Mohd Khairul Mohd Salleh

Achievable bandwidth of a quarter wavelength side-coupled ring resonator

Studies on the achievable range of bandwidth of a side-coupled ring resonator bandpass filter are presented. The elements of the resonator susceptible on varying the filter bandwidth are identified and design solutions are given in order to push the bandwidth to its minimum and maximum values. Based on the side-coupled ring resonator topology, two microstrip filters were designed at 10 GHz to achieve the narrowest and widest bandwidth with respect to insertion losses and technological limitation. Results of the studies with the given technology show that the ring resonator is suitable to address bandwidth from narrow (3.6%) to wide (31%). These concepts are validated through simulations and experiments for filters implemented on alumina substrate.

Quarter wavelength side-coupled ring filters for V-band applications

Designs of three bandpass filters based on quarter wavelength side-coupled ring resonator are presented for V-band applications. Centered at around 60 GHz with three different bandwidths of 2.4%, 6.2% and 11.27%, the filters are designed on a 25-mum-thick benzocyclobutene (BCB) substrate deposited on a 400-mum-thick silicon bulk. In the filter designs, three technology configurations involving multilayer microstrip and coplanar waveguide (CPW) environment are considered to achieve flexibility in coupling. Results from electromagnetic simulations of the filters are presented through this paper.

Series-cascaded ring resonators for compact microwave filter with high rejection

Very selective fifth order bandpass ring filter is presented based on two series-connected quarter-wavelength side-coupled ring resonators. As the connection between the two quarter-wavelength lines forms a half-wavelength resonator, an extra pole is produced, leading to a total of five poles since each ring resonator presents two poles. This adds to the compactness of the overall filter and improves the selectivity and rejection. Centered at 2 GHz, the filter layout is simulated and implemented on FR4 substrate using microstrips. Filter simulation and measurement results are presented to validate the idea.

Synthesis of a single side access ring resonator for higher order bandpass filters

A single-side-access ring resonator topology is presented. It employs a single quarter-wavelength coupled-line that couples to a one-wavelength ring to exhibit a single-mode resonance with transmission zeros. A global synthesis is presented, in order to control the transmission zeros in its response. As the transmission zeros of the ring resonator maintains their positions when multiple identical rings are used, the global synthesis can further be used for the design of higher order fllters with multiple rings. Furthermore, since only one coupled-line is used in the resonator topology, only one section of line is present in the ring, other than the coupled-line. Hence, there will be no second section of the ring that needs to be adjusted to obtain the symmetrical response during its realization, as compared to other types of ring topologies. To show the advantage of the synthesis, it is applied in the design of higher order ring-based bandpass fllters, which also involve extra quarter-wavelength coupled-lines to create additional poles. Five bandpass ring fllters up to 5th-order were realized using microstrip technology, and measured to validate the proposed concept. Measurement results showing good agreement with those from the simulation are also presented throughout the paper.

The designs of low power AC-DC converter for power electronics system applications

This paper reviews low power AC-DC converter in different techniques capable of developing high efficiency of energy consumption in many applications. By using low power AC-DC converter, the size of whole system integrated circuit could be reduced. However, the requirements of CMOS converter that required low input voltage and low voltage drop of MOS transistors is discussed. Different techniques in different application are implemented to overcome those problems. In this paper, the reviews of low power AC-DC converters have been focused for energy harvesting systems and wireless power devices only. These AC-DC converters consume several micro-watts from small ac or rf signal voltage and achieve excellent performance in terms of power efficiency. However, the power efficiency of AC-DC converter system is actually highly correlated to the relationship between voltage and the alternating current in ac source. It is because, an in-phase voltage and current in alternating current source is causing in good power factor performance. Power factor correction, PFC is important in many single-phase AC-DC converter circuits to reduce harmonic distortion, hence increase power efficiency of electric appliances. Therefore, the low power AC-DC converter with PFC is proposed. The post-layout of low power AC-DC converter is designed by using the Silterra 0.18 μm technology. The whole post-layout AC-DC converter circuit consumes only 50 μW and works in low voltage, 1V. The power efficiency of whole system also improved to 93%. The proposed low power AC-DC converter with PFC is suitable for future power electronics systems such as battery charger and energy conversion devices.

A design of off centered feed array (OCFA) antenna for ISM band

In this paper, a patch antenna for 2.45 GHz ISM (Industrial Scientific Medical) band Wireless Body Area Network (WBAN) applications is proposed. The antenna structure consists of a microstrip antenna array consist of 3 by 3 OCFA (off centered feed array) that is coaxial feed through type antenna with Unbalanced characteristic whereby the feed line situated off centered from the OCFA antenna structure. Two matching stub and Circular matching BalUn were introduced to match the impedance of the antenna and contribute high gain antenna about 11.84 dB at 2.45 GHz. Then, the entire proposed antennas were being analyzed in term of return loss, Voltage Standing Wave Ratio (VSWR), radiation pattern and gain. The fabricated proposed antenna only analyzed in term of return loss using Vector Network Analyzer (VNA).

Effect of swarm size parameter on Binary Particle Swarm optimization-based NARX structure selection

The NARX identification process is performed in two steps, namely model structure selection and parameter estimation. Structure selection involves selecting a subset of regressors to use that best describes the system. A Binary Particle Swarm based (BPSO) structure selected method has been implemented previously. The BPSO algorithm is subject to several parameters, namely swarm size, maximum iterations and its initial positions. This paper investigates the effect of the swarm size parameter on the convergence of the algorithm. Experiments were conducted on the DC motor dataset. The results indicate that the optimal swarm size for convergence was between 20 to 30 particles.

Wide-band microwave bandpass ring filter

This paper presents a wide-band 2nd order bandpass filter based on a dual-mode ring resonator. A slot ring is constructed in the ground plane and coupled to quarter-wavelength microstrip feedlines. This way, the coupling gap between the ring resonator and the quarter-wavelength lines can be reduced to the value of the substrate thickness. Thus, the coupling of the resonator can be improved and the bandwidth of the filter is increased. Simulation and measurement results are proposed throughout the paper to illustrate the concept and to validate the idea.

Multilayer dual-mode dual-band bandpass filter

This paper presents a single ring resonator using multilayer technique for dual-band bandpass filter. The resonator is composed of two resonators with each one having a quarter-wavelength coupled-line connected in series to a transmission line. The two resonators are arranged in parallel to form a single ring dual-band bandpass filter topology. The controlling impedance parameters of this ring are Zr for the transmission line and even- and odd-mode characteristic impedances i.e. Zoe and Zoo for the coupled-lines. Observations on the controlling parameters are conducted to investigate the effect of each parameters in terms of bandwidth, matching level and the transmission zeros. For validation, the filter is realized using multilayer technique, designed at 2 GHz on FR-4 microstrip substrate. The results exhibited good isolation between the two passbands with centered transmission zero attenuated above 40 dB while the centered frequencies were found at 1.59 GHz in the first passband and 2.41 GHz in the second passband. The simulated and measured result is presented throughout this paper to validate the concept.

Effect of different widths in CMOS rectifier for low voltage and frequency application

This paper presents the study on the effect of different widths in CMOS rectifier for low voltage and frequency application. The model is powered by 1V peak voltage of AC supply with frequency of 50Hz. This low frequency is used in this paper to match with the supply frequency from the power plant. The design is based on the CMOS 0.18um technology. The paper focuses on the effect of the two different width sizes (4um and 50um). The result for 4um is 558.36mV and increased by 40.6% for 50um width. The simulation is run using CADENCE Simulation Tools software.