New compact Ka-band CPW rat-race coupler using GaAs MMIC technology

Author

Chang, Chia-Lin ; Tseng, C.-H.

Author_Institution

Dept. of Electron. & Comput. Eng., Nat. Taiwan Univ. of Sci. & Technol., Taipei, Taiwan

Volume

49

Issue

19

fYear

2013

fDate

Sept. 12 2013

Firstpage

1227

Lastpage

1229

Abstract

A new compact Ka-band rat-race coupler (RRC) is proposed and fabricated in the 0.15-μm GaAs pHEMTs process. Since the developed RRC is implemented by asymmetrical coplanar-waveguide T-structures, it has a compact circuit footprint and a return-loss bandwidth similar to that of the conventional coupler. Besides, a short-circuited quarter-wave stub is attached into the ring of the RRC to flatten the output phase responses. The developed coupler has a 47.28% 10-dB return-loss bandwidth and only occupies a 20.89% circuit size of the conventional one. By considering the 180° ± 5° phase difference, the frequency range covers from 28.73 to 39.53 GHz with a 31.6% relative bandwidth. Over this frequency range, the amplitude imbalance varies from - 0.269 to 0.8 dB.

Keywords

III-V semiconductors; MIMIC; MMIC; coplanar waveguides; gallium arsenide; high electron mobility transistors; losses; waveguide couplers; GaAs; MMIC technology; RRC; asymmetrical coplanar-waveguide T-structure; compact Ka-band CPW rat-race coupler; compact circuit footprint; frequency 28.73 GHz to 39.53 GHz; gain -0.269 dB to 0.8 dB; loss 10 dB; output phase response; pHEMTs process; phase difference; return-loss bandwidth; short-circuited quarter-wave stub; size 0.15 mum;

fLanguage

English

Journal_Title

Electronics Letters

Publisher

iet

ISSN

0013-5194

Type

jour

DOI

10.1049/el.2013.1478

Filename

6612796