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dc.contributor.advisorArslan, Tughrul
dc.contributor.advisorHamilton, Alister
dc.contributor.authorWong, Yan Chiew
dc.date.accessioned2014-11-18T14:16:40Z
dc.date.available2014-11-18T14:16:40Z
dc.date.issued2014-06-30
dc.identifier.urihttp://hdl.handle.net/1842/9656
dc.description.abstractTunability and adaptability for radio frequency (RF) front-ends are highly desirable because they not only enhance functionality and performance but also reduce the circuit size and cost. This thesis presents a number of novel design strategies in DC-DC converters, impedance networks and adaptive algorithms for tunable and adaptable RF based mobile telecommunication systems. Specifically, the studies are divided into three major directions: (a) high voltage switch controller based DC-DC converters for RF switch actuation; (b) impedance network designs for impedance transformation of RF switches; and (c) adaptive algorithms for determining the required impedance states at the RF switches. In the first stage, two-phase step-up switched-capacitor (SC) DC-DC converters are explored. The SC converter has a simple control method and a reduced physical volume. The research investigations started with the linear and the non-linear voltage gain topologies. The non-linear voltage gain topology provides a higher voltage gain in a smaller number of stages compared to the linear voltage gain topology. Amongst the non-linear voltage gain topologies, a Fibonacci SC converter has been identified as having lower losses and a higher conversion ratio compared to other topologies. However, the implementation of a high voltage (HV) gain Fibonacci SC converter is complex due to the requirement of widely different gate voltages for the transistors in the Fibonacci converter. Gate driving strategies have been proposed that only require a few auxiliary transistors in order to provide the required boosted voltages for switching the transistors on and off. This technique reduces the design complexity and increases the reliability of the HV Fibonacci SC converter. For the linear voltage gain topology, a high performance complementary-metaloxide- semiconductor (CMOS) based SC DC-DC converter has been proposed in this work. The HV SC DC-DC converter has been designed in low voltage (LV) transistors technology in order to achieve higher voltage gain. Adaptive biasing circuits have been proposed to eliminate the leakage current, hence avoiding latch-up which normally occurs with low voltage transistors when they are used in a high voltage design. Thus, the SC DC-DC converter achieves more than 25% higher boosted voltage compared to converters that use HV transistors. The proposed design provides a 40% power reduction through the charge recycling circuit that reduces the effect of non-ideality in integrated HV capacitors. Moreover, the SC DC-DC converter achieves a 45% smaller area than the conventional converter through optimising the design parameters. In the second stage, the impedance network designs for transforming the impedance of RF switches to the maximum achievable impedance tuning region are investigated. The maximum achievable tuning region is bounded by the fundamental properties of the selected impedance network topology and by the tunable values of the RF switches that are variable over a limited range. A novel design technique has been proposed in order to achieve the maximum impedance tuning region, through identifying the optimum electrical distance between the RF switches at the impedance network. By varying the electrical distance between the RF switches, high impedance tuning regions are achieved across multi frequency standards. This technique reduces the cost and the insertion loss of an impedance network as the required number of RF switches is reduced. The prototype demonstrates high impedance coverages at LTE (700MHz), GSM (900MHz) and GPS (1575MHz). Integration of a tunable impedance network with an antenna for frequency-agility at the RF front-end has also been discussed in this work. The integrated system enlarges the bandwidth of a patch antenna by four times the original bandwidth and also improves the antenna return loss. The prototype achieves frequency-agility from 700MHz to 3GHz. This work demonstrates that a single transceiver with multi frequency standards can be realised by using a tunable impedance network. In the final stage, improvement to an adaptive algorithm for determining the impedance states at the RF switches has been proposed. The work has resulted in one more novel design techniques which reduce the search time in the algorithm, thus minimising the risk of data loss during the impedance tuning process. The approach reduces the search time by more than an order of magnitude by exploiting the relationships among the mass spring’s coefficient values derived from the impedance network parameters, thereby significantly reducing the convergence time of the algorithm. The algorithm with the proposed technique converges in less than half of the computational time compared to the conventional approach, hence significantly improving the search time of the algorithm. The design strategies proposed in this work contribute towards the realisation of tunable and adaptable RF based mobile telecommunication systems.en_US
dc.contributor.sponsorMinistry of Higher Education Malaysiaen_US
dc.contributor.sponsorUniversiti Teknikal Malaysia Melaka (UTeM)en_US
dc.language.isoenen_US
dc.publisherThe University of Edinburghen_US
dc.relation.hasversionY.C. Wong, N.H. Noordin, A.O. El-Rayis, N. Haridas, A.T. Erdogan, and T. Arslan, "An evaluation of 2-phase charge pump topologies with charge transfer switches for green mobile technology," IEEE International Symposium on Industrial Electronics (ISIE2011), pp. 136-140, 2011.en_US
dc.relation.hasversionY.C. Wong, W. Zhou, A.O. El-Rayis, N. Haridas, A.T. Erdogan, and T. Arslan, "Practical design strategy for two-phase step up DC-DC Fibonacci Switched-Capacitor converter," 20th European Conference on Circuit Theory and Design (ECCTD), pp. 817- 820, 2011.en_US
dc.relation.hasversionY.C. Wong, T. Arslan, A.T. Erdogan, N. Haridas, and A.O. El-Rayis, "Speedy Derivative-Corrective Mass Spring Algorithm for Adaptive Impedance Matching Networks," Electronics Letters, vol. 48, pp. 653-655, 2012.en_US
dc.relation.hasversionY.C. Wong, T. Arslan, and A.T. Erdogan, "Reconfigurable Wideband RF Impedance Transformer Integrated with an Antenna for Multi-band Wireless Devices," Loughborough Antennas & Propagation Conference, pp. 1-5, 2012.en_US
dc.relation.hasversionY.C. Wong, T. Arslan “An Adaptive Impedance Matching Network for Smart Antenna Systems” University of Edinburgh Postgraduate Research Conference, 2012.en_US
dc.relation.hasversionN.H. Noordin, Y.C. Wong, A.T. Erdogan, and T. Arslan, "Meandered inverted-F antenna for MIMO mobile devices," Loughborough Antennas and Propagation Conference (LAPC), pp. 1-4, 2012.en_US
dc.relation.hasversionY.C. Wong, T. Arslan, A.T. Erdogan, and A.O. El-Rayis, “Efficient Ultra-high-voltage controller-based complementary-metal-oxide-semiconductor switched-capacitor DC-DC converter for radio-frequency micro-electro-mechanical systems switch actuation," IET Circuits, Devices & Systems, vol. 7, pp. 59-73, 2013.en_US
dc.relation.hasversionY.C. Wong, T. Arslan, and A.O. El-Rayis, “Adaptive Impedance Tuning Network Using Genetic Algorithm: ITuneGA” NASA/ESA Conference on Adaptive Hardware and Systems (AHS-2013), 2013.en_US
dc.subjectadaptive impedanceen_US
dc.subjectmatchingen_US
dc.subjectSC DC-DC converteren_US
dc.subjectmobile telecommunicationen_US
dc.titleImpedance matching and DC-DC converter designs for tunable radio frequency based mobile telecommunication systemsen_US
dc.typeThesis or Dissertationen_US
dc.type.qualificationlevelDoctoralen_US
dc.type.qualificationnamePhD Doctor of Philosophyen_US


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