A Modified λ0/4 Short-Circuited Stub Bandpass Filter for UWB Applications Utilizing LTCC Technology

Thai Hoa DUONG
Kye San LEE
Ihn S. KIM

Publication
IEICE TRANSACTIONS on Communications   Vol.E93-B    No.5    pp.1163-1171
Publication Date: 2010/05/01
Online ISSN: 1745-1345
DOI: 10.1587/transcom.E93.B.1163
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Devices/Circuits for Communications
Keyword: 
short-circuited stub,  bandpass filter,  ultra-wideband (UWB),  low characteristic impedance,  LTCC,  WLAN stopband,  

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Summary: 
In this paper, we utilize low temperature co-fired ceramic technology (LTCC) to realize a modified short-circuited stub bandpass filter suitable for ultra-wideband (UWB) applications. By modifying the conventional short-circuited stub bandpass filter structure with stubs and connecting lines of lower characteristic impedances, the number of stubs has been reduced from 5 to 2 on a high dielectric constant substrate (∈ r = 40). A wireless local area network (WLAN) stopband in the frequency range of 5.15 to 5.825 GHz has been inserted into the filter characteristic using three short-circuited coupled lines. The filter is fabricated and measurement results show that it has an insertion loss less than 1.0 dB and return loss better than 10 dB in the pass bands. A bandwidth ratio of 109.49% has been achieved. Measurement results agree well with simulation results. The dimensions of the filter are 480.57 mm3.