A 250 MHz to 8 GHz GaAs pHEMT IQ Modulator

Kiyoyuki IHARA  

Publication
IEICE TRANSACTIONS on Electronics   Vol.E96-C   No.2   pp.245-250
Publication Date: 2013/02/01
Online ISSN: 1745-1353
DOI: 10.1587/transele.E96.C.245
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Microwaves, Millimeter-Waves
Keyword: 
IQ modulator,  EVM,  direct conversion,  GaAs,  pHEMT,  ACPR,  temperature drift,  distortion,  

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Summary: 
The author developed a wideband precise I/Q modulator using GaAs pHEMT technology. In this technology, pHEMT has 0.22 µm metallurgical gate length and ft=51 GHz at Vds=5V. With the careful design of the wideband phase shifter, this IQ modulator achieved a large wideband frequency range of 250 MHz to 8 GHz and good EVM performance after calibration. For overall frequency range, low distortion performance is obtained, where third order intermodulation is less than -42 dBc. Also the ACPR at 2.2 GHz for W-CDMA application is less than -74 dBc.