Muammar Mohamad Isa
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Preferred name
Muammar Mohamad Isa
Official Name
Muammar , Mohamad Isa
Alternative Name
Isa, M. M.
Mohamad Isa, M.
Isa, Muammar Mohamad
Mohamad Isa, Muammar
Isa, M. Mohamad
Main Affiliation
Scopus Author ID
57202563525
Researcher ID
N-2105-2017

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Remazol orange dye sensitized solar cell

2017-01-03 , Siti Salwa Mat Isa , Muhammad Mahyiddin Ramli , Nor Azura Malini Ahmad Hambali , Muda M.R. , Shahrir Rizal Kasjoo , Muammar Mohamad Isa , Nurul Izza Mohd Nor , Norhawati Ahmad , Nazuhusna Khalid , Nur M. Selamat , Nur Asyikin Mohd Anhar

Water based Remazol Orange was utilized as the dye sensitizer for dye sensitized solar cell. The annealing temperature of TiO2 working electrode was set at 450 °C. The performance of the device was investigated between dye concentrations of 0.25 mM and 2.5 mM at three different immersion times (3, 12 and 24 hours). The adsorption peak of the dye sensitizer was evaluated using UV-Vis-Nir and the device performance was tested using solar cell simulator. The results show that the performance was increased at higher dye concentration and longer immersion time. The best device performance was obtained at 0.2% for dye concentration of 2.5 mM immersed at 24 hours.

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Linear modelling of novel InGaAs/InAlAs/InP pHEMT for low noise applications

2017-01-03 , En A.Y. , Norhawati Ahmad , Muammar Mohamad Isa , Siti Salwa Mat Siti , Muhammad Mahyiddin Ramli , Nazuhusna Khalid , Nurul Izza Mohd Nor , Shahrir Rizal Kasjoo , Missous M.

Linear modelling of novel InGaAs/InAlAs/InP pHEMT for low noise applications is substantial to the future transistors that will operate in high speed and low noise conditions. The novel pHEMT is constructed by sandwiching two different materials together with different lattice constants, for instance InGaAs and InAlAs in order to form a heterojunction in between. However, InP is only utilised to be the substrate base of pHEMT. In the modelling process, extrinsic and intrinsic parameters need to be extracted. Briefly, a high accuracy transistor modelling enables designers to predict the real output of a circuit before it can be fabricated onto an actual chip.

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Non-linear analysis of Self-Switching Diodes as microwave rectifiers

2017-01-01 , Shahrir Rizal Kasjoo , Zulfadhli Zailan , Sanna Taking , Wan Zuki Azman Wan Muhamad , Muammar Mohamad Isa , Arshad M.

A planar device known as the Self-Switching Diode (SSD) has been demonstrated as a high-speed rectifier, up to terahertz frequencies. The rectifying properties of SSD are dependent on a nonlinear current-voltage characteristic of the device. In this research, the rectification of two SSD rectifiers has been reported and their performances were evaluated. The observed results showed a good agreement with the nonlinear theoretical analysis of both rectifiers by means of a Taylor series which can be utilized in improving the rectifying performance of any diode-based rectifier specifically for diodes with tunable threshold voltage such as SSDs.

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Compact broadband triple-ring five-port reflectometer for microwave brain imaging applications

2019-01-01 , Hossain T.M. , Jamlos M.F. , Mohd Aminudin Jamlos , Soh Ping Jack , Ibrahim S.Z. , Muammar Mohamad Isa , Schreurs D.M.M.P. , Narbudowicz A. , Mohd Fathullah Ghazli@Ghazali

The broadband five-port reflectometer (FPR) is proposed using a triple-ring based technique. The design introduces a tapering in the inter-ring transmission lines (TLs), which provides additional degrees of freedom for optimization and contributes to increased bandwidth. The miniaturization strategy allows incorporating the third ring without significant size increase. In addition, a method for expressing the effective physical dimension of a planar symmetric FPR is also presented in an easily comprehensible way, which can be implemented for other symmetric planar junctions with more than four ports. The proposed design comprises three concentric rings with phase-shifting arrangements between the inter-ring TLs and outer matching arm sections. Inter-ring TLs are shifted by 36° (half factorized value of the inter-port angular distance of 72°) in three different optimizing steps. Tapered TLs have been used between two consecutive rings to achieve very wide bandwidth of at least 88% in simulations and at least 85% in measurements. Curved matching TLs are used in the final design, yielding a compact size of 0.397λg × 0.377 λg with 43% reduction in length and 43% in width compared to its non-compact counterpart. Genetic algorithm and quasi-Newton algorithm are used in optimizing the final prototype for operation in the frequency band used for brain microwave imaging. The proposed FPR realized a fractional bandwidth of at least 85% (from 0.96 to 2.38 GHz) with a reflection coefficient below-20 dB and a-6 ± 1 dB transmission coefficient with the required phase shift of ±120° between different ports. The measured results agree well with the simulation. Finally, the overall imaging system setup and image construction algorithm are presented and discussed for possible incorporation with this FPR for brain microwave imaging.

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Application of Taguchi method in optimization of structural parameters in self-switching diode to improve the rectification performance

2020-01-08 , Nor Farhani Zakaria , Shahrir Rizal Kasjoo , Muammar Mohamad Isa , Zarimawaty Zailan , Mokhar M.B.M. , Juhari N.

This paper presents the use of Taguchi method in the optimization process of a Self-switching Diode (SSD) as a Terahertz rectifier to obtain the optimal parameters for rectification. The rectification performance is mainly contributed by a parameter known as curvature coefficient, γ which is derived from the current-voltage (I-V) behavior of the device and can be altered by varying the device's geometrical structure. The parameters involved are the channel length, channel width and trenches width of the device, and the rectification performance are observed based on the peak of γand its corresponding bias voltage. Using Taguchi method for design of experiment (DOE), effects on the interaction among these parameters are investigated by employing the orthogonal array and evaluation of the signal-to-noise (S/N) ratio both in the peak of γand its corresponding bias voltage. The proposed parameters using this method showed γ peak of 32 V-1 and 30 V-1 at DC bias of 30 mV and zero-bias, respectively.

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Low voltage low power FGMOS based current mirror

2017-11-22 , Nurulain D. , Musa F.A.S. , Muammar Mohamad Isa , Norhawati Ahmad , Shahrir Rizal Kasjoo

This paper presents the comparison of a conventional current mirror with the one utilizing floating gate MOSFET transistors (FGMOS) to achieve low power (LP) and low voltage (LV) design. The device structure has been simulated with 0.1μ CMOS technology and 1.2V voltage supply by using SAED 90nm PDK with the Synopsys Custom Designer tool. The FGMOS circuit has shown to have low power consumption of 9.62mW, smaller threshold voltage of 0.2V and Iout of 20 mA. The improvement of 40.1% from conventional current mirror has shown the LV and LP capability of FGMOS transistor.

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Gain enhancement of microstrip patch antenna using artificial magnetic conductor

2019-03-01 , Norfatihah Bahari , Jamlos M.F. , Muammar Mohamad Isa

The paper presents an artificial magnetic conductor (AMC) structure to enhance the gain of the double microstrip patch antenna. By placing this kind of metamaterial in between the two Rogers RT5880 substrates, the antenna achieved lots of improvement especially in terms of size miniaturization, bandwidth, return loss, gain and efficiency. The antenna is intended to operate at 16 GHz where the prospect fifth generation (5G) spectrum might be located. Integration of AMC structure into the proposed antenna helps to improve nearly 16.3% of gain and almost 23.6% of size reduction.

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Numerical Simulation and Parameters Variation of Silicon Based Self-Switching Diode (SSD) and the Effect to the Physical and Electrical Properties

2020-12-14 , Tan Y.L. , Zakaria N.F. , Shahrir Rizal Kasjoo , Safizan Shaari , Muammar Mohamad Isa , Mohd Khairuddin Md Arshad , Rahim A.F.A.

Investigation of SOI based self-switching diode (SSD) by numerical simulation for RF -DC harvesting application is presented. The rectification performance of the SSD is based on the curvature coefficient, ? and current responsivity, ß which are closely related to the I-V characteristic of a non-linear device. In this work, the structural parameters are varied to observe the electrical and physical characteristics with the aid of ATLAS Silvaco simulation tools. The rectification performance in each variation is then compared, with the highest value of ? and ß observed at 25.20 V and 12.60 V, respectively. By identifying and understanding these control factors and their effects, distinctive variations of the structural parameters by using a more deliberate optimization method can be proposed for further improvement on the rectification performance.

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Small signal modelling of novel InGaAs/InAlAs/InP pHEMT for high frequency applications

2017-01-03 , Xian O.J. , Norhawati Ahmad , Muammar Mohamad Isa , Siti Salwa Mat Isa , Muhammad Mahyiddin Ramli , Nazuhusna Khalid , Nurul Izza Mohd Nor , Shahrir Rizal Kasjoo , Missous M.

HEMT is a GaAs based field effect transistor that retains higher cutoff frequency compared to silicon based transistors. Alternatively, pHEMT enhance the performance of the HEMT in term of leakage, current conduction and the cutoff frequency of the device. The heterostructure of pHEMT improve the performance two-dimension electron gas (2DEG) in the channel layer. With these, pHEMT is believed could be perfectly used in the most of the high frequency application. In this project, small signal models of InGaAs/InAlAs/InP pHEMT with 7 extrinsic parameters and 8 intrinsic parameters are modelled.

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Silicon Self-Switching Diode (SSD) as a Full-Wave Bridge Rectifier in 5G Networks Frequencies

2022-12-01 , Yi Liang T. , Nor Farhani Zakaria , Shahrir Rizal Kasjoo , Safizan Shaari , Muammar Mohamad Isa , Mohd Khairuddin Md Arshad , Singh A.K.

The rapid growth of wireless technology has improved the network’s technology from 4G to 5G, with sub-6 GHz being the centre of attention as the primary communication spectrum band. To effectively benefit this exclusive network, the improvement in the mm-wave detection of this range is crucial. In this work, a silicon self-switching device (SSD) based full-wave bridge rectifier was proposed as a candidate for a usable RF-DC converter in this frequency range. SSD has a similar operation to a conventional pn junction diode, but with advantages in fabrication simplicity where it does not require doping and junctions. The optimized structure of the SSD was cascaded and arranged to create a functional full-wave bridge rectifier with a quadratic relationship between the input voltage and outputs current. AC transient analysis and theoretical calculation performed on the full-wave rectifier shows an estimated cut-off frequency at ~12 GHz, with calculated responsivity and noise equivalent power of 1956.72 V/W and 2.3753 pW/Hz1/2, respectively. These results show the capability of silicon SSD to function as a full-wave bridge rectifier and is a potential candidate for RF-DC conversion in the targeted 5G frequency band and can be exploited for future energy harvesting application.

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