Yeong Her Wang

A novel compact ring dual-mode filter with adjustable second-passband for dual-band applications

In this letter, a novel compact ring dual-mode with adjustable second-passband for dual-band applications are presented. A ring resonator with two different geometric dimensions are derived and designed to have identical fundamental and the first higher-order resonant frequencies, and to establish appropriate couplings in the structure. Moreover, the proposed filter has smaller size as compared with the basic topology of stopband filters and stepped-impedance-resonator (SIR) filters. The measured filter performance is in good agreement with the simulated response.

Planar Ultra-Wideband Bandpass Filter Using Edge Coupled Microstrip Lines and Stepped Impedance Open Stub

The design and implementation of a planar ultra-wideband (UWB) bandpass filter are presented. Three interdigital edge coupled microstrip lines are used for coupling enhancement. A stepped impedance open stub is used for realizing transmission zeros simultaneously in upper and lower stop bands as well as impedance matching in ultra-wide pass band. A pass band from 3.1-10.6 GHz is achieved with an insertion loss of 0.5 dB, a return loss of about 18 dB, a sharp out-of-band-rejection, and a low group delay of only 0.21ns. Single- and double-section filters are realized to meet the UWB mask requirement. The design of the filter is simple, and it shows good frequency response.

A novel cross-shape DGS applied to design ultra-wide stopband low-pass filters

This letter presents a novel low-pass filter with an ultra-wide stopband. The proposed filter is comprised of a new cross-shape defected ground structure (CSDGS). By using this structure, the filter not only supports conventional DGS performances with a sharp rejection, but also exhibits an ultra-wide stopband. For the deigned low-pass filter, an insertion loss of less than 2dB from dc to 3.5GHz and the rejection is better than 20dB from 4.3 to 15.8GHz. Predicted performances show widened and deepened stopband beyond the low passband. Furthermore, it is confirmed by measurement.

Structural and electrical characteristics of atomic layer deposited high kappa HfO2 on GaN

High κ HfO2 was deposited on n-type GaN (0001) using atomic layer deposition with Hf(NCH3C2H5)4 and H2O as the precursors. Excellent electrical properties of TiN∕HfO2∕GaN metal-oxide-semiconductor diode with the oxide thickness of 8.8nm were obtained, in terms of low electrical leakage current density (∼10−6A∕cm2 at VFB+1V), well behaved capacitance-voltage (C-V) curves having a low interfacial density of states of 2×1011cm−2eV−1 at the midgap, and a high dielectric constant of 16.5. C-V curves with clear accumulation and depletion behaviors were shown, along with negligible frequency dispersion and hysteresis with sweeping biasing voltages. The structural properties studied by high-resolution transmission electron microscopy and x-ray reflectivity show an atomically smooth oxide/GaN interface, with an interfacial layer of GaON ∼1.8nm thick, as probed using x-ray photoelectron spectroscopy.

Wilkinson Power Divider Using Microstrip EBG Cells for the Suppression of Harmonics

This letter presents a planar power divider with an effective technique for nth harmonics suppression. The proposed technique served by a microstrip electromagnetic bandgap cell is used to suppress the nth harmonics and reduce the length of a quarter-wave line over 30% as compared to the conventional divider. The planar structure enables an easy circuit design in printed circuit boards. From the measured results, a 32.5 dB suppression for the third harmonic and a 12 dB suppression for the fifth harmonic is obtained while maintaining the characteristics of a conventional Wilkinson power divider. It is able to achieve less than 3.4 0.1 dB of the two equivalent insertion losses, less than 23dB of the return loss, and better than 25dB of isolation at 2.4GHz.

CURRENT TRANSPORT MECHANISM IN TRAPPED OXIDES : A GENERALIZED TRAP-ASSISTED TUNNELING MODEL

A generalized trap-assisted tunneling (GTAT) model is proposed in this work, where an effective tunneling barrier of trapezoidal shape is considered, instead of the triangular barrier utilized in the conventional trap-assisted tunneling (TAT) model. It is demonstrated that trapezoidal barrier tunneling dominates at low electric fields (E<4 MV/cm), while triangular barrier tunneling contributes the main part of the tunneling current at high electric fields (E=6–8 MV/cm). The comparisons of this improved model and the results of the conventional TAT model at high and low electric fields are discussed. It is concluded that GTAT can more accurately model the current density-electric field (J–E) curves for the conduction enhancement of a trapped oxide film under various deposition conditions over a wider range of electric fields. This is confirmed by the comparative use of both TAT and GTAT models on experimental data obtained from existing reports. Furthermore, a simple method for determining the trap energy ...

A Fully Integrated 5 GHz Low-Voltage LNA Using Forward Body Bias Technology

A fully integrated 5 GHz low-voltage and low-power low noise amplifier (LNA) using forward body bias technology, implemented through a 0.18 mum RF CMOS technology, is demonstrated. By employing the current-reused and forward body bias technique, the proposed LNA can operate at a reduced supply voltage and power consumption. The proposed LNA delivers a power gain (S21) of 10.23 dB with a noise figure of 4.1 dB at 5 GHz, while consuming only 0.8 mW dc power with a low supply voltage of 0.6 V. The power consumption figure of merit (FOM1) and the tuning-range figure of merit (FOM2) are optimal at 12.79 dB/mW and 2.6 mW-1, respectively. The chip area is 0.89times0.89 mm2.

High-Mobility Pentacene-Based Thin-Film Transistors With a Solution-Processed Barium Titanate Insulator

Pentacene-based organic thin-film transistors (OTFTs) with solution-processed barium titanate (Ba_1.2Ti_0.8O₃) as a gate insulator are demonstrated. The electrical properties of pentacene-based TFTs show a high field-effect mobility of 8.85 cm² · V^-1 · s^-1, a low threshold voltage of -1.89 V, and a low subthreshold slope swing of 310 mV/decade. The chemical composition and binding energy of solution-processed barium titanate thin films are analyzed through X-ray photoelectron spectroscopy. The matching surface energy on the surface of the barium titanate thin film is 43.12 mJ · m^-2, which leads to Stranski-Krastanov mode growth, and thus, high mobility is exhibited in pentacene-based TFTs.

Miniature Dual-Band Filter Using Quarter Wavelength Stepped Impedance Resonators

A miniature dual-band filter using quarter wavelength (lambdag/4) stepped impedance resonators (SIRs) is proposed. Short and open SIRs are coupled together to realize lower and upper passbands, respectively. Miniaturization is achieved due to the use of lambdag/4 resonators and a combline coupling structure. Two transmission zeros in a mid-stopband and one in each lower and upper stopbands are achieved. In order to see the capability of this structure to achieve different second passband frequencies, two dual band filters at frequencies of 2.45/5.25 GHz and 2.45/5.75 GHz are realized. Measured insertion losses are 1.3 dB and 2.3 dB and return losses are better than 17 dB and 18 dB at the first and second passband frequencies, respectively, with a mid-stopband attenuation better than 30 dB. The size of the filter is as compact as 19.0 times 5.2 mm2 on a RO 4003C (epsivr = 3.38, h = 0.81 mm) substrate.

An analytic three-terminal band-to-band tunneling model on GIDL in MOSFET

An analytic three-terminal band-to-band tunneling current model for the gate-induced drain leakage current (GIDL) in an n-MOSFET is developed. This model considers impurity doping concentration, vertical field, lateral field, and so-induced electron momentum enhancement, as well as the surface electro-static potential in the gate-to-drain overlapped region. Based on a constant surface-potential approximation, a closed-form equation has been obtained instead of the complex integral-form in previous works. The results from this new model show good agreement with the measurement data over a wide range of gate and drain biases and device channel lengths. This work is useful for GIDL analysis in transistor design as well as in circuit simulation.