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Báo cáo hóa học: " Research Article Description of a 2-Bit Adaptive Sigma-Delta Modulation System with Minimized Idle Tones"

Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: Research Article Description of a 2-Bit Adaptive Sigma-Delta Modulation System with Minimized Idle Tones | Hindawi Publishing Corporation EURASIP Journal on Advances in Signal Processing Volume 2008 Article ID 426502 6 pages doi 10.1155 2008 426502 Research Article Description of a 2-Bit Adaptive Sigma-Delta Modulation System with Minimized Idle Tones E. A. Prosalentis and G. S. Tombras Laboratory of Electronics Department of Physics University of Athens Panepistimiopolis 157 84 Athens Greece Correspondence should be addressed to G. S. Tombras gtombras@phys.uoa.gr Received 3 June 2007 Revised 24 September 2007 Accepted 28 October 2007 Recommended by Jiri Jan A 2-bit adaptive sigma delta modulation system that inherently eliminates the idle tones present in conventional and other adaptive sigma delta systems is described. The system incorporates both memory and look-ahead instantaneous step-size estimations and as shown by computer simulation results apart from eliminating the unwanted idle tones despite dithering it offers improved SNR performance and extended dynamic range. Copyright 2008 E. A. Prosalentis and G. S. Tombras. This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited. 1. INTRODUCTION Sigma-delta modulation SDM is extensively used in various applications due to its high resolution and relatively simple analog implementation. In a simplifying SDM system analysis the effect of the corresponding 1-bit quantization is widely approximated by an additive white noise model although generally the quantization error is not white. Indeed considering quantization of DC input signals the resulting waveform can be periodic by revealing the so-called idle tones or a noise pattern. This tonal behavior may cause problems when SDM is particularly used in audio applications. In this respect various dithering techniques have successfully employed in whitening the pattern noise with different amounts of dynamic range .