Title :
Asynchronous modulator for linearization and switch-mode RF power amplifier applications
Author :
Johnson, T. ; Mekechuk, K. ; Kelly, D. ; Lu, J.
Author_Institution :
PWRF Inc., Austin, TX, USA
Abstract :
An implementation of an asynchronous modulator which encodes a modulated RF signal into a two level pulse train is described. The modulator is designed for RF switch mode amplifier applications and feedback linearization using conventional linear power amplifiers. The modulator is implemented in 0.18 mum SiGe BiCMOS and operates over a frequency range from 750 MHz to 2.2 GHz. The design includes the implementation of a fourth order complex bandpass filter and an encoder to synthesize a binary pulse train with asynchronous zero crossings. Experimental results are shown for a power amplifier module where the modulator is configured in a feedback loop linearizing a Doherty power amplifier while processing a three carrier WCDMA input signal.
Keywords :
BiCMOS integrated circuits; Ge-Si alloys; UHF integrated circuits; UHF power amplifiers; modulators; BiCMOS; Doherty power amplifier; SiGe; WCDMA input signal; asynchronous modulator; asynchronous zero crossing; bandpass filter; binary level pulse train; feedback loop linearization; frequency 750 MHz to 2.2 GHz; level pulse train; linear power amplifier; size 0.18 mum; switch-mode RF power amplifier application; BiCMOS integrated circuits; Feedback; Germanium silicon alloys; Power amplifiers; Pulse amplifiers; Pulse modulation; Radio frequency; Radiofrequency amplifiers; Silicon germanium; Switches; feedback amplifiers; microwave power amplifiers; sigma-delta modulation; switching amplifiers;
Conference_Titel :
Radio Frequency Integrated Circuits Symposium, 2009. RFIC 2009. IEEE
Conference_Location :
Boston, MA
Print_ISBN :
978-1-4244-3377-3
Electronic_ISBN :
1529-2517
DOI :
10.1109/RFIC.2009.5135518
