International Telemetering Conference Proceedings / October 23-26, 2000 / Town & Country Hotel and Conference Center, San Diego, California / Spectral sidelobes of QPSK, OQPSK, IJF-OQPSK, and SQAM modulated signals after nonlinear amplification are compared. It is known that OQPSK has lower spectral sidelobes than QPSK. However, in the presence of frequency selective fading, a decision-feedback adaptive equalizer is able to equalize the QPSK signal but not the OQPSK signal. By using phase pre-distortion on the OQPSK waveform before nonlinear amplification, not only is the adaptive equalizer able to equalize this signal, its spectral sidelobes are also reduced. Simulations are presented to confirm these results.

ITC/USA 2011 Conference Proceedings / The Forty-Seventh Annual International Telemetering Conference and Technical Exhibition / October 24-27, 2011 / Bally's Las Vegas, Las Vegas, Nevada / New developments in miniaturized integrated film bulk acoustic resonator (FBAR) filters and low noise amplifiers have resulted in the possibility of extremely small integrated antenna, filter, and low noise amplifier subsystems for use in airborne telemetry (TM) systems. This paper gives examples of a new development in airborne GPS antennas using an integrated band pass FBAR filter and low noise amplifier. Data is also included on the example antenna in a GPS/TM system.

This paper outlines design considerations and implementation details of full swing and of partial swing SRAM arrays. Comparisons between the two methods based on performance, power, and noise rejection are then presented. Finally, a decision matrix will be provided that selects the better topology based on varying design constraints. / text

<p>The electrical interface to neural medical devices is researched from three perspectives, namely, the electronics within the device, the electrodes on the device, and the electromagnetic fields around the device. </p><p>A Brain-Machine Interface may allow paralyzed patients to control robotic limbs with neural signals sensed by fine wires inserted into the brain. The neural signals have an amplitude under one millivolt and must be amplified. A totally integrated amplifier is designed, manufactured, and characterized. The amplifier is fabricated in a standard half-micron CMOS process without capacitors or resistors. Two application issues not previously addressed are solved. First, the topology of the amplifier is shown to be less sensitive to long-term drift of transistor parameters than the standard topology. Second, a neural signal corrupted by 10 millivolts of powerline interference can be recovered. The amplifier has a gain of 58 dB, a bandwidth of 750 to 14k Hz, power consumption of 180 uW, and noise of 1.5 uV RMS. The design techniques proven in this amplifier are suitable for clinical Brain Machine Interfaces.</p><p>An implanted electroencephalogram (EEG) recorder may aid the diagnosis of infrequent seizure-like events that are currently diagnosed, without proof, as epilepsy. A proof-of-concept study quantifies the electrical characteristics of the electrodes planned for the recorder. The electrodes are implanted in an ovine model for eight weeks. Electrode impedance is less than 800 Ohm throughout the study. A frequency-domain determination of sedation performs similarly for surface versus implanted electrodes throughout the study. The time-domain correlation between an implanted electrode and a surface electrode is almost as high as between two surface electrodes (0.86 versus 0.92). EEG-certified clinicians judge that the implanted electrode quality is at least adequate and that the implanted electrodes provide the same clinical information as surface electrodes except for a noticeable amplitude difference. No significant issues are found that invalidate the concept of an implanted EEG recorder.</p><p>Transcranial stimulation may treat a multitude of neural and psychological illnesses. The stimulation may have higher repeatability and lower patient effort if an implanted device provides the stimulation. The shape of the device, 300 mm long by 1 mm in diameter, is unlike any present implanted device. Five techniques that deliver energy to the device are analyzed using computer simulations. The electrode for the techniques that employ an electric field to deliver the energy is a new design that exploits the anatomy of the scalp and skull. The electric field techniques deliver energy that is likely suitable for some stimulation protocols but not for all. The techniques that employ a magnetic field deliver more than the energy required, especially if the shape of the coil that creates the magnetic field is automatically optimized. However, the magnetic-field techniques heat the brain; the electric-field techniques do not heat the brain. This research validates the new delivery concepts and justifies future research.</p> / Dissertation

This thesis is shown the implementation of the linearization techniques such as feedforward and pre-distortion feedback linearization to suppress the optical components nonlinearities caused by the fibre and semiconductor optical amplifier (SOA). The simulation verified these two linearization techniques for single tone direct modulation, two tone indirect modulation and ultra wideband input to the optical fibre. These techniques uses the amplified spontaneously emission (ASE) noise reduction in two loops of SOA by a feed-forward and predistortion linearizer and is shown more than 6dB improvement. Also it investigates linearization for the SOA amplifier to cancel out the third order harmonics or inter-modulation distortion (IMD) or four waves mixing. In this project, more than 20 dB reductions is seen in the spectral re-growth caused by the SOA. Amplifier non-linearity becomes more severe with two strong input channels leading to inter-channel distortion which can completely mask a third adjacent channel. The simulations detailed above were performed utilizing optimum settings for the variable gain, phase and delay components in the error correction loop of the feed forward and Predistortion systems and hence represent the ideal situation of a perfect feed-forward and Predistortion system. Therefore it should be consider that complexity of circuit will increase due to amplitude, phase and delay mismatches in practical design. Also it has describe the compatibility of Software Defined Radio with Hybrid Fibre Radio with simulation model of wired optical networks to be used for future research investigation, based on the star and ring topologies for different modulation schemes, and providing the performance for these configurations.

Doctor of Philosophy / Department of Electrical and Computer Engineering / William B. Kuhn / Design challenges and solution methods for Watt-level UHF CMOS power amplifiers are presented. Using the methods, a fully-integrated UHF (400MHz) CMOS power amplifier (PA) with more than 1-Watt output is demonstrated for the first time in Silicon on Sapphire (SOS) process. The design techniques are extended for a two-stage five-chip 5-Watt CMOS PA. In the 1-Watt PA, a differential stacked PMOS structure with floating-bias and a 1:3 turns-ratio output transformer are chosen to overcome low breakdown voltage (Vbk) of CMOS and chip area consumption issues at UHF frequencies. The high Q on-chip transformer on sapphire substrate enables the differential PA to drive a single-ended antenna effectively at 400 MHz. The PA is designed for a surface-to-orbit proximity link microtransceiver, used on Mars exploration rovers, aerobots and small networked landers. In a standard package the PA delivers 30 dBm output with 27 % PAE. No performance degradation was observed in continuous wave (CW) operation with various output terminations and the PA was tested to 136 % of its nominal 3.3 V supply without failure. Stability analysis and measurements show that the PA is stable in normal operation. It is also shown that the PA is thermally reliable. In the microtransceiver circuits, the PA works in conjunction with transmit/receive (TR) switch to allow nearly the full 1-Watt to reach the antenna. The 1-Watt PA design is also leveraged to demonstrate a power-combined two-stage five-chip PA. The 1-Watt PA’s output balun is modified for the four-transformer combining. Four identical chips are wire-bonded in the output stage and the fifth identical chip is added as a drive-amplifier. Despite low efficiency due to damaged bias circuits, the PA provides 5-Watt output power (37 dBm) at 480 MHz with 17 % PAE with 17 dB gain. The PA layout is carried out considering full integration on a 7×10mm2 die. It will be the highest output CMOS PA ever reported once the full integration is implemented. The research contributes to state of the art by developing design-techniques for a TR switch and PAs on SOS process. The resonant TR switch technique is applied to a full transceiver and the multi turns-ratio on-chip transformer is used in PA’s output matching network for the first time. The PA design is also extended to the 5-Watt PA, demonstrating the highest output power in CMOS process.

Master of Science / Department of Physics / Brian R. Washburn / Rare-earth doped optical fibers can be used to make optical amplifiers in the near infrared with large optical gain in an all fiber based system. Indeed, erbium doped fibers made gain possible within the 1532 to 1560 nm band which makes long span fiber optical communication systems a possibility. Erbium doped fibers have also been used to make narrow linewidth or mode-locked lasers. Other rare-earth doped fibers can be used for amplifiers in other near-infrared spectral regions. Recently, fiber amplifier technology has been pushed to produce watt level outputs for high power applications such as laser machining. These high power amplifiers make new experiments in ultrafast fiber optics a possibility. This report reviews the current literature on Watt-class continuous wave erbium doped amplifiers and discussed our attempt to develop a high power Yb/Er amplifier. After the design of the cladding pump in 1999, the world’s first single mode fiber laser with a power greater than 100 Watts of the continuous wave light was introduced. After 2002 there was a huge spike in the output powers (up to 2 kW) of lasers based on rare-earth doped fibers. Our own work involved developing a 10 W amplifier at 1532 nm and 1560 nm. A high power amplifier was made by seeding a dual-clad Yb/Er co-doped fiber pumped at 925 nm using a lower power erbium doped fiber amplifier. We will discuss the design and construction of the amplifier, including the technical difficulties for making such an amplifier.

Neste trabalho investiga-se, inicialmente, o comportamento de um amplificador klystron de múltiplas cavidades segundo uma análise a pequenos sinais linear considerando o efeito de carga espacial para, na seqüência, apresentar uma análise do dispositivo utilizando um modelo não-linear a grandes sinais. Na primeira investigação apresenta-se, a partir da teoria dos modos normais, expressões que descrevem o balanço de potência complexo em uma cavidade excitada por um feixe de elétrons. Na seqüência, utiliza-se um modelo linearizado a pequenos sinais para desenvolver uma expressão para a densidade de corrente de convecção ao longo do tubo de deriva acoplado a múltiplas cavidades reentrantes, em função do campo elétrico produzido nos gaps de interação das cavidades. Estas expressões formam a base para a determinação do ganho de voltagem e de ganho de potência de um amplificador klystron de múltiplas cavidades, além da determinação de uma expressão para a largura de banda, sob a hipótese de cavidades idênticas e igualmente espaçadas. O código desenvolvido é validado utilizando-se os parâmetros de um amplificador klystron de 4 cavidades, com corrente d.c. de 525 mA, voltagem d.c. de 6 kV e freqüência de 1,849 MHz, quando se obteve um ganho de 70 dB. Na análise a grandes sinais, o modelo matemático utiliza o formalismo lagrangiano para resolver a dinâmica das partículas, descritas conforme o modelo de discos com raio finito, em uma análise unidimensional, considerando os efeitos não-lineares devido aos campos de carga espacial. O código é validado usando os dados de um amplificador klystron comercial Varian. Dentre outros, os gráficos da velocidade e da densidade do feixe de elétrons, da corrente harmônica, do ganho por cavidade, da conversão AM/AM, da compressão de ganho e da energia do sistema são mostrados e discutidos. Além disso, apresentou-se também um método para a determinação da freqüência de ressonância 0 f , para o fator de qualidade Q e para a razão (R Q) em cavidades cilíndricas reentrantes, de relevância para o projeto de amplificadores klystron de múltiplas cavidades, utilizando a técnica do casamento de admitância do gap de interação entre a cavidade e o tubo de deriva. Um dos resultados mais significativos é o da corrente harmônica fundamental, que resultou 60% maior do que a corrente d.c. considerando um dispositivo com 4 cavidades. / This work investigates, initially, a klystron amplifier with multiple cavities using a small signal analysis considering the space charge effects for, in sequence, provide an analysis of the device using a model for large signals. In the first investigation is presented, from the normal modes theory according to J. Slater, expressions that describe the complex balance of power in a cavity excited by an electron beam. Subsequently, it uses a linearized model for small signals to develop an expression for the convection current density along the drift tube coupled to multiple reentrant cavities, depending on the electric field produced in the interaction gaps of the cavities. These expressions form the basis for determining the voltage gain and power gain of an amplifier klystron to multiple cavities, and determination of an expression for the bandwidth, under the hypothesis of identical and equally spaced cavities. The developed code is validated using the parameters of a klystron amplifier, four cavities, with dc current 525 mA, dc voltage of 6 kV, and frequency of 1.849 GHz, when it obtained a gain of 70 dB. In the large signal analysis, the mathematical model uses the lagrangian formalism to solve the dynamics of particles, described as the model disk with finite radius in a one-dimensional analysis, considering the nonlinear effects due to space charge fields. The code is validated using data from a commercial Varian klystron amplifier of 1.848 GHz. Among others, the graphs of velocity and density of the electron beam, the harmonic current, the gain per cavity, the conversion AM/AM compression gain and energy of the system are shown and discussed. Moreover, it is presented a method for determining the resonant frequency 0 f , for the quality factor Q and the (R Q) at reentrant cylindrical cavities, of relevance for the design of a klystron amplifier of multiple cavities, using the admittance matching technique in the gap of interaction between the cavity and drift tube. One of the more significant is the fundamental harmonic current, which resulted 60% higher than the dc current considering a device with four cavities.

Neste trabalho investiga-se, inicialmente, o comportamento de um amplificador klystron de múltiplas cavidades segundo uma análise a pequenos sinais linear considerando o efeito de carga espacial para, na seqüência, apresentar uma análise do dispositivo utilizando um modelo não-linear a grandes sinais. Na primeira investigação apresenta-se, a partir da teoria dos modos normais, expressões que descrevem o balanço de potência complexo em uma cavidade excitada por um feixe de elétrons. Na seqüência, utiliza-se um modelo linearizado a pequenos sinais para desenvolver uma expressão para a densidade de corrente de convecção ao longo do tubo de deriva acoplado a múltiplas cavidades reentrantes, em função do campo elétrico produzido nos gaps de interação das cavidades. Estas expressões formam a base para a determinação do ganho de voltagem e de ganho de potência de um amplificador klystron de múltiplas cavidades, além da determinação de uma expressão para a largura de banda, sob a hipótese de cavidades idênticas e igualmente espaçadas. O código desenvolvido é validado utilizando-se os parâmetros de um amplificador klystron de 4 cavidades, com corrente d.c. de 525 mA, voltagem d.c. de 6 kV e freqüência de 1,849 MHz, quando se obteve um ganho de 70 dB. Na análise a grandes sinais, o modelo matemático utiliza o formalismo lagrangiano para resolver a dinâmica das partículas, descritas conforme o modelo de discos com raio finito, em uma análise unidimensional, considerando os efeitos não-lineares devido aos campos de carga espacial. O código é validado usando os dados de um amplificador klystron comercial Varian. Dentre outros, os gráficos da velocidade e da densidade do feixe de elétrons, da corrente harmônica, do ganho por cavidade, da conversão AM/AM, da compressão de ganho e da energia do sistema são mostrados e discutidos. Além disso, apresentou-se também um método para a determinação da freqüência de ressonância 0 f , para o fator de qualidade Q e para a razão (R Q) em cavidades cilíndricas reentrantes, de relevância para o projeto de amplificadores klystron de múltiplas cavidades, utilizando a técnica do casamento de admitância do gap de interação entre a cavidade e o tubo de deriva. Um dos resultados mais significativos é o da corrente harmônica fundamental, que resultou 60% maior do que a corrente d.c. considerando um dispositivo com 4 cavidades. / This work investigates, initially, a klystron amplifier with multiple cavities using a small signal analysis considering the space charge effects for, in sequence, provide an analysis of the device using a model for large signals. In the first investigation is presented, from the normal modes theory according to J. Slater, expressions that describe the complex balance of power in a cavity excited by an electron beam. Subsequently, it uses a linearized model for small signals to develop an expression for the convection current density along the drift tube coupled to multiple reentrant cavities, depending on the electric field produced in the interaction gaps of the cavities. These expressions form the basis for determining the voltage gain and power gain of an amplifier klystron to multiple cavities, and determination of an expression for the bandwidth, under the hypothesis of identical and equally spaced cavities. The developed code is validated using the parameters of a klystron amplifier, four cavities, with dc current 525 mA, dc voltage of 6 kV, and frequency of 1.849 GHz, when it obtained a gain of 70 dB. In the large signal analysis, the mathematical model uses the lagrangian formalism to solve the dynamics of particles, described as the model disk with finite radius in a one-dimensional analysis, considering the nonlinear effects due to space charge fields. The code is validated using data from a commercial Varian klystron amplifier of 1.848 GHz. Among others, the graphs of velocity and density of the electron beam, the harmonic current, the gain per cavity, the conversion AM/AM compression gain and energy of the system are shown and discussed. Moreover, it is presented a method for determining the resonant frequency 0 f , for the quality factor Q and the (R Q) at reentrant cylindrical cavities, of relevance for the design of a klystron amplifier of multiple cavities, using the admittance matching technique in the gap of interaction between the cavity and drift tube. One of the more significant is the fundamental harmonic current, which resulted 60% higher than the dc current considering a device with four cavities.

The erbium-based optical amplifier (EDFA) plays a vital role in the global fibre-optic telecommunication network. However, there are two main issues with current EDFAs, their bulky size means that they cannot be integrated into silicon-based photonic devices, and they need high pump power to produce optical gain. Here, a potential organo-erbium gain system has been invented, which could be operated under a low pump power and integrated onto a silicon-based device. The fully-fluorinated organic erbium complex [Er(ftpip)3] was mixed with a fully-fluorinated organic zinc complex [Zn(F-BTZ)2], acting as a chromophore over the visible range. The composite provides extraordinary sensitisation from the Zn(F-BTZ)2 to Er(ftpip)3 over a broad-visible band, which is compatible with high power LEDs, whilst the erbium ions have a new record of IR emission lifetime of ~ 0.8 ms (quantum yield = ~ 7%). The integrated sensitisation is ~ 104 times that of the intrinsic excitation into erbium. This system has been integrated into an organic light emitting diodes (OLEDs) demonstrating that the energy transfer is dominated by triplet states of the Zn(F-BTZ)2. This is used for explaining the photoluminescence saturation and large pump-rate, with the composite being excited by a low power diode laser on the chromophore units. This composite-system was used to fabricate a slab waveguide, in which an relative gain of 3.4 dB/cm was achieved when excited by a diode laser with 3 mW. A microscopic-optic setup was designed to measure IR line strengths of erbium ions in crystals of complexes, which were included in theoretical calculation to obtain accurate quantum yield for IR emission of erbium ions. The inclusion of IR line strengths measured from crystals is found to be crucial for Judd-Ofelt parameterisation on organic erbium complexes. It was demonstrated that fluorination could increase the line strengths of hypersensitive transitions and IR transition for 1.5 μm band.