In cellular and personal communications services (PCS) systems based on code division multiple access (CDMA), a pilot signal is used on the forward link for synchronization, coherent detection, soft handoff, maintaining orthogonality between base stations, and, in the future, position location. It is critical that the percentage of power allocated to the pilot signal transmitted by each base station be fixed properly to ensure the ability of the CDMA network to support subscriber demand. This thesis reports on the design and implementation of a prototype receiver for measuring pilot signals in CDMA PCS systems. Since the pseudonoise (PN) signal of the pilot channel is a priori information, the receiver searches for pilot signals by digitally correlating the received signal with this known, locally generated pilot signal. By systematically changing the phase of this locally generated pilot signal, the receiver scans the received signal to identify all possible signs of pilot signal activity. Large values of correlation indicate the presence of a pilot signal at the particular phase of the locally generated pilot signal. The receiver can also detect multipath components of the pilot signal transmitted from a given base station. One issue associated with this receiver is its ability to keep the signal power within the dynamic range of the analog-to-digital (A/D) converter at its input. This necessitated the design of an automatic gain control (AGC) mechanism, which is digitally implemented in this receiver. Simulation studies were undertaken to assist in the design and implementation of the pilot signal scanning receiver. These simulations were used to quantify how various non-idealities related to the radio frequency (RF) front-end and A/D converter adversely affect the ability of the digital signal processing algorithms to detect and measure pilot signals. Because the period of the pilot signal is relatively long, methods were developed to keep the receiver's update period as small as possible without compromising its detection ability. Furthermore, the high sampling rate required strains the ability of the digital logic to produce outputs at a rate commensurate with real-time operation. This thesis presents techniques that allow the pilot signal scanning receiver to achieve real-time operation. These techniques involve the judicious use of partial correlations and windowing the received signal to decrease the transfer rate from the A/D converter to the digital signal processor. This thesis provides a comprehensive discussion of these and other issues associated with the actual hardware implementation of the pilot signal scanning receiver. / Master of Science

Visando atender a massificação das tecnologias da informação e comunicação (TIC) por meio de um aproveitamento mais eficiente da infra-estrutura de fibras ópticas, as redes ópticas DWDM vem passando por significativa evolução de capacidade, com base no uso de formatos de modulação avançados, para canais operando em taxas de 100 Gb/s e superiores, bem como no emprego de topologias dinâmicas e reconfiguráveis. Estas redes ópticas de nova geração impõe novos requisitos de desempenho aos amplificadores ópticos. Especificamente, as características dinâmicas da rede tornam obrigatório o uso de esquemas de controle que assegurem estrita planicidade espectral de ganho enquanto o emprego de formatos de modulação avançados e de alta ordem requer margens mais estreitas em termos da relação sinal-ruído aceitável para detecção dos sinais recebidos. Neste contexto, esta tese propõe e avalia experimentalmente uma topologia de amplificação óptica híbrida Raman/EDFA, introduzindo um novo esquema de controle automático de ganho e apresentando desempenho superior aos amplificadores atualmente usados em redes DWDM reconfiguráveis. O amplificador óptico híbrido desenvolvido baseia-se em um estágio Raman distribuído contra-propagante, com excelente desempenho de figura de ruído (porém com baixa eficiência de conversão de bombeio em amplificação - PCE) seguido de um estágio EDFA, que assegura alta potência de saída, devido a sua elevada PCE. Ganho espectral plano foi obtido por meio de uma técnica de controle automático de ganho inovadora, baseada na atuação paralela e independente de duas malhas de controle automático de ganho, uma primeira aplicada ao estágio de amplificação Raman visando ganho-alvo variável com baixa variação espectral, enquanto outra malha de controle de ganho visa fornecer ganho alvo fixo ao estágio EDFA, com alta potência de saída. / Seeking to support the massive deployment of information and communication technologies (ICTs) by means of a more efficient usage of the optical fiber infrastructure, DWDM optical networks have been undergoing a significant capacity evolution, by using advanced modulation formats for optical channels operating at data rates of 100 Gb/s and beyond, as well as by employing dynamic and reconfigurable network topologies. These new generation optical networks impose new performance benchmarks on the optical amplifiers. Specifically, the dynamic characteristics of the network make mandatory the deployment of control schemes which assure stringent optical gain spectral flatness while the usage of high-order advanced modulation formats translate into more strict margins of signal-to-noise ratios for the detected signals. In this context, this thesis proposes and experimentally evaluates an hybrid Raman/ EDFA optical amplifier topology, introducing a novel automatic gain control scheme and demonstrating improved performance over the optical amplifiers already in use in DWDM reconfigurable networks. The developed hybrid optical amplifier is based on a distributed counter-propagating Raman stage, displaying excellent noise figure performance (albeit presenting low conversion efficiency - PCE) followed by an EDFA stage, which assures high output power, due to its high PCE. Flat spectral gain was achieved by means of a novel gain control technique, based on the parallel and independently acting of two control schemes, the first applied over the Raman amplifying stage, aiming at a variable target gain and low spectral gain ripple, while the other seeks to attain a fixed target gain at the EDFA, assuring a high output power.

Abstract In this thesis, we use a high power 1550 nm DFB laser and a Ti:LiNbO3 Mach-Zehnder modulator to construct an externally modulated trensmitter for CATV lightwave system. We use two methods to reduce the problem caused by stimulated Brillouin scattering (SBS) effect in externally modulated AM video system by using high-frequency phase modulation and low-frequency dithering techniques. In this experiment, the SBS threshold can be increased by 6 dB. We also design a automatic gain control (AGC) circuit with a 10 dB dynamic range in our transmitter. After addition with a home-made predistortion linearized circuit, the system performance of this transmitter in a 20 km single-mode fiber link carrying 60 NTSC channels can be achieved with a CNR¡Ù46~52 dB¡BCSO¡Ø-68~-73 dBc¡BCTB¡Ø-59~-63 dBc. As the number of channels increased from 60 to 80, we can obtain CNR¡Ù46~51 dB, CSO¡Ø-65.5~-71 dBc, and CTB¡Ø-55~-60.4 dBc. According to preceding description, we know that our trensmitter can carry 60 ~ 80 NTSC channels.

Visando atender a massificação das tecnologias da informação e comunicação (TIC) por meio de um aproveitamento mais eficiente da infra-estrutura de fibras ópticas, as redes ópticas DWDM vem passando por significativa evolução de capacidade, com base no uso de formatos de modulação avançados, para canais operando em taxas de 100 Gb/s e superiores, bem como no emprego de topologias dinâmicas e reconfiguráveis. Estas redes ópticas de nova geração impõe novos requisitos de desempenho aos amplificadores ópticos. Especificamente, as características dinâmicas da rede tornam obrigatório o uso de esquemas de controle que assegurem estrita planicidade espectral de ganho enquanto o emprego de formatos de modulação avançados e de alta ordem requer margens mais estreitas em termos da relação sinal-ruído aceitável para detecção dos sinais recebidos. Neste contexto, esta tese propõe e avalia experimentalmente uma topologia de amplificação óptica híbrida Raman/EDFA, introduzindo um novo esquema de controle automático de ganho e apresentando desempenho superior aos amplificadores atualmente usados em redes DWDM reconfiguráveis. O amplificador óptico híbrido desenvolvido baseia-se em um estágio Raman distribuído contra-propagante, com excelente desempenho de figura de ruído (porém com baixa eficiência de conversão de bombeio em amplificação - PCE) seguido de um estágio EDFA, que assegura alta potência de saída, devido a sua elevada PCE. Ganho espectral plano foi obtido por meio de uma técnica de controle automático de ganho inovadora, baseada na atuação paralela e independente de duas malhas de controle automático de ganho, uma primeira aplicada ao estágio de amplificação Raman visando ganho-alvo variável com baixa variação espectral, enquanto outra malha de controle de ganho visa fornecer ganho alvo fixo ao estágio EDFA, com alta potência de saída. / Seeking to support the massive deployment of information and communication technologies (ICTs) by means of a more efficient usage of the optical fiber infrastructure, DWDM optical networks have been undergoing a significant capacity evolution, by using advanced modulation formats for optical channels operating at data rates of 100 Gb/s and beyond, as well as by employing dynamic and reconfigurable network topologies. These new generation optical networks impose new performance benchmarks on the optical amplifiers. Specifically, the dynamic characteristics of the network make mandatory the deployment of control schemes which assure stringent optical gain spectral flatness while the usage of high-order advanced modulation formats translate into more strict margins of signal-to-noise ratios for the detected signals. In this context, this thesis proposes and experimentally evaluates an hybrid Raman/ EDFA optical amplifier topology, introducing a novel automatic gain control scheme and demonstrating improved performance over the optical amplifiers already in use in DWDM reconfigurable networks. The developed hybrid optical amplifier is based on a distributed counter-propagating Raman stage, displaying excellent noise figure performance (albeit presenting low conversion efficiency - PCE) followed by an EDFA stage, which assures high output power, due to its high PCE. Flat spectral gain was achieved by means of a novel gain control technique, based on the parallel and independently acting of two control schemes, the first applied over the Raman amplifying stage, aiming at a variable target gain and low spectral gain ripple, while the other seeks to attain a fixed target gain at the EDFA, assuring a high output power.

This work is focused on proposal of receiver with Integrated Antenna Tuner operating at 28 MHz. The design was primarily focused on simplicity and low power consumption. The receiver is adapted for SSB modulation. This work was realized for the transmission of audio signals. SSB modulation is far more efficient in terms of the radio spectrum used. First part of this thesis describes about the Antenna Tuner and block diagram of a receiver. Next parts are focused on proposal of individual blocks of the receiver, especially its most important parts. Finally, the overall evaluations of the design characteristics of SSB receivers with Integrated Antenna Tuner are discussed.

No description available.

This master's thesis deals with the design of a differential high-gain transimpedance amplifier in TSMC's 0.18 um mixed signal process that utilizes a DC photodiode current cancellation loop and a switching automatic gain control (AGC) with a bilinear gain curve. The amplifier is designed to satisfy the demands of Optical Coherence Tomography applications where the receiver is expected to measure the envelope power of an amplitude modulated sinusoidal optical signal that incorporates a large DC component. Methods of increasing dynamic range and gain linearity through the use of DC photodiode current cancellation and bilinear gain are explored. Effects of changing DC photodiode current on the overall system response is also demonstrated.

<p>This thesis presents the design of a broadband and high speed dc-coupled AGC amplifier for multi-level (4-PAM) signaling with a symbol rate of 1-GS/s ( 2-Gb/s ) . It is a high frequency analog design with several design challenges such as high -3 dB bandwidth ( greater than 500 MHz ) and highly linear gain while accommodating a large input swing range ( 120 mVp-p to 1800 mVp-p diff.) and delivering constant</p><p>differential output swing of 1700 mVp-p to 50-ohm off-chip loads at high speed. Moreover, the gain control circuit has been designed in analog domain. The amplifier incorporates both active and passive feedback in shunt-shunt topology in order to achieve wide bandwidth. This standalone chip has been implemented in AMS 0.35 micron CMOS process. The post layout eye-diagrams seem to be quite satisfactory.</p>

University of Macau / Faculty of Science and Technology / Department of Electrical and Electronics Engineering

This thesis presents the design of a broadband and high speed dc-coupled AGC amplifier for multi-level (4-PAM) signaling with a symbol rate of 1-GS/s ( 2-Gb/s ) . It is a high frequency analog design with several design challenges such as high -3 dB bandwidth ( greater than 500 MHz ) and highly linear gain while accommodating a large input swing range ( 120 mVp-p to 1800 mVp-p diff.) and delivering constant differential output swing of 1700 mVp-p to 50-ohm off-chip loads at high speed. Moreover, the gain control circuit has been designed in analog domain. The amplifier incorporates both active and passive feedback in shunt-shunt topology in order to achieve wide bandwidth. This standalone chip has been implemented in AMS 0.35 micron CMOS process. The post layout eye-diagrams seem to be quite satisfactory.