System architecture of an all-digital GHz transmitter using pulse-width/position-modulation for switching-mode PAs

This paper presents a novel concept for direct-pulse-width/position-modulation (PWPM) in an all-digital transmitter by using a parallel baseband PWPM and high speed digital up-conversion. By parallel calculation and subsequent serialization of the digital PWPM signal carrier frequencies above 1 GHz become feasible. PWPM enables the usage of highly efficient switching-mode power amplifiers (SMPA) and direct control of the output power. Because PWPM modulator can be completely implemented in the digital, time discrete domain, all analogue baseband blocks can be dropped and replaced by reconfigurable digital blocks. The only remaining mixed-signal and analogue blocks are the multiplexer and the power amplifier. Requirements on the digital and mixed-signal blocks are discussed. Feasibility of the concept is demonstrated by system and circuit simulations showing the possibility of using digital PWPM in wireless applications.

[1]  Marian K. Kazimierczuk,et al.  Power losses and efficiency of class-E power amplifier at any duty ratio , 2004, IEEE Transactions on Circuits and Systems I: Regular Papers.

[2]  P. Asbeck,et al.  Digital generation of RF signals for wireless communications with band-pass delta-sigma modulation , 2001, 2001 IEEE MTT-S International Microwave Sympsoium Digest (Cat. No.01CH37157).

[3]  M. B. Sandler,et al.  Power digital to analogue conversion using pulse width modulation and digital signal processing , 1993 .

[4]  P. Asbeck,et al.  Generation of RF pulsewidth modulated microwave signals using delta-sigma modulation , 2002, 2002 IEEE MTT-S International Microwave Symposium Digest (Cat. No.02CH37278).

[5]  R. Farrell,et al.  Using high pass sigma-delta modulation for Class-S power amplifiers , 2007, 2007 18th European Conference on Circuit Theory and Design.

[6]  Joachim Holtz.  Pulsewidth modulation-a survey , 1992, IEEE Trans. Ind. Electron..

[7]  Peter M. Asbeck,et al.  Transmitter architecture using digital generation of RF signals , 2003, Radio and Wireless Conference, 2003. RAWCON '03. Proceedings.

[8]  Fadhel M. Ghannouchi,et al.  A Novel Architecture of Delta-Sigma Modulator Enabling All-Digital Multiband Multistandard RF Transmitters Design , 2008, IEEE Transactions on Circuits and Systems II: Express Briefs.