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Title: Small signal characterisation and temperature analysis of HBTs and pHEMTs using IC-CAP
Author: Chitrashekaraiah, Sunil
Awarding Body: University of Manchester
Current Institution: University of Manchester
Date of Award: 2007
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With the emergence of multichannel/multimedia communication service, RF and microwave products are being driven by ever increasing demands for higher powers, higher efficiency, lower costs, smaller size, and shorter time-to-market. RF and microwave monolithic ICs with Heterojunction Bipolar Transistors (HBTs) and High Electron Mobility Transistors (HEMTs) as backbones is one of the best solutions that can meet this demand. As the range of applicability of these devices increases it becomes imperative to have efficient and accurate device models which include various effects. In this thesis the small signal characteristics of InGaP/GaAs DHBTs and AIGaAs/lnGaAs/GaAs pHEMTs have been analysed and modelled for the first time using a newly developed automated procedure. The . parameter extractions for HBTs and HEMTs over varying bias and temperature conditions were implemented using Agilent’s Integrated Circuit Evaluation, Characterisation and Analysis Program (IC-CAP). The novelty of this work lies in the simple flow developed which is applicable to any given device over a wide bias, frequency and temperature range. A maturity in the conventional small signal model is presented based on the analysis and this is validated for the RF performance of the fabricated DHBTs and pHEMTs. Emphasis has been made on the temperature analysis and novel results of device parameters are discussed that govern the speed and power handling capabilities of these components. The temperature dependant data is highly valuable when developing temperature susceptible circuits such as power amplifiers, cryogenically cooled low noise amplifiers etc. This data also provides an insight into the material properties that is very important in selecting the right material for a specific application. The physical origin of degradation in performance of the transistor characteristics with temperature is discussed in detail and modelled empirically. For the first time the effect of frequency on the small signal characteristics of these devices is discussed in detail which conventionally is considered to be frequency independent. The developed linear temperature dependent small signal model of the AIGaAs/lnGaAs/GaAs pHEMT is used to design a broadband amplifier operating at 8GHz bandwidth covering bluetooth and wireless applications.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available