Delta

Sigma delta modulation has become a very useful and widely applied technique for high performance Analog-to-Digital (A/D) conversion of narrow band signals. Through the use of oversampling and negative feedback, the quantization errors of a coarse quantizer are suppressed in a narrow signal band in the output of the modulator. Bandpass sigma delta modulation is well suited for A/D conversion of narrow band signals modulated on a carrier, as occurs in communication systems such as AM/FM receivers and mobile phones. Due to the nonlinearity of the quantizer in the feedback loop, a sigma delta modulator may exhibit input signal dependent stability properties. The same combination of the nonlinearity and the feedback loop complicates the stability analysis. In Bandpass Sigma Delta Modulators, the describing function method is used to analyze the stability of the sigma delta modulator. The linear gain model commonly used for the quantizer fails to predict small signal stability properties and idle patterns accurately. In Bandpass Sigma Delta Modulators an improved model for the quantizer is introduced, extending the linear gain model with a phase shift. Analysis shows that the phase shift of a sampled quantizer is in fact a phase uncertainty. Stability analysis of sigma delta modulators using the extended model allows accurate prediction of idle patterns and calculation of small-signal stability boundaries for loop filter parameters. A simplified rule of thumb is derived and applied to bandpass sigma delta modulators. The stability properties have a considerable impact on the design of single-loop, one-bit, high-order continuous-time bandpass sigma delta modulators. The continuous-time bandpass loop filter structure should have sufficient degrees of freedom to implement the desired (small-signal stable) sigma delta modulator behavior. Bandpass Sigma Delta Modulators will be of interest to practicing engineers and researchers in the areas of mixed-signal and analog integrated circuit design.

This unique text presents the environmental history of the lowland delta of the rivers Rhine and Meuse. It is an ecological story of evolving human-environmental relations and how they cope with climate change and sea-level rise. The text offers a combination of in-depth ecology and environmental history. The synthesis presents a blueprint for future management and restoration, from progressive reclamation of land in the past, to adaptation of human needs to the forces of nature.

This unique book presents for the first time the current status of the Danube River Delta, the challenges facing it, and proposed strategies to solve it. One of the biggest challenges is the human effects on the Danube Delta Environment and its lakes that work as sinks for natural and anthropogenic environmental changes, the water management and water flow variability and under climatic conditions including the extreme temperature and precipitation events based on RCMs output and the impact of sedimentation processes on the evolution of the Danube Delta. The book also contains the impact of wind and solar energy on the Delta. The book also presents the integrated approach for sustainable development of the Delta including the structural dynamics of the local economy, the role of tourism activities, integrated waste management in the Danube Delta Biosphere Reserve, demographic dynamics in the Delta, and the population health state. Also, a unique chapter on the opportunities of content exploitation as Language Learning Experiences is applied to Danube Delta. The book will be of great scientific interest to help the graduate students, researchers, stakeholder professional engineers, policy planners, policymakers of three countries to implement their sustainable development plan.