Browsing by Author "Chang, Wei-Shin"

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A High Slow-Wave Factor Microstrip Structure With Simple Design Formulas and Its Application to Microwave Circuit Design
(2012-11-01)
Chang, Wei-Shin
;
Chang, Chi-Yang
;
傳播研究所
;
Institute of Communication Studies
This paper proposes a new microstrip slow-wave structure. The unit cell comprises a Schiffman section of meander line and a shunt open-circuited stub. No via-holes and ground-plane patterns are required. Simple design formulas can be used to obtain line parameters, such as the characteristic impedance and phase velocity. According to the analysis, the characteristic impedance and slow-wave factor of the proposed slow-wave line can be independently controlled by merely two layout parameters. The proposed uniplanar structure only requires a single-layer substrate and is simply constructed using the conventional printed circuit board manufacturing process. A branch-line and a rat-race coupler were designed and fabricated using the proposed structure to demonstrate its feasibility. Their sizes are only 8.49% and 4.87% of the conventional ones, respectively. This novel slow-wave structure should find wide applications in compact microwave circuits.
Analytical Design of Microstrip Short-Circuit Terminated Stepped-Impedance Resonator Dual-Band Filters
(2011-07-01)
Chang, Wei-Shin
;
Chang, Chi-Yang
;
電信工程研究所
;
Institute of Communications Engineering
This paper proposes an analytical method to design a dual-band filter using the short-circuit terminated half-wavelength stepped-impedance resonator (SIR). The SIR has an advantage to easily control the first and second resonances by adjusting its structural parameters. In the proposed method, the structural parameters of the SIR are obtained analytically according to the two passband center frequencies and bandwidths of the filter. As a result, the achievable specifications of the dual-band filter can be rapidly determined. The coupling between adjacent SIRs is realized by a short-circuited stub, which is characterized as a K-inverter network. The dual-frequency transformer incorporated with the tapped-line input/output structure is used for the external coupling. Applying the analytical equations in the design process, a dual-band filter can be easily and quickly realized. More importantly, compared to the published dual-band filters, the proposed method is easier to design, especially for a relatively high-order dual-band filter. Two fourth-order and one sixth-order dual-band filters are designed and fabricated to demonstrate the proposed method.
CMOS Impedance Transforming Balun Filter with Improvement of Magnetic Coupling to Nearby Spiral Inductors
(2011-01-01)
Huang, Peng-Da
;
Chang, Wei-Shin
;
Chang, Chi-Yang
;
Wan, Shih-Ming
;
Chen, Cheng-Chung
This paper presents a novel balun filter in TSMC 0.18 mu m CMOS technology which can suppress the magnetic coupling with nearby on-chip spiral inductors. The proposed balun filter keeps major requirements of a traditional coupled spiral inductor balun used in the output stage of a PA (power amplifier) such as center tap for DC bias, controllable impedance transformation ratio, good out-of-phase performance, etc. This new structure can achieve a maximum of 18 dB suppression of magnetic coupling to the nearby spiral inductor.
Compact Microstrip Bandpass Filters Using Miniaturized Quarter-Wavelength Resonators
(2010-01-01)
Liang, Cheng-Hsien
;
Chang, Wei-Shin
;
Chang, Chi-Yang
;
電信工程研究所
;
Institute of Communications Engineering
This paper proposes a novel miniaturized lambda/4 microstrip resonator. The two shorted high-impedance lines not only possess the feasibility to be arranged but also provide the strong magnetic coupling between resonators easily. By applying the proposed resonator, the filter with the flexible bandwidth can be realized. Moreover, the spurious frequency can be shifted to the higher frequency by adjusting the structural parameters. The proposed lambda/4 resonator has a much smaller size compared to the conventional one. Two four-pole bandpass filters were designed and fabricated to demonstrate the practicality of the proposed resonator. Each filter occupies a small circuit area and has a good stopband response.
Compact Microstrip Bandpass Filters Using Miniaturized Slow-Wave Quarter-Wavelength Resonators
(2010-01-01)
Chang, Wei-Shin
;
Liang, Cheng-Hsien
;
Chang, Chi-Yang
;
電信工程研究所
;
Institute of Communications Engineering
This paper proposes a novel lambda/4 microstrip slow wave resonator with interdigital capacitive fingers. The interdigital fingers provide a strong capacitive loading so as to miniaturize the resonator size. The resonant frequency is easily adjusted by varying the number of fingers and the spacing between fingers. To demonstrate the feasibility of the proposed structure, one four-pole Chebyshev and one four-pole generalized Chebyshev filter with 0.05 dB equal-ripple bandwidths of 7.5% and 5%, respectively, were designed and fabricated. An extra transmission zero can be close to the passband for high selectivity and stopband attenuation by using the proposed slow-wave resonator and the tapped input/output structure. Both filters are compact in size and exhibit good stopband rejection.
Enhanced Coupling Structures for Tight Couplers and Wideband Filters
(2011-03-01)
Liang, Cheng-Hsien
;
Chang, Wei-Shin
;
Chang, Chi-Yang
;
電信工程研究所
;
Institute of Communications Engineering
Tightly coupled lines are difficult to realize on the conventional printed circuit board (PCB). This paper proposes two types of novel enhanced coupled-line structures appropriate for tightly coupled directional couplers and wideband filters. The proposed coupled-line structures both have a rectangular ground-plane aperture and two inserted signal strips in the aperture to increase the coupling strength significantly. No fine lines and narrow gaps are required so as to fit the conventional PCB fabrication process. More importantly, the proposed structures only need a single-layer substrate. To demonstrate the feasibility of the proposed structures, one 3-dB directional coupler and two four-pole Chebyshev filters with 0.05-dB equal-ripple bandwidths of 40% and 37% are designed and realized. The coupler and filters are fabricated on a PCB substrate with a dielectric constant of 3.58 and a thickness of 0.508 mm. Good agreement between measurements and simulations is observed.
Novel Low-Impedance Microstrip Structures for Miniaturized Microstrip Quarter-Wave Stepped-Impedance Resonator Filters
(2008)
Liang, Cheng-Hsien
;
Chang, Wei-Shin
;
Chang, Chi-Yang
;
電信工程研究所
;
Institute of Communications Engineering
Novel Microstrip Periodic Structure and Its Application to Microwave Filter Design
(2011-03-01)
Chang, Wei-Shin
;
Chang, Chi-Yang
;
電信工程研究所
;
Institute of Communications Engineering
This letter proposes a new type of microstrip slow-wave structure. The proposed structure has the signal strips and the inserted ground strips periodically loaded in the internal part of the conventional microstrip line. The proposed microstrip line has not only the same outline contour but also a lower phase velocity compared to the conventional one, especially for the thick substrate. In addition, the slow-wave factor and the characteristic impedance are easily varied by adjusting the structural parameters. A third-order Chebyshev filter with a passband ripple of 0.05 dB and a bandwidth of 10% was designed and fabricated using the proposed microstrip line. The simulated and measured results agree well with each other.
Slow-Wave Broadside-Coupled Microstrip Lines and Its Application to the Rat-Race Coupler
(2015-06-01)
Chang, Wei-Shin
;
Liang, Cheng-Hsien
;
Chang, Chi-Yang
;
傳播研究所
;
Institute of Communication Studies
This letter proposes a type of slow-wave broadside-coupled microstrip lines. The new structure only requires a single-layer substrate and has the independently controllable even-and odd-mode impedances and slow-wave factors by adjusting the corresponding structural parameters. This property greatly simplifies the circuit design. In addition, it provides a large coupling strength. A miniaturized wideband microstrip rat-race coupler with the high isolation and perfect balances is implemented using the proposed slow-wave coupled lines.