| Summary: | 碩士 === 國立中央大學 === 電機工程研究所 === 96 === Abstract
In this study, two kinds of on-chip bandpass filters are proposed and
implemented using the GaAs pHEMT process. They are very suitable for the design
of GaAs single-chip transceiver. For the Q-Band bandpass filter with wide bandwidth
from 31.3 to 45GHz, the novel planar coupled-line filters with step-impedance
resonators are proposed. The resonators can be made much smaller than conventional
quarter-wavelength resonators. Compared to the conventional parallel-coupled
bandpass filters that are based on quarter-wavelength resonators, the circuit size of
proposed filters are reduced by more than 1/4. In addition, by utilizing the inherent
transmission zeros resulted from cross-coupling, the rejection at 29GHz is better than
37 dB . The proposed Q-Band filters meet the requirements of ALMA Band-1 radio
telescope receiver, and have the advantages of reducing size, weight, and complexity
in system integration. On the other hand, for the K-Band bandpass filter with narrow
bandwidth from 24 to 26GHz, the planar hairpin-line filters with loaded capacitors are
proposed. The circuit size of this filter can be reduced by half compared to
conventional hairpin-line bandpass filters. The 30dB stopband bandwidth of
proposed K-Band filter can be extended up to 4.6fo . In addition, a WR22
waveguide-based Q-Band bandpass filter is also implemented for bench-marking.
In order to verify the effectiveness of proposed filter design equations and
procedure, two planer bandpass filters with bandwidths from 2.3~2.7GHz are also
fabricate on PCB. For the step-impedance design, the 30 dB stopband bandwidth is
up to 7.6fo . For the hairpin filter with loaded capacitor, the length of coupled-line can
be reduced to λ/12 . All the measurement results agree well with the simulation ones.
In this work, the characteristics of different kinds of coupled-line sections are
thoroughly investigated so as to make the best use of them in bandpass filter designs.
Simple and explicit design flows have also been proposed for all designs, which allow
the easy extension of proposed filter structures for further improvement in the future.
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