Browsing by Author "Liao, Ching-Ku"

Now showing 1 - 14 of 14

A 1.5 to 37 GHz ultra-broadband MMIC Mouw's star mixer
(2005)
Chang, Chi-Yang
;
Liao, Ching-Ku
;
Niu, Dow-Chih
;
電信工程研究所
;
Institute of Communications Engineering
A MMIC ultra-broadband star mixer using Mouw's hybrid junction is presented in this paper. The MMIC chip uses 0.15 mu m HEMT process. The chip is measured in three mounting environments, namely, absorber backed, 15 mil Al(2)O(3) substrate plus absorber, and conductor backed and all of them show ultra-broadband performances. The measured results show that the bandwidth is from 1.5 to 37 GHz except a resonant dip near. 23 GHz occurs in conductor backed case.. The IF 3 dB bandwidth is from DC to 2.5 GHz. The chip can be used as either up- or down-converter. Because the spiral layout of the Mouw's hybrid junction shrinks the area significantly, no off chip baluns are required. The chip size is 2 mm by 2 mm.
A novel five-pole microstrip cascade quadruplet filter
(2005)
Liao, Ching-Ku
;
Chang, Chi-Yang
;
電信工程研究所
;
Institute of Communications Engineering
A five-pole cascade quadruplet microstrip filter is presented. The source and load of the filter couple to two resonators respectively, which establishes two independent quadruplet blocks to control two independent pair of finite transmission zeros. The proposed tuning fingers are introduced to effectively control the strength of cross couplings. Compared to the eight-pole CQ filter, the proposed five-pole CQ filter provides an alternative choice of the filter with two pairs of transmission zeros but has less passband insertion loss. Both simulated and experimental results are given.
A reconfigurable filter based on doublet configuration
(2007)
Liao, Ching-Ku
;
Chang, Chi-Yang
;
Lin, Jenshan
;
電信工程研究所
;
Institute of Communications Engineering
A surrogate model is proposed to model a previously published second-order tunable filter. The surrogate model can be represented by a coupling matrix in a doublet configuration, and a simple method based on the even-odd mode bisection is given to extract the coupling matrix. From the extracted parameters, one can decide how to design a filter with prescribed quasi-elliptic responses and how to adjust varactors to reconfigure the response. Using the proposed methods, the second-order filter can be configured to have a finite transmission zero on either the lower side or the upper side of the passband in a prescribed location even when the center frequency of the filter is tuned. Both simulated and measured results of an example are presented.
A vector-fitting formulation for parameter extraction of lossy microwave filters
(2007-04-01)
Liao, Ching-Ku
;
Chang, Chi-Yang
;
Lin, Jenshan
;
電信工程研究所
;
Institute of Communications Engineering
In this letter, a formulation based on the vector fitting is applied to extract the equivalent circuit model from the frequency response of lossy cross-coupled microwave filters. By approximating the lossy response with short-circuit admittance parameters in partial fractional expansion form, the proposed method can evaluate the unloaded quality factor of resonators and extract the transversal coupling matrix simultaneously. The methodology of the vector fitting can identify the poles and residues of the short-circuit admittance parameters even when the poles are on the complex plane. And the extracted transversal coupling matrix can further transform into the prescribed form corresponding to the physical layout. The proposed method can be used in the tuning process of filter designs where the extraction of a coupling matrix is essential. To verify the method, a cross-coupled quadruplet filter is used as an example.
Dual-Band Filters with Frequency-Separated Dual-Path Coupling Scheme
(2010-01-01)
Kuo, Yi-Ting
;
Lu, Jhe-Ching
;
Liao, Ching-Ku
;
Chang, Chi-Yang
;
電信工程研究所
The dual-path topology is provided for dual-band filter design. The frequency-separated property is analyzed, and it shows the capability to design the filtering function separately in each path. Moreover, the dual-path topology is compatible with both symmetric and asymmetric dual-band characteristic. Two microstrip implementations are provided to demonstrate the reliability of dual-path dual-band topology.
Five-Pole Parallel-Coupled Microstrip Cascade Quadruplet Filters for High Selectivity and Flat Group Delay
(2009)
Lu, Jhe-Ching
;
Lin, Yun-Wei
;
Liao, Ching-Ku
;
Chang, Chi-Yang
;
電信工程研究所
The design of five-pole cascade quadruplet microstrip filters is presented. Based on a conventional parallel-coupled structure, good initial physical dimensions can be obtained by the well-known analytical method. Applying source and load to couple to the third resonator two cascaded quadruplets are formed. Two pairs of transmission zeros can be independently located on either real or imaginary frequency axes. Two filters are introduced in this paper that one have two pairs of real frequency transmission zeros for selectivity, and the other have one pair of real frequency transmission zeros for selectivity and another pair of imaginary frequency transmission zeros for group delay equalization. The flat group delay response is particularly sensitive to the unwanted cross coupling. The proposed structure solves this problem and shows a very flat group delay in the passband. The simulated and measured results of the two designed microstrip filters are well-matched.
High Selectivity and Flat Group Delay ParallelCoupled Microstrip Bandpass Filter with Lumped Element K-Inverters
(2010-01-01)
Lin, Yun-Wei
;
Lu, Jhe-Ching
;
Chang, Chi-Yang
;
Liao, Ching-Ku
;
電信工程研究所
In this paper, high selectivity and flat group delay parallel-coupled microstrip bandpass filter with lump element Kinverter are proposed. By using delay line, cross coupling is introduced and controlled easily to generate finite transmission zeros for selectivity and flat group delay. Finally, 5th-order and 6th-order filters with high selectivity and flat group delay are given as examples.
Microstrip band-pass filters with wide stopband and sharper cutoff response
(2005)
Hsieh, Ming-Yu
;
Wang, Shih-Ming
;
Liao, Ching-Ku
;
Chiang, Chin-Hsien
;
Chang, Chi-Yang
In this paper, a microstrip band-pass filter (BPF) with the sharper cutoff rate and suppression of the 2(nd), 3(rd), and 4(th) harmonics is developed. The half wavelength transmission resonator with a pair of tap-connected open-ended stubs is adopted for constructing filter with band-edge attenuation poles. Using resistive attenuator and adequate coupling, structures can suppress the unwanted harmonics. The resonance characteristic of resonator with embedded attenuator is analyzed with the aid of unloaded quality factor. By means of controlling the coupling structures, the embedded resistive attenuator, and the resonator with tap-connected stubs, the proposed bandpass filters can easily achieve a wide stopband and a sharp skirt property. Band-pass filter of center frequency at 1.96GHz was implemented to confirm our ideas.
Microstrip parallel-coupled filters with cascade trisection and quadruplet responses
(2008-09-01)
Lu, Jhe-Ching
;
Liao, Ching-Ku
;
Chang, Chi-Yang
;
電信工程研究所
;
Institute of Communications Engineering
Microstrip parallel-coupled filters with generalized Chebyshev responses are presented. The basic structure of the proposed filter is a conventional parallel-coupled filter of which the physical dimensions can be easily obtained by the well-known analytical method. With the aid of the equivalent circuit corresponding to a conventional parallel-coupled filter, the relative insertion phase from source or load to each open end of resonators can be easily obtained by observing the two-port admittance matrix. Applying the cross coupling from source or load to a proper nonadjacent resonator, a trisection or a quadruplet coupling scheme can be realized with prescribed transmission zeros. More importantly, the proposed trisection can be designed to have a transmission zero on the lower or upper stopband by just adjusting the length of the cross-coupling strip. Using the proposed structure, the conventional time-consuming adjusting procedure to obtain initial physical dimensions of filters is no longer required. In this paper, a fourth-order parallel-coupled filter is used as the basic structure to demonstrate various combinations of transmission zeros. Simulated and measured results are well matched.
Microstrip realization of generalized Chebyshev filters with box-like coupling schemes
(2007-01-01)
Liao, Ching-Ku
;
Chi, Pei-Ling
;
Chang, Chi-Yang
;
電信工程研究所
;
Institute of Communications Engineering
This paper presents generalized Chebyshev microstrip filters with box-like coupling schemes. The box-like coupling schemes taken in this paper include a doublet, extended doublet, and fourth-order box section. The box-like portion of the coupling schemes is implemented by an E-shaped resonator. Synthesis and realization procedures are described in detail. The example filters show an excellent match to the theoretical responses.
New Multiband Coupling Matrix Synthesis Technique and Its Microstrip Implementation
(2010-07-01)
Kuo, Yi-Ting
;
Lu, Jhe-Ching
;
Liao, Ching-Ku
;
Chang, Chi-Yang
;
電機工程學系
In this paper, we present a novel analytical multiband transversal coupling matrix synthesis technique. By properly combining several single-band filtering functions, the multiband filtering function with flexible transmission zeros and various bandwidth are available. The transversal coupling scheme is then transformed into a practically realizable coupling scheme. To verify the feasibility of the proposed method, two dual-band coupling schemes, both single-path and dual-path, are proposed as examples of the dual-band filter design. Finally, the dual-band filter, based on the coupling matrix corresponding to a specific coupling scheme, can be realized using a microstrip parallel-coupled structure.
Novel multifold finite-ground-width CPW quarter-wavelength filters with attenuation poles
(2007-01-01)
Chen, Chin-Hsuing
;
Liao, Ching-Ku
;
Chang, Chi-Yang
;
電信工程研究所
;
Institute of Communications Engineering
This paper proposes a novel multifold finite-ground-width coplanar waveguide (CPW) lambda/4 resonator filter that has the capability of realizing attenuation poles by cross coupling of nonadjacent resonators. The newly proposed multifold structures not only greatly shrink the length of a resonator, but also provide a convenient way to implement cross coupling in a filter. The proposed multifold finite-ground-width CPW resonators can have much stronger coupling than that of spiraling and meandering layouts, and any number of folds is possible. Two combline filters are designed and measured with twofold and threefold lambda/4 finite-ground-width CPW resonators. A trisection and a quadruplet generalized Chebyshev filter formed by cross couplings between nonadjacent resonators have been implemented by modifying the layout of the resonator. These filters are smaller in size and have the capability of controlling attenuation poles.
Quarter-Wave Parallel-Coupled and Interdigital Microstrip Bandpass Filters with Generalized Chebyshev Response
(2010-01-01)
Lin, Yun-Wei
;
Lu, Jhe-Ching
;
Chang, Chi-Yang
;
Liao, Ching-Ku
;
電信工程研究所
Two quarter-wave resonator microstrip bandpass filters with generalized chebyshev response are proposed in this work. By using the delay lines and observing the phase relationship between source and resonators, the phase and amplitude of cross couplings can be easily realized so that a generalized chebyshev response can be implemented. Furthermore, the cross coupling for interdigital structure is proposed. Finally, a 3rd-order high selectivity quarter-wave filter and a 5th-order high selectivity and flat group delay interdigital filter are fabricated to show the feasibility.
Six-Pole Parallel-Coupled Microstrip CQ Filter with Source-Load and Source/Load to Resonator Cross Coupling
(2009)
Lin, Yun-Wei
;
Lu, Jhe-Ching
;
Chang, Chi-Yang
;
Liao, Ching-Ku
;
電信工程研究所
The six-pole cascade quadruplet microstrip filter with source-load and source/load to nonadjacent resonator cross coupling is proposed to achieve generalized Chebyshev responses. The presented coupling scheme achieves similar skirt selectivity as that of a sixth-order fully canonical form filter. In addition, the proposed filter is less sensitive than that of canonical form filter. The initial design can be easily obtained by the design procedure of conventional parallel-coupled filter. With source to the third resonator and load to the fourth resonator cross couplings, two quadruplets are formed. Moreover, a source-load cross coupling forms the third quadruplet. The three quadruplets produce three pairs of finite transmission zeros. By controlling the strength of the cross couplings, the position of the three pairs of zeros can be decided arbitrarily. A design example is provided in this paper. Furthermore, simulation and measurement results are well matched.