Pruned Tree Sigma-Delta Modulation for SA-CD

In chapter ten, the Pruned Tree sigma-delta modulation algorithm for Super Audio CD (SA-CD) is presented. The algorithm has a better compatibility with Super Audio CD, because it generates bitstreams that result in a high lossless data compression gain. This is achieved by adding a cost function to the look-ahead filter that measures the predictability of the output signal. This addition results in an output bitstream that is of a high signal quality, but that is also very predictable, such that the amount of required disc storage space after lossless data compression reduces. This reduction of the required storage space is of great importance, since it solves potential playback duration issues. The addition of the prediction cost function has only a minimal impact on the SNR, while the distortion and the noise-modulation performance of the converter are strongly reduced, resulting in the ideal sigma-delta converter for high-end audio applications.</p

Basics of Sigma-Delta Modulation

This chapter provides a basic introduction to sigma-delta modulation in general. It first discusses the use of sigma-delta modulation for analog-to-digital, digital-to-digital, and digital-to-analog conversion, after which the most popular sigma-delta structures are presented. A procedure for basic linear modeling of sigma-delta modulators is presented and it’s shortcomings are demonstrated. Because of the potentially large discrepancy between the by the model predicted results and the actual obtained results, time domain simulations are used in this book. Finally, a number of often used sigma-delta performance indicators are presented to set a basis for the comparison of different sigma-delta modulator realizations

Comparison of Look-Ahead SDM Techniques

All of the previously discussed look-ahead techniques are compared in chapter eleven. The outcome of this comparison is that the normal Pruned Tree sigma-delta modulation algorithm is the best choice if the converter is not intended for audio applications, since it offers the highest SNR, very good linearity, and the largest stability at the minimal computational cost. In the case of a high-end application for Super Audio CD, the Pruned Tree sigma-delta modulation algorithm for SA-CD is the best choice because of the constant in-band noise-floor and the higher compression gains that are obtained on the output bitstream.</p

An integral shannon-based view on smart front-ends (invited) An Integral Shannon-Based View on Smart Front-Ends

Abstract-This paper describes how trends in information society, communication technology, microwave technology, and IC-design technology, ask for a different view on front-ends. The communication channel will be described from a high level, as one &apos;Shannon channel&apos;, comprising a chain of cascaded sub channels. Trends influencing each sub channel will be addressed. From that, we will argue that an integral approach to the design of the communication chain will be a prerequisite for the design of future front-ends. Moreover, the design of the front-end will become dominated by the IC part of the chain, rather than by the transmission channel, which will lead to &apos;conversion-driven&apos; rather than &apos;transmission-channel driven&apos; analog front-ends. Finally, it will be shown that future converters will have to be smart. Although applied to wireless, the conclusions are generic and as such can be applied to wired communication channels too

Look-Ahead Sigma-Delta Modulation

The generic noise-shaping quantizer model from chapter four is modified to support look-ahead, and a hypothetical sigma-delta modulator with look-ahead capability is derived. From here the main principles of look-ahead are explored, including linear modeling of a look-ahead modulator, and an overview of expected benefits and disadvantages of a look-ahead sigma-delta modulator. Although only with an infinite amount of look-ahead the global optimal encoding solution can be found, it is concluded that already with a limited amount of look-ahead an improvement in the signal conversion performance can be obtained. The benefits of look-ahead, primarily an increase of the stability and a reduction of the distortion, are the biggest in the case of a 1-bit converter, since here the quantizer is severely non-linear. Therefore, in the remaining chapters the focus will be primarily on 1-bit converters. The operation of the full look-ahead algorithm, an algorithm that can be found in open literate and that performs an exhaustive search for the best solution within the look-ahead depth, is reviewed. With these insights the feasibility of an analog-to-digital converter with look-ahead is investigated, and it is concluded that the feasibility is low. It is found that in the case of a digital-to-digital converter, in principle, look-ahead can be implemented without major difficulties, but that the traditional full look-ahead approach is not computationally efficient.</p