Efficiency enhancement and linearity trade-offs for cascode vs. common-emitter SiGe power amplifiers in WiMAX polar transmitters

Yan Li, Jerry Lopez, Donald Y.C. Lie, Kevin Chen, Stanley Wu, Tzu Yi Yang

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

9 Scopus citations

Abstract

In this paper, a monolithic RF cascode SiGe power amplifier (PA) design capable of enhancing its power-added efficiency (PAE) is demonstrated. Four RF switches are adopted at the bases of the common-emitter transistors, which can be turned on/off in response to the desired output power. Simulations show that by utilizing device size variation, our cascode PA achieves higher gain and PAE compared to conventional fixed-size cascode PA in the low power region; in addition, it also provides more output power and higher average PAE than single-stage common-emitter PAs. We also studied and compared the linearity performance of our cascode PAs vs. single-stage common-emitter PAs in a RF polar TX using an envelope tracking (ET) technique. We found that even through self-biasing for the common-base device can improve the output distortion of cascode PAs, a single-stage common-emitter SiGe PA designed for comparison is still considerably more linear than cascode PAs. Therefore, more careful system linearization design will be critical when the cascode PAs are adopted in RF polar transmitters (TXs), especially for broadband wireless applications such as mobile WiMAX studied here.

Original languageEnglish
Title of host publicationISCAS 2010 - 2010 IEEE International Symposium on Circuits and Systems
Subtitle of host publicationNano-Bio Circuit Fabrics and Systems
Pages1915-1918
Number of pages4
DOIs
StatePublished - 2010
Event2010 IEEE International Symposium on Circuits and Systems: Nano-Bio Circuit Fabrics and Systems, ISCAS 2010 - Paris, France
Duration: May 30 2010Jun 2 2010

Publication series

NameISCAS 2010 - 2010 IEEE International Symposium on Circuits and Systems: Nano-Bio Circuit Fabrics and Systems

Conference

Conference2010 IEEE International Symposium on Circuits and Systems: Nano-Bio Circuit Fabrics and Systems, ISCAS 2010
CountryFrance
CityParis
Period05/30/1006/2/10

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