Jitter Limitations on Multi-Carrier Modulation

A feasibility study is made of an OFDM system based on analog multipliers and integrate-and-dump blocks, targeted at Gb/s copper interconnects. The effective amplitude variation of the integrator output caused by jitter is explained in an intuitive way by introducing correlation plots. For a given rms jitter and error rate, high frequency carriers allow for less modulation depth than low frequency carriers. A jitter limit on the total system bit rate is calculated, which is a function of rms jitter, bandwidth, and specified system symbol error rate. It is concluded that, because of the high sensitivity to timing errors inherent in OFDM, traditional PAM systems with equal bandwidth and error rate are more feasible

Towards On-Chip Self-Referenced Frequency-Comb Sources Based on Semiconductor Mode-Locked Lasers.

Miniaturization of frequency-comb sources could open a host of potential applications in spectroscopy, biomedical monitoring, astronomy, microwave signal generation, and distribution of precise time or frequency across networks. This review article places emphasis on an architecture with a semiconductor mode-locked laser at the heart of the system and subsequent supercontinuum generation and carrier-envelope offset detection and stabilization in nonlinear integrated optics

Post Conversion Correction of Non-Linear Mismatches for Time Interleaved Analog-to-Digital Converters

Time Interleaved Analog-to-Digital Converters (TI-ADCs) utilize an architecture which enables conversion rates well beyond the capabilities of a single converter while preserving most or all of the other performance characteristics of the converters on which said architecture is based. Most of the approaches discussed here are independent of architecture; some solutions take advantage of specific architectures. Chapter 1 provides the problem formulation and reviews the errors found in ADCs as well as a brief literature review of available TI-ADC error correction solutions. Chapter 2 presents the methods and materials used in implementation as well as extend the state of the art for post conversion correction. Chapter 3 presents the simulation results of this work and Chapter 4 concludes the work. The contribution of this research is three fold: A new behavioral model was developed in SimulinkTM and MATLABTM to model and test linear and nonlinear mismatch errors emulating the performance data of actual converters. The details of this model are presented as well as the results of cumulant statistical calculations of the mismatch errors which is followed by the detailed explanation and performance evaluation of the extension developed in this research effort. Leading post conversion correction methods are presented and an extension with derivations is presented. It is shown that the data converter subsystem architecture developed is capable of realizing better performance of those currently reported in the literature while having a more efficient implementation

A Carrierless Amplitude Phase (CAP) Modulation Format: Perspective and Prospect in Optical Transmission System

The explosive demand of broadband services nowadays requires data communication systems to have intensive capacity which subsequently increases the need for higher data rate as well. Although implementation of multiple wavelengths channels can be used (e.g. 4 × 25.8 Gb/s for 100 Gb/s connection) for such desired system, it usually leads to cost increment issue which is caused by employment of multiple optical components. Therefore, implementation of advanced modulation format using a single wavelength channel has become a preference to increase spectral efficiency by increasing the data rate for a given transmission system bandwidth. Conventional advanced modulation format however, involves a degree of complexity and costly transmission system. Hence, carrierless amplitude phase (CAP) modulation format has emerged as a promising advanced modulation format candidate due to spectral efficiency improvement ability with reduction of optical transceiver complexity and cost. The intriguing properties of CAP modulation format are reviewed as an attractive prospect in optical transmission system applications

On the Implementation of Carrierless Amplitude and Phase Modulation in Visible Light Communication

OAPA Carrierless amplitude and phase modulation (CAP) is one of the spectrally efficient schemes that has been proposed to tackle the limited modulation bandwidth challenge in visible light communication (VLC). The VLC technology leverages existing lighting fixtures to provide wireless data communication, which makes it attractive for many applications. However, the commercially available white LEDs that are predominantly employed in VLC offer low modulation bandwidths that limit the achievable data rate. Thus, CAP modulation is employed to improve achievable data rate, primarily due to its implementation simplicity and high spectral efficiency. The CAP scheme also has a special feature in that it can be implemented as a single band or a multiband scheme which provides design flexibility. This paper presents an in-depth study of the implementation of CAP in LED-based VLC systems, highlighting the unique features that make it specially suited for VLC applications. Furthermore, a comprehensive investigation is carried out regarding the design parameters of the CAP modulation transceiver, its benefits and techniques to mitigate the challenges of CAP-based VLC systems

The Design of a CD Transport for Audio Applications

The project to design a CD transport (CD player) in conjunction with Perreaux Industries came about from the need for a source component in their Silhouette series of products. This project describes the design a high quality CD player, at a low price, to compliment Perreaux's Silhouette series. A CD drive is selected over a proprietary optical pickup due to the former's low cost and the standardisation of the interface. The control circuitry includes a micro controller and discrete logic to provide the correct data and clock signals to the SPDIF transmitter and DAC circuits. These two circuits provided a high quality analogue output, and facilitate an upgrade path by connecting the SPDIF output to an external DAC. After three board iterations, a final production ready revision was achieved. The design includes a high quality toroidal transformer, low jitter crystal oscillator, and a very high quality SPDIF pulse transformer output. The design also allows a remote input to control the player, and an optional digital cable via an RJ45 connector to provide synchronisation with a future design of the SXD2 DAC module, or to transmit SPDIF to a remote location. The specifications of the final design were higher than expectations. The digital output boasts equal or superior performance to competitive products in the same price range, with the analogue output attaining exceptionally high performance