| dc.description.abstract | In this thesis, compact Wilkinson power divider and Butler matrix are designed with no
bandwidth reduction. Traditional Wilkinson power divider and branch-line coupler are
composed of many quarter-wavelength transmission-line sections at a designated frequency.
However, at the lower frequencies of the microwave band, the sizes of conventional
Wilkinson power divider and branch-line coupler are too large for practical use.
Conventionally, there are two ways to reduce the size of transmission lines. The first one is
achieved by using the folded line configuration, but the resultant circuit area is still large. The
other is accomplished by adopting lumped-element components, such as using the T or π
equivalent model, may be employed to reduce the circuit size, however these equivalent
models are useful only in a narrow bandwidth around the center frequency. In order to expand
the applicable frequency range of the equivalent circuit, this thesis adopts the modified-T
model for the λ/4 lines, so that the very compact designs may be implemented with no
bandwidth reduction. The proposed circuit designs are accomplished by adopting balance
inductors and metal-insulator-metal (MIM) capacitors so these designs may be suitable for
MMIC applications.
This thesis presents a compact 2.5GHz Wilkinson power divider, which is fabricated by
GaAs, shows the circuit size of 0.020λg × 0.034λg, and a compact 2.5GHz branch-line coupler,
which is fabricated by Glass Integrated Passive Device (GIPD), shows the circuit size of
0.021λg × 0.022λg. The circuit size is really small compared with traditional ways, and these
deigns are no bandwidth reduction. In addition, a compact 2.5GHz 4 × 4 Butler matrix, which
is fabricated by GIPD, is presented. The circuit size is 0.044λg × 0.047λg and the bandwidth is
34% (|S11| > 10 dB). A compact two section Wilkinson power divider is also presented in
GaAs process. The circuit size is 0.044λg × 0.078λg and the bandwidth is 129.1% (|S11| > 15
dB).
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