Browsing by Author "Hsu, Ching-Luh"

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A two-stage SIR bandpass filter with an ultra-wide upper rejection band
(2007-01-01)
Hsu, Ching-Luh
;
Kuo, Jen-Tsai
;
電信工程研究所
;
Institute of Communications Engineering
Two-stage stepped-impedance resonator (SIR) filters are designed to have a wide upper stopband. Two transmission zeros are also created near the passband to form a quasi-elliptic response. For a 20-dB rejection level, with properly designed SIR geometry and tapped-line structure, the leading three spurious re nances of the SIR are suppressed by transmission zeros and respective unmatched singly loaded Q (Q(si)) values. Measured results illustrate that stopbands up to 8.4 and 5.3 times the design frequency can be achieved for rejection levels of 20 and 30 dB, respectively.
Compact planar quasi-elliptic function filter with inline stepped-impedance resonators
(2007-08-01)
Kuo, Jen-Tsai
;
Hsu, Ching-Luh
;
Shih, Eric
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電信工程研究所
;
Institute of Communications Engineering
Compact microstrip bandpass filters of orders N = 4,6, and 8 with quasi-elliptic function responses are synthesized with inline stepped-impedance resonators. The filters have enhanced transition responses since two transmission zeros are generated on both sides of the passband. Existence of these two zeros is investigated by formulating the Y-matrix of the equivalent circuit for the filter and taking adjacent and nonadjacent coupling into account. Some matrix elements Y-j,Y-j+2 representing coupling between two nonadjacent resonators are shown to have the opposite signs in both the lower and upper sides of the center frequency. This property leads to creation of the two transmission zeros on both sides of the passband. It is demonstrated that one more zero can be created in the rejection band by the tapped-line input/output scheme. Experimental circuits on substrates with epsilon(r) = 2.2 and 10.2 are measured to validate the theory and design.
Control of Transmission Zero by Mixed-Coupling in a Two-Stage Coupled-Resonator Filter
(2007)
Hsu, Ching-Luh
;
Yu, Cheng-Hsuan
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Kuo, Jen-Tsai
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電信工程研究所
;
Institute of Communications Engineering
A transmission zero is generated near the passband for the filter consisting of two coupled resonators. The transmission zero can be placed in upper or lower rejection bands by designing the electric and magnetic components of the inter-resonator coupling. An equivalent circuit is developed for explaining the creation of zero and the control of filter bandwidth. Y-matrix parameters of the proposed equivalent circuit are formulated. The electric and magnetic components of the coupling associated with parallel-coupled half-wavelength microstrip resonators are extracted for the purpose of filter synthesis. For validating the theory, two experimental filters based on microstrip resonators with mixed-coupling structures are designed and measured.
Design of cross-coupled quarter-wave SIR filters with plural transmission zeros
(2006)
Hsu, Ching-Luh
;
Kuo, Jen-Tsai
;
電信工程研究所
;
Institute of Communications Engineering
A cross-coupled bandpass filter is designed with quarter-wave stepped-impedance resonators (SIRS) on a single circuit plane. The entire circuit has not only a compact area since half-sized SIRS are used, but also a wide upper stopband because the first spurious peak occurs at a frequency much higher than the passband. Plural transmission zeros on both sides of the passband can be realized by non-adjacent couplings and tapped input/output. Two-port Z-parameters are employed to formulate the analysis of the transmission zeros. An experimental filter is fabricated and measured to validate the design.
Design of Dual-Band Branch Line Couplers With Circuit Miniaturization
(2008)
Hsu, Ching-Luh
;
Kuo, Jen-Tsai
;
電信工程研究所
;
Institute of Communications Engineering
Design of a dual-band branch line coupler with a very compact size is proposed. For reducing circuit area, stepped-impedance sections are used. Folded open stubs are attached to each stepped-impedance section at its both ends for the dual-band purpose. Circuit dimensions and geometrics are designed in order to achieve the best circuit miniaturization. For validation, measured results of an experimental circuit are compared with simulation data.
Design of dual-band microstrip rat race coupler with circuit miniaturization
(2007)
Hsu, Ching-Luh
;
Chang, Chin-Wei
;
Kuo, Jen-Tsai
;
電信工程研究所
;
Institute of Communications Engineering
Rat race ring coupler with stepped-impedance sections is designed to have a dual-band characteristic. This is realized by attaching open stubs to both ends of each stepped-impedance section to create a phase of 90 degrees at two designated frequencies. Transcendental equations are derived for solving impedance ratio R and lengths of the stepped-impedance sections. Circuit with miniaturized area can be obtained if R > 1. is chosen. Such microstrip ring hybrids operating at 2.45/5.2 GHz with R = 1 and R = 4 are designed and fabricated. Experiments are performed to confirm the theory.
Design of loop resonator filters with a dual-passband response
(2005)
Hsu, Ching-Luh
;
Kuo, Jen-Tsai
;
Hsu, Fu-Chieh
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電信工程研究所
;
Institute of Communications Engineering
Design method is presented for loop resonator fliters with a dual-passband response. The loop resonator is equipped with stepped-impedance junctions, so that its second passband can be tuned, relative to the fundamental frequency f(1), by its geometric parameters. Analysis of the resonant characteristics of a loop resonator is formulated by the transmission line theory. Through proper tapped input/output couplings, bandpass filters with a dual-passband response can be achieved. Measured results of two fabricated circuits show good agreement with the simulation.
Miniaturized Dual-Band Hybrid Couplers With Arbitrary Power Division Ratios
(2009-01-01)
Hsu, Ching-Luh
;
Kuo, Jen-Tsai
;
Chang, Chin-Wei
;
電信工程研究所
;
Institute of Communications Engineering
Branch-line and rat-race couplers are designed to have dual-band operation with arbitrary power division ratios. An elementary two-port is proposed to imitate the 90 degrees section at the two designated frequencies with different characteristic impedances. The two-port consists of a stepped-impedance section with open stubs attached to its two ends, and its circuit parameters are determined by the transmission line theory. The use of the stepped-impedance sections also leads to circuit miniaturization. By the standard microstrip technology., investigated also includes the realizable power division ratios and circuit bandwidths in the two bands, the upper limit of the ratio of the two designated frequencies and the miniaturization factor of the proposed circuit. Hybrid couplers operating at 2.45/5.2 GHz with various power division ratios are designed, fabricated and tested. Experiment results are compared with the theory and simulation.