A broadband MMIC quadrature coupler using a braided microstrip structure

Author

Willems, D.A.

Author_Institution

ITT Aerosp./Commun., Fort Wayne, IN, USA

fYear

1994

fDate

23-27 May 1994

Firstpage

899

Abstract

This paper presents a broadband quadrature coupler implemented with a unique braided microstrip structure. This novel structure consists of 64 air bridge crossovers and is completely compatible with MMIC processing, employing only the processing steps required to fabricate MIM capacitors. The airbridge crossovers create extremely tight coupling coefficients which are independent of the substrate thickness and, therefore, can be used on the thin substrates employed for MMICs. This paper contains the test results of a 2.5 to 8 GHz coupler fabricated on a 125 /spl mu/m GaAs substrate. The coupler achieved less than /spl plusmn/25 dB of amplitude imbalance with better than 17 dB return loss and 11 dB of isolation over the almost 2 octave bandwidth. This bandwidth and performance are the best reported for braided structures on thin GaAs substrates.<>

Keywords

III-V semiconductors; MMIC; gallium arsenide; metal-insulator-metal structures; microstrip components; waveguide couplers; 125 micron; 17 dB; 2.5 to 8 GHz; GaAs; GaAs substrate; MIM capacitors; MMIC; air bridge crossovers; amplitude imbalance; braided microstrip structure; broadband quadrature coupler; coupling coefficients; isolation; return loss; Bandwidth; Bridges; Gallium arsenide; MIM capacitors; MMICs; Microstrip; Testing;

fLanguage

English

Publisher

ieee

Conference_Titel

Microwave Symposium Digest, 1994., IEEE MTT-S International

Conference_Location

San Diego, CA, USA

ISSN

0149-645X

Print_ISBN

0-7803-1778-5

Type

conf

DOI

10.1109/MWSYM.1994.335212

Filename

335212