Browsing by Author "Paul D. Franzon, Committee Member"

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90nm CMOS Direct-Conversion Transmitter Design For WCDMA
(2009-03-11) Yang, Xuemin; Kevin G. Gard, Committee Chair; Antonio J. Montalvo, Committee Member; Paul D. Franzon, Committee Member; Maysam Ghovanloo, Committee Member; D. Troy Case, Committee Member
Over the last decade, third-generation (3G) cellular networks have been undergoing tremendous development to meet an increasing demand for better quality and higher speed wireless services. Silicon germanium (SiGe) bipolar CMOS (BiCMOS) has been the dominant process technology for RF transceivers of cellular systems. However, in recent years, there is increasing interest to implement RF transceivers using advanced submicron CMOS technology driven by the demand for high-volume and low-cost solutions. One big challenge for designing a CMOS WCDMA direct conversion transmitter is to meet the demand for both good linearity and good power efficiency. As opposed to constant envelop modulation adopted in GSM system, WCDMA employs HPSK modulation technique which presents better spectral efficiency but results in variable envelop modulation. Hence, linear amplification is required for WCDMA transmitter. Typically, power efficiency is traded for linearity performance. However, for cellular systems, low power solution is highly desirable for maximum usage of battery life. The goal of this research is to design a CMOS WCDMA transmitter with high power efficiency that is comparable to the SiGe BiCMOS counterpart while meeting the tough linearity specification. In this thesis, a third-order intermodulation distortion (IMD) cancelation technique is developed to design a high power efficiency, highly linear operation and large output power transmitter for WCDMA systems. The third-order IMD cancelation approach is realized by using a two-stage driver amplifier, where amplifiers at the two stages amplifier generate opposite distortions and cancel each other. In this work, the nonlinearity of a CMOS common source amplifier is comprehensively investigated to set a solid ground for directing the design of two-stage driver amplifier with third-order IMD cancelation. One big challenge of two-stage driver amplifier with third-order IMD cancelation is how to maintain the third-order IMD cancelation over process and temperature variations. In this thesis, the required condition to realize third-order IMD cancelation is discussed over process and temperature variations, and the design criteria for achieving the third-order IMD cancelation over process and temperature variations are presented.
Circuit-Level Modeling of Laser Diodes
(2003-07-08) Kanj, Houssam; Gianluca Lazzi, Committee Member; Michael B. Steer, Committee Chair; Paul D. Franzon, Committee Member
In all semiconductor laser diodes the thermal, electrical, and optical characteristics are integrally related. In this work, a new approach to the modeling of laser diodes that integrates electrical, optical and thermal effects is presented. Also, it is demonstrated how physical device models based on complex differential equations can be easily implemented in the object oriented circuit simulator f REEDA™. Implementations of a Double-Heterojunction Laser Diode (DHLD) and a Vertical Cavity Surface Emitting Laser (VCSEL) diode are described. Simulations and results for both the DHLD and the VCSEL diodes are presented for DC, transient, and Harmonic-Balance nalyses.
A Methodology for Mapping Networking Applications to Multiprocessor-FPGA Configurable Computing Systems
(2003-07-20) Subramanian, Sivaramakrishnan; Douglas S. Reeves, Committee Member; Winser E. Alexander, Committee Co-Chair; Clay S. Gloster, Jr., Committee Co-Chair; Paul D. Franzon, Committee Member
Configurable Computing (CC) systems use Field Programmable Gate Arrays (FPGAs) to accelerate compute-intensive applications on general purpose processors. Networking applications are typically compute-intensive and require low initiation intervals in addition to small execution times. Network Processing Units (NPU) are integrated multiprocessors that have been optimized for networking applications. Due to their simplified bit-oriented architecture, NPUs exhibit reduced performance when applications require increased processing power per packet. Line-rate processing of complex-operation networking applications such as load-balancing, compression, application firewalls, or intrusion-detection requires a different approach to meet their high performance constraints. These applications can benefit from a methodology that combines the benefits of configurable computing with the multiprocessor features of network processors. Until recently, solutions using multiple processors and FPGA devices were impractical in terms of power, area, cost and development time. Recent advances in Very Large Scale Integration (VLSI) technology have resulted in new high-density FPGA architectures with multiple embedded processors. Such highly integrated architectures enable practical solutions for line-rate processing of complex networking applications. Existing methods of mapping applications to configurable computing systems are limited to architectures with a single general purpose processor and conventional FPGAs. Very little research has been published that addresses mapping of networking applications to multiprocessor FPGA systems. This thesis addresses this problem by proposing a methodology for mapping networking applications to multiprocessor-embedded FPGA systems. It presents an innovative architecture that uses multiprocessor pipelining and interleaving concepts along with configurable computing concepts to create a Configurable Application Pipeline (CAP). CAPillary, an algorithm for generating CAP solutions for a given networking application, is presented along with examples that demonstrate the effectiveness of the proposed methodology.
A MIMO Receiver SOC for CDMA Applications
(2007-12-20) Chen, Tongtong; W. Rhett Davis, Committee Member; Paul D. Franzon, Committee Member; Xun Liu, Committee Chair
Multiple Input Multiple Output(MIMO) technique promises substantial increase of wireless channel capacity by using antenna arrays at both transmitters and receivers. It is one of the key technology to be used in the third generation wireless communication applications and is a current theme of international wireless research. Hardware implementation of MIMO receiver in today's wireless applications has stringent requirements such as high throughput, low power and high performance. This brings the difficulties to carry out the desired ASIC chip which is feasible to current silicon process. In this thesis, we introduce a new System-on-a-Chip(SoC) design for the 3G Code Division Multiple Access(3G-CDMA) MIMO receiver. The SoC chip consists of a space-time equalizer, a MIMO detector and a turbo decoder onto a single chip, which can be configured to handle different modulation schemes including QPSK and 16QAM according to the signal-to-noise ratio(SNR). At low SNR, QPSK modulation scheme can provide lower bit error rate(BER), while at high SNR, 16QAM scheme can have a larger throughput. Sphere decoding algorithm is used for MIMO detection to achieve near maximum likelihood (ML) performance with relatively lower complexity for practical silicon implementation. To improve the system performance further, we implement a turbo decode, which decode the transmitted information bits using the soft decision result from the sphere decoder. Our design can achieve much lower BER than other current MIMO ASICs in the low SNR range. The paper also analyze the trade-off between the hardware complexity and the BER performance of the MIMO receiver using MATLAB fixed-point simulation and hardware synthesis.
Modeling and Design of a Novel Cooling Device for Microelectronics using Piezoelectric Resonating Beams
(2003-12-29) Wu, Tao; Paul I. Ro, Committee Chair; Andrey V. Kuznetsov, Committee Member; Fuh-Gwo Yuan, Committee Member; Paul D. Franzon, Committee Member
As thermal management in microelectronics becomes more and more important in insuring the reliable operation, a novel and effective cooling device by smart materials such as piezoelectric bimorph needs to be developed. Investigation of modeling and design of piezoelectric resonating structures was conducted. A dynamic performance prediction method was proposed to calculate tip deflections at resonances and investigate the effect of finite stiffness bonding layer in piezoelectric bimorph. Considering the product of resonance frequency and dynamic tip deflection as a performance merit, the effects of length and location of the actuators on passive piezoelectric structures as well as the boundary conditions were analyzed for generating acoustic streaming which may be used for cooling microelectronic components. The cooling effects generated by vibrating non-slot and slotted piezoelectric bimorphs were experimentally investigated. A prototype, which is comprised of a piezoelectric bimorph actuator, an aluminum block with commercial cartridge heater served as heat source, four micrometer heads to adjust the gap size between bimorph and heat source, was constructed. Validated finite element analyses were employed to simulate the vibration characteristics including the natural frequencies and mode shapes of the proposed prototype. Setting the operation frequency at the fundamental resonance frequency, the cooling effects were measured by the temperature drops of the heat source above the vibrating bimorph. Electric field applied on the bimorph and the gap between heat source and actuator were adjusted to find out the best cooling result. Heat transfer coefficients between the heat source and vibrating bimorphs were calculated by ANSYS steady state thermal analysis and the lumped energy balance method. Air flow patterns around the bimorph actuator were visualized using particle tracking velocimetry (PTV) as well. The experiments showed that there exists an optimal gap between the heat source and the vibrating bimorph which brings the maximum temperature drop and the cooling effect increases with the electric field strength. The enhancement of heat transfer between the heat source and the non-slot bimorph can be up to 210% with the acoustic streaming generated by the bimorph vibration. The presence of slots in the bimorphs may enhance the mixing of streams outside and inside the channel resulting in an amplified heat transfer performance. However, the number, location and size of slots may influence the vibration characteristics and the formation of swirling streaming in the channel between the heat source and the bimorph. Finally, the heat transfer coefficient of the prototyped cooling device in terms of mean Nusselt number was correlated as a function of streaming Reynolds number. This study may provide useful information on modeling the vibration characteristics of piezoelectric actuators and designing the miniature cooling device utilizing bimorph vibrations.
Numerical and Theoretical Analysis of Beam Vibration Induced Acoustic Streaming and the Associated Heat Transfer
(2004-02-23) Wan, Qun; Paul I. Ro, Committee Member; Andrey V. Kuznetsov, Committee Chair; Paul D. Franzon, Committee Member; William L. Roberts, Committee Member
The purpose of this research is to numerically and analytically investigate the acoustic streaming and the associated heat transfer, which are induced by a beam vibrating in either standing or traveling waveforms. Analytical results show that the beam vibrating in standing waveforms scatters the acoustic waves into the free space, which have a larger attenuation coefficient and longer propagating traveling wavelength than those of the plane wave. In contrast to a constant Reynolds stress in the plane wave, the Reynolds stress generated by such acoustic wave is expected to drive the free space streaming away from the anti-nodes and towards nodes of the standing wave vibration. The sonic and ultrasonic streamings within the channel between the vibrating beam and a parallel stationary beam are also investigated. The acoustic streaming is utilized to cool the stationary beam, which has either a heat source attached to it or subjected to a uniform heat flux. The sonic streaming is found to be mainly the boundary layer streaming dominating the whole channel while the ultrasonic streaming is clearly composed of two boundary layer streamings near both beams and a core region streaming, which is driven by the streaming velocity at the edge of the boundary layer near the vibrating beam. The standing wave vibration of the beam induces acoustic streaming in a series of counterclockwise eddies, which is directed away from the anti-nodes and towards the nodes. The magnitude of the sonic streaming is proportional to ω²A while that of the ultrasonic streaming is proportional to Ω[superscript 3/2]A². Numerical results show that the acoustic streaming induced by the beam vibrating in either standing or traveling waveforms has almost the same cooling efficiency for the heat source and the heat flux cases although the flow and temperature fields within the channel are different. The hysteresis of the ultrasonic streaming flow patterns associated with the change of the aspect ratio of the channel is numerically investigated. Present research is also extended to a cavity which is driven by a vibrating lid. The ultrasonic streaming induced in the cavity reveals some interesting interactions among the primary eddies, which have never been observed in the classical driven cavity problem.