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báo cáo hóa học:" Research Article AD-PLL for WiMAX with Digitally-Regulated TDC and Glitch Correction Logic"

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 AD-PLL for WiMAX with Digitally-Regulated TDC and Glitch Correction Logic | Hindawi Publishing Corporation EURASIP Journal on Embedded Systems Volume 2010 Article ID 175764 8 pages doi 10.1155 2010 175764 Research Article AD-PLL for WiMAX with Digitally-Regulated TDC and Glitch Correction Logic Salvatore Levantino Marco Zanuso Paolo Madoglio Davide Tasca Carlo Samori and Andrea L. Lacaita Dipartimento di Elettronica e Informazione Politecnico di Milano Piazza L. da Vinci 32 20133 Milano Italy Correspondence should be addressed to Salvatore Levantino levantin@elet.polimi.it Received 30 June 2009 Accepted 23 September 2009 Academic Editor Sergio Saponara Copyright 2010 Salvatore Levantino et al. 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. This paper describes the design of an All-Digital Phase Locked Loop AD-PLL for wireless applications in the WiMAX 3.33.8 GHz bandwidth. The time digital converter TDC sets the in-band noise and it maybe responsible for the presence of spurious tones at the PLL output. The TDC is implemented as a delay-locked loop DLL to be insensitive to process spreads and it uses a lead-lag phase detector and a digital loop filter to further take advantage of the digital approach. The most important source of spurs is identified in the time skew between counter and TDC in the PLL. This mechanism gives rise to a glitch in the digital feedback signal and spurs in the output spectrum. A simple glitch-corrector logic is described that completely removes this effect thus allowing to meet the phase noise specifications. The AD-PLL has been designed in a 90 nm CMOS process. 1. Introduction In recent years the mixed-signal approach not only has pervaded many applications that once were exclusively a subject for the analog design but also has begun to play an important role also in radiofrequency RF front-ends. As a matter of fact the realization of software .