Ruey-Beei Wu

Design of Dual- and Triple-Passband Filters Using Alternately Cascaded Multiband Resonators

A novel method for designing multiband bandpass filters has been proposed in this paper. Coupling structures with both Chebyshev and quasi-elliptic frequency responses are presented to achieve dual- and triple-band characteristics without a significant increase in circuit size. The design concept is to add some extra coupled resonator sections in a single-circuit filter to increase the degrees of freedom in extracting coupling coefficients of a multiband filter and, therefore, the filter is capable of realizing the specifications of coupling coefficients at all passbands. To verify the presented concept, four experimental examples of filters with a dual-band Chebyshev, triple-band Chebyshev, dual-band quasi-elliptic, and triple-band quasi-elliptic response have been designed and fabricated with microstrip technology. The measured results are in good agreement with the full-wave simulation results

Microstrip diplexers design with common resonator sections for compact size, but high isolation

High isolation and compact size microstrip diplexers designed with common resonator sections have been proposed. By exploiting the variable frequency response of the stepped-impedance resonator, resonators can be shared by the two filter channels of the desired diplexer if their fundamental and the first spurious resonant frequency are properly assigned. Size reduction are, therefore, achieved by introducing a few common resonator sections in the circuit. This concept has been verified by the experimental results of two diplexer circuits. One of the diplexers is composed of two three-pole parallel-coupled bandpass filters and the other is composed of two four-pole cross-coupled bandpass filters, which are formed by only five and six resonators, respectively. Both of them occupy extremely small areas while still keeping good isolations. Good agreements are also achieved between measurement and simulation.

Design of microstrip bandpass filters with multiorder spurious-mode suppression

This paper proposes a bandpass filter design method for suppressing spurious responses in the stopband by choosing the constitutive resonators with the same fundamental frequency, but staggered higher order resonant frequencies. The design concept is demonstrated by a four-pole parallel-coupled Chebyshev bandpass filter and a compact four-pole cross-coupled elliptic-type bandpass filter. Each filter is composed of four different stepped-impedance resonators (SIRs) for which a general design guideline has been provided in order to have the same fundamental frequency and different spurious frequencies by proper adjusting the impedance and length ratios of the SIR. Being based on knowledge of the coupling coefficients and following the traditional design procedure, the resultant filter structures are simple and easy to synthesize. The measured results are in good agreement with the simulated predictions, showing that better than -30-dB rejection levels in the stopband up to 5.4f/sub 0/ and 8.2f/sub 0/ are achieved by the Chebyshev and quasi-elliptic filters, respectively.

Miniaturized Bandpass Filters With Double-Folded Substrate Integrated Waveguide Resonators in LTCC

This paper proposes miniaturized bandpass filters with double-folded substrate integrated waveguide (SIW) resonators using multilayer low-temperature co-fired ceramic (LTCC) technology. Formed by inserting a metal plate with two orthogonal slots into the cavity, the double-folded SIW resonator is used for the circuit size reduction with its footprint about a quarter of the conventional TE101 mode. With LTCC technology, there is more flexibility to organize the cavities of filters because of the 3-D arrangement. The vertically stacked cavities are coupled by ldquoLrdquo- or ldquoUrdquo-shaped slots, and if arranged horizontally, by an inductive window on the common sidewall or a suspended stripline between the cavities. Through experimental measurements and simulations at both the Ka- V -bands, it has been demonstrated that the proposed filter has compact sizes and good frequency responses. The area of the fully stacked Chebyshev filter has 88% size reduction in comparison with a three-pole planar waveguide filter, while the vertically stacked quasi-elliptic filter has 74% size reduction in comparison with a four-pole planar waveguide filter.

Coplanar waveguide bandpass filter-a ribbon-of-brick-wall design

This paper proposes a novel ribbon-of-brick-wall design of the coplanar waveguide bandpass filter which is built from cascading several sections of quarter wavelength open-end series stubs. The design originates from modeling the series stub as a system of two asymmetrically coupled transmission lines, which is then made equivalent to a basic filter element of admittance inverter. The relationship between the parameters of the coupled transmission lines and the admittance inverter is derived and the design charts are provided for the convenience of the designers. Systematic procedure is established to design the Chebyshev filter, which is also fabricated and measured. In addition, the quasistatic equivalent lumped circuit models of the discontinuities formed between two sections are evaluated and incorporated into the circuit simulation to get better prediction for the filter performance. The good agreement between simulation results and experimental data justifies the design procedure and validates the present analysis approach. >

60-GHz Four-Element Phased-Array Transmit/Receive System-in-Package Using Phase Compensation Techniques in 65-nm Flip-Chip CMOS Process

AThe 60-GHz four-element phased-array transmit/receive (TX/RX) system-in-package antenna modules with phase-compensated techniques in 65-nm CMOS technology are presented. The design is based on the all-RF architecture with 4-bit RF switched LC phase shifters, phase compensated variable gain amplifier (VGA), 4:1 Wilkinson power combining/dividing network, variable-gain low-noise amplifier, power amplifier, 6-bit unary digital-to-analog converter, bias circuit, electrostatic discharge protection, and digital control interface (DCI). The 2 × 2 TX/RX phased arrays have been packaged with four antennas in low-temperature co-fired ceramic modules through flip-chip bonding and underfill process, and phased-array beam steering have been demonstrated. The entire beam-steering functions are digitally controllable, and individual registers are integrated at each front-end to enable beam steering through the DCI. The four-element TX array results in an output of 5 dBm per channel. The four-element RX array results in an average gain of 25 dB per channel. The four-element array consumes 400 mW in TX and 180 mW in RX and occupies an area of 3.74 mm2 in the TX integrated circuit (IC) and 4.18 mm2 in the RX IC. The beam-steering measurement results show acceptable agreement of the synthesized and measured array pattern.

Modeling of microwave active devices using the FDTD analysis based on the voltage-source approach

This letter describes a voltage-source-based formulation of the extended finite-difference time-domain algorithm for the purpose of modeling microwave devices. The device-wave interaction is fully characterized by replacing the lumped devices with equivalent voltage sources in the device region, which in turn generate electromagnetic fields according to Faradays law. This formulation is applied to the analysis of a typical microwave amplifier, which includes a three-terminal active MESFET device. Simulation results are in good agreement with measured data.

Millimeter-wave MMIC passive HEMT switches using traveling-wave concept

This paper describes the design of millimeter-wave wide-band monolithic GaAs passive high electron-mobility transistor (HEMT) switches using the traveling-wave concept. This type of switch combined the off-state shunt transistors and series microstrip lines to form an artificial transmission line with 50-/spl Omega/ characteristic impedance. A 15-80-GHz single-pole double-throw (SPDT) switch in conjunction with quarter-wavelength impedance transformers demonstrates an insertion loss of less than 3.6 dB and an isolation of better than 25 dB. Another type of wide-band switch was designed by using a series HEMT switch to replace the quarter-wavelength transformer, and the operating band can be extended to dc. With this scheme, dc-80-GHz single-pole single-throw (SPST) and dc-60-GHz SPDT switches are also developed with compact chip size. From dc to 80 GHz, the insertion loss and isolation of the SPST switch are better than 3 and 24 dB, respectively. The SPDT switch has an insertion loss of better than 3 dB and an isolation of better than 25 dB from dc to 60 GHz. The analysis of circuit characteristics and design procedures are also included. It is concluded that the device periphery can be selected for the desired bandwidth, while the number of transistors is decided to achieve the isolation.

Design of Vertically Stacked Waveguide Filters in LTCC

This paper proposes four-pole quasi-elliptic function bandpass waveguide filters using multilayer low-temperature co-fired ceramic technology. The vertical metal walls of the waveguide resonators are realized by closely spaced metallic vias. Adjacent cavities are coupled by a narrow slot at the edge of the common broad wall or an inductive window on the sidewall. Two types of vertical coupling structures are utilized to achieve the cross coupling between nonadjacent resonators at different layers. With multilayer capability, there is more flexibility to arrange the cavities of coupled resonator filters in 3-D space. It is demonstrated by both the simulation and experiment that the proposed filter structures occupy a compact circuit area and have good selectivity. The filter with electric field cross coupling occupies a half area of a planar four-pole waveguide filter, while the filter with stacked vias cross coupling has 65% size reduction in comparison with a planar waveguide filter.

Hybrid finite-difference time-domain modeling of curved surfaces using tetrahedral edge elements

A hybrid finite-difference time-domain (FDTD) method is proposed for solving transient electromagnetic problems associated with structures of curved surfaces. The method employs the conventional FDTD method for most of the regular region but introduces the tetrahedral edge-based finite-element scheme to model the region near the curved surfaces. Without any interpolation for the fields on the curved surface, nor any additional stability constraint due to the finer division near the curved surfaces, the novel finite-element scheme is found to have second-order accuracy, unconditional stability, programming ease, and computational efficiency. The hybrid method is applied to solve the electromagnetic scattering of three-dimensional (3-D) arbitrarily shaped dielectric objects to demonstrate its superior performance.