doubler and quadrupler circuits include medium power amplifiers to increase their gain and output power. The doubler has a measured output power greater than 15 dBm over the entire 15 GHz bandwidth...
A Q band doubler and a self-biased V band doubler are presented. The Q band doubler has an output power of 18 dBm and a PAE of 14% which is the highest PAE reported to date at this frequency to the authors' knowledge. The V band doubler produces 16 dBm near its band centre. The doublers are key subcircuits for a Q band receiver with 11 dB gain, IIP3 of 5 dBm and noise figure of approximately 3 dB,...
A small-signal model of the intrinsic region of a microwave FET that considers four capacitance terms is examined. Four reactive terms in the model are required to describe four imaginary Y -parameter terms. The addition of a fourth capacitance rather than a channel resistance or delay term enables extraction of dispersion-free parameters, better consistency with a large-signal model and better scaling...
A HEMT model is proposed that correctly isolates the access metallization from the intrinsic device to give linear scalability. The model uses a distributed network of intrinsic unit cells composed of lumped elements. The topology of these networks is determined such that a scalable set of parameters is obtained. The parameters for the intrinsic and extrinsic parts of the transistor have been extracted...
A GaAs low-noise amplifier (LNA) is designed with first-time success using a technique for HEMT modelling which divides the device into intrinsic gate fingers embedded in an analysable metal structure. The gate finger is characterised by de-embedding metallisation from a standard test structure. The device is then re-built, with any geometry or layout that the foundry allows, and modelled by electromagnetic...
The aim of this work is to develop a scalable small signal HEMT model. We propose a general intrinsic model “unit cell” to build larger transistor devices according to our need and model the metal according to individual geometry using a lumped element network. The challenge we address is extraction of this network from measurement. The parameters of the intrinsic part of the transistor have been...
Operating channel temperature has an important influence on the electrical performance and reliability of GaAs FET amplifiers but this parameter is difficult to determine experimentally or analytically. Simplified closed-form and numerical models are commonly used although both are subject to errors in the case of sub-micron heat sources surrounded by epitaxial layers. Some assumptions about the heat...
Operating channel temperature has an important influence on the electrical performance and reliability of GaAs FET amplifiers but this parameter is difficult to determine experimentally or analytically. Simplified closed-form and numerical models are commonly used although both are subject to errors in the case of sub-micron heat sources surrounded by epitaxial layers. Some assumptions about the heat...
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