Hung-Wei Wu

Compact and Low Loss Dual-Band Bandpass Filter Using Pseudo-Interdigital Stepped Impedance Resonators for WLANs

In this letter, pseudo-interdigital stepped impedance resonators (PI-SIRs) are used to design the bandpass filter (BPF) with dual-band response. By tuning the impedance ratio (K) and physical length of SIRs, the BPF has good dual-passband performances at 2.4/5.2GHz and high isolation between the two passbands. It is shown that the dual-band BPF has a smaller area and lower insertion loss in comparison of previous works. Good agreement is shown between the full-wave electromagnetic simulation and the measurement

A New Quad-Band Bandpass Filter Using Asymmetric Stepped Impedance Resonators

A new quad-band microstrip bandpass filter (BPF) using asymmetric stepped impedance resonators (SIRs) is proposed. The filter only employs two sets of the asymmetric SIRs. One set is designed to operate at the first and third passbands (2.4/5.2 GHz) and the other set is employed at second and fourth passbands (3.5/6.8 GHz). By tuning the impedance and length ratios of the asymmetric SIRs, a multi-band filter can be easily achieved. This study provides a simple and effective method to design a quad-band filter with low insertion loss and compact size. Experimental verification is provided and good agreement has been found between simulation and measurement.

An Ultra-Wideband Bandpass Filter With an Embedded Open-Circuited Stub Structure to Improve In-Band Performance

In this letter, we present a compact ultra-wideband bandpass filter (BPF) with a notch band in the BPF performance by using an embedded open-circuited stub structure. The filter mainly consists of conventional stepped impedance resonator (SIR) as the multiple-mode resonator and two enhanced coupled input/output lines. The bandwidth can be analyzed by using the image-parameter method to obtain the proper dimension of the coupled lines and verified by using electromagnetic (EM) simulation. The embedded open-circuited stub structure in the SIR is used to produce a narrow notched band at 5.8 GHz, which its frequency position and bandwidth can be tuned by its physical parameters. The measured 3 dB fractional bandwidth of 113.8% and narrow notched band with 25 dB rejection is achieved. Good agreement between the EM simulation and measurement is obtained.

Compact microstrip bandpass filter with multispurious suppression

A compact microstrip bandpass fllter (BPF) with multispurious suppression is presented. The fllter consists of two coupled half-wavelength stepped impedance resonators (SIRs) and tapped input/output (I/O) lines. With tuning the impedance ratio (K) and length ratio (fi) of SIRs, a very wide stopband can be easily achieved. The fllter is designed at 2.4GHz (f0) with a wide stopband to 20GHz (8.16f0) and an average rejection level better than 25dB. This study provides a simple and efiective method to achieve a fllter with very wide stopband and compact circuit size simultaneously. Good agreement between the full-wave electromagnetic (EM) simulation and measurement is compared.

Multi-Layered Dual-Band Bandpass Filter Using Stub-Loaded Stepped-Impedance and Uniform-Impedance Resonators

The design of multi-layered dual-band bandpass filter using stub-loaded stepped-impedance and uniform-impedance resonators is proposed. The filter is designed to have dual-passband at 2.4, and 5.2 GHz for Wireless Local Area Network (WLAN). The multi-layered filter consists of the stub-loaded stepped-impedance resonator (SL-SIR) on the top layer and the stub-loaded uniform-impedance resonator (SL-UIR) on the bottom layer, that can provide the multi-path propagation to enhance the filter performance and compact circuit size. The proposed SL-SIR and SL-UIR play important roles for controlling the transmission zeros at each first and second passband edges. The measured results are in good agreement with the full-wave electromagnetic simulation results.

A DUAL-BAND BANDPASS FILTER HAVING WIDE AND NARROW BANDS SIMULTANEOUSLY USING MULTILAYERED STEPPED IMPEDANCE RESONATORS

Compact dual-band bandpass fllter (BPF) with wide and narrow bands simultaneously is presented. By using the stepped impedance resonators (SIRs) in multilayered structure, the dual-band responses with wide and narrow bands simultaneously can be obtained. The fllter has 3-dB fractional bandwidths (FBWs) of 45% and 10% for 2.4GHz and 5.2GHz, respectively. The circuit size is compact due to the multilayered structure. Moreover, multi-path propagation inside the multilayered structure generates transmission zeros at each skirt of the passbands for improving the passband selectivity. Measured results of the fllter are in good agreement with the full-wave electromagnetic (EM) simulation.

Liquid phase deposited SiO2 on GaN

Abstract An efficient and low cost approach to deposit uniform silicon dioxide layers on GaN by liquid phase deposition (LPD) near room temperature are described and discussed. The process is simple. GaN wafers are immersed into a H2SiF6 and H3BO3 solution to form the silicon dioxide layers. The deposition conditions and the properties of the SiO2 films will be characterized.

A novel triple-band bandpass filter using Multilayer-based substrates for WiMAX

A new design of triple-band bandpass filter (BPF) using multilayer-based substrates is proposed in this paper. The BPF is designed to have three passbands at 2.3-2.7 GHz, 3.3-3.9 GHz and 5.15-5.85 GHz for wireless metropolitan area network air interface (WiMAX). The design concept is to arrange three pair of coupled resonators in the multilayer structure to generate three passbands. By using the multilayer-based substrate, the triple-band BPF can simultaneously achieve size reduction and produce the cross-coupling effect. Experimental results are in good agreement with the full-wave simulation results.

New Compact Triple-Passband Bandpass Filter Using Multipath-Embedded Stepped Impedance Resonators

This letter presents a new resonator configuration to design a triple-passband filter with high passband selectivity and compact circuit size. The filter includes two multipath-embedded stepped impedance resonators (SIRs), connected with magnetically coupling by via hole technique at the symmetric plane of the filter. The multipath-embedded SIR is designed at 1.575, 2.45, and 3.5 GHz. The resonant frequencies can be easily controlled by tuning impedance ratio K i and length ratio αi (where i = 1, 2, and 3) of the multipath-embedded SIR. This study provides an effective method to easily design the triple-passband filter with compact circuit size, high passband selectivity and low insertion loss.

Characteristics of coplanar waveguide on lithium niobate crystals as a microwave substrate

A finite ground coplanar waveguide (FG-CPW) on lithium niobate (LiNbO3) substrates, without a thin SiO2 buffer layer, was experimentally characterized by using on-wafer measurements. The dielectric constant and the characteristic impedance were extracted from calibrated measurements made at up to 20GHz using the FG-CPW method. The loss tangent was then obtained by the conformal mapping approach after the dielectric constant and characteristic impedance had been accurately extracted. The dielectric losses of LiNbO3 substrates are not negligible even in the X band.