Tuntrakool, Sunti

Preferred name

Tuntrakool, Sunti

Alternative Name

Tuntrakool, S.

Main Affiliation

School of Industrial Education and Technology

sunti.tu@kmitl.ac.th

Now showing 1 - 10 of 18

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Quadrature oscillator with independent frequency control using ECCIIs
(2015-01-26)
Kumngern, Montree
;
Tuntrakool, Sunti
This paper presents a new mixed-mode quadrature oscillator. The proposed structure employs two electronically tunable second-generation current conveyors, two grounded capacitors and three grounded resistors which is suitable for integrated circuit implementation. Unlike previously oscillators, both the condition of oscillation and the frequency of oscillation of the proposed oscillator can be controlled using resistors and/or current-gain of ECCII. The circuit provides two quadrature current outputs and two quadrature voltage outputs. The current output terminals also possess high-impedance level which can be directly connected to the next stage without additional buffer circuits. PSPICE simulation results are given to confirm the workability of the proposed structure.
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A new quadrature sinusoidal oscillator for telecommunication system using VDDDAs
(2016-03-22)
Chaichana, Amornchai
;
Jaikla, Winai
;
Suwanjan, Peerawut
;
Tuntrakool, Sunti
A CMOS voltage differencing differential difference amplifiers (VDDDAs) based voltage-mode quadrature sinusoidal oscillator is proposed. The proposed oscillator is based on the two integrator loop configuration with amplifier wherein the frequency of oscillation (FO) is tuned by the time constant of two integrator and the condition of oscillation (CO) is tuned by gain of amplifier. It is constructed from two VDDDAs, two resistors, and two grounded capacitors. With this structure, it is attractive to develop in monolithic chip. The tuning of frequency of oscillation can be electronically done without affecting the condition of oscillation. Also, the condition of oscillation can be adjusted by external resistor without affecting to frequency of oscillation. The simulation results have been demonstrated and discussed using parameters of 0.18um TSMC CMOS technology and +0.9V power supply voltages.
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Polarization insensitive switchable metamaterial absorber/reflector for x-band applications
(2020-01-01)
Mustapha, M. G.
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Rahim, M. K.A.
;
Murad, N. A.
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Ayop, O.
;
Tuntrakool, S.
A unit cell of squared shaped polarization-insensitive switchable metamaterial absorber/reflector is presented. The structure operates at 10.20 GHz under both absorber mode and reflector mode configurations. Copper wire bridging the gaps to form a circular shape structure were used as switches for operation mode selections. The structure was designed on an FR4 substrate, and the incidental wave angles were varied from 0 to 50 degrees. The structure demonstrated almost 100% absorption at resonance, 3.314 GHz percentage bandwidth at 80% as an absorber. On the other hand, as reflector, it demonstrated almost a 90% reflection and a usable bandwidth of 3.327 GHz.
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UWB MIMO antenna design and analysis at millimetre wave frequencies
(2025-01-01)
Mohamad Nazer, Mohamad Aiman Hadi
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Rahim, Mohamad Kamal A.
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Murad, Noor Asniza
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Samsuri, Noor Asmawati
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Pramudita, Aloysius Adya
The Ultra-Wideband (UWB) antenna is widely used in radar systems due to its wide bandwidth and high diversity gain. However, UWB systems also experience challenges related to multipath fading. To address these issues, multiple-input-multiple-output (MIMO) technology has been introduced. To improve the performance of MIMO systems, it is essential for the elements within the MIMO antenna array to exhibit low correlation and high total efficiency. In this paper a design and simulation of a printed UWB antenna with additional MIMO implementation. The simulation results from three different MIMO configurations were systematically compared to assess their performance based on three parameters of MIMO: the Envelope Correlation Coefficient (ECC), Diversity Gain (DG), and Mean Effective Gain (MEG). In this proposal of the project, the evaluation of results is primarily cantered around the design of UWB antenna and analysis of the MIMO configurations.
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Broadband Reflective Metasurface at X-band Frequency Using Snowflakes Fractal Ring Design
(2025-01-01)
Yaziz, Nur Syahirah Mohd
;
Rahim, Mohamad Kamal A.
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Samsuri, Noor Asmawati
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Zubir, Farid
;
Tuntrakool, Sunti
A broadband reflective metasurface has been designed to integrate inward and outward fractal Koch rings operating at X-band frequencies. The integration between the inward and outward fractal Koch ring creates the snowflake fractal shape that operates at a center frequency of 10 GHz. Based on the simulated results, the reflection values are 0.9 with the reflection phase of 1800 which is between 900 to -900. Overall, all resonance frequencies exhibit more than 90% reflected power, with bandwidth of 1.90 GHz that cover from 8.70 GHz to 10.60 GHz.
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Temperature Insensitive Current-Mode Four Quadrant Multiplier Using Single CFCTA
(2017-02-09)
Tuntrakool, Sunti
;
Suwanjan, Peerawut
;
Jaikla, Winai
A four quadrant multiplier of two current input signals using active building block, namely current follower cascaded transconductance amplifier (CFCTA) is presented in this paper. The proposed multiplier consists of only single CFCTA without the use of any passive element. The presented circuit has low impedance at current input node and high impedance at current output node which is convenient for cascading in current mode circuit without the need of current buffer circuits. The output current can multiply two input currents with temperature insensitivity. Moreover, the magnitude of output current can be controlled electronically via DC bias current. With only single active building block, the presented multiplier is suitable for integrated circuit implementation for analog signal processing. Simulation results from a PSpice program are presented in order to demonstrate the multiplier proposed here.
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Dual-Band Reflective Metasurfaces for 5G mmWave Applications: Design, Analysis, and Waveguide Validations
(2026-01-01)
Mohammed, Sunusi Garba
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Samsuri, Noor Asmawati Binti
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Rahim, Mohamad Kamal B.A.
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Ripin, Nabilah Binti
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Taufiqqurrachman
This paper presents a dual-band reflective metasurface unit cell for millimeter-wave RIS applications operating at 26 GHz and 28 GHz, covering the 5G n258 and n257 bands. The proposed design features a hybrid resonator structure to achieve a consistent phase trend and strong reflection performance across the 5G mmWave frequency band. To ensure stable dual-band performance of the unit cell, parametric optimization is conducted. The unit cell is investigated through Floquet simulations and WR-34 rectangular -to-square waveguide-transition-based full-wave simulations, followed by experimental validation using a fabricated WR-34 rectangular-to-square waveguide transition. The simulated resonances at 26 GHz and 28 GHz are experimentally observed at 26.7 GHz and 28.9 GHz, respectively, indicating minor frequency deviations. Measured results demonstrate reflection magnitudes of -1.80 dB at 26.7 GHz and -0.80 dB at 28.9 GHz, with corresponding phase responses of - 68° and -13°, and bandwidths of 5.12% and 6.07%, respectively.
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Geometry-Driven Performance of Unit Cells in Multiband Reflective Metasurfaces: A Comparative Study
(2025-01-01)
Taufiqqurrachman
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Rahim, Mohamad Kamal B.A.
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Samsuri, Noor Asmawati Binti
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Wijayanto, Yusuf Nur
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Yaziz, Nur Syahirah Mohd
A multiband reflective metasurface can be designed using a multi-ring resonator, where the resonator can take various shapes such as circular, square, hexagonal, triangular, and others. This paper presents a comparative study of unit-cell multiband reflective metasurfaces based on their geometric structure, focusing on reflection magnitude, reflection phase, and bandwidth performance of hexagonal and triangular shapes. Both proposed designs are designed and simulated at X-band frequencies using an F4BMX220 substrate with a thickness of 1.5 mm. Simulation results show that the hexagonal shape offers better reflection performance and a wider bandwidth compared to the triangular shape.
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Integer- And fractional-order VCO using non-inertial amplitude stabilization and modern active elements
(2020-04-28)
Sotner, Roman
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Petrzela, Jiri
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Jerabek, Jan
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Langhammer, Lukas
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Polak, Josef
This paper introduces design of the linearly tunable quadrature voltage-controlled oscillator (VCO) using modern off-the-shelf active elements suitable for the design of electronically adjustable applications. The simplified topology was achieved using non-inertial stabilization of amplitude. It allows targeting adjustability of the oscillation frequency only into lossless integrator part of the topology. This arrangement simplifies the design and the tenability also. Derived symbolical expressions indicate that gain adjustment of used amplifiers (that are still in single path) does not influence amplitude and phase shift ratio of generated waveforms, which is a beneficial feature. The performances of the circuit are tested experimentally in band of units of MHz and results confirmed expected behavior. Initial study of the oscillator with fractional-order capacitors is presented and discussed. Results are supported by laboratory measurements.
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Multiband Reflective Metasurface at X-Band Frequency Using Multi-Square Ring Resonators (SRRs)
(2025-01-01)
Taufiqqurrachman
;
Rahim, Mohamad Kamal B.A.
;
Asmawati Binti Samsuri, Noor
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Wijayanto, Yusuf Nur
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Syahirah Mohd Yaziz, Nur
A multiband reflective metasurface has been designed using a multi-Square Ring Resonator (SRR) operating at X-band frequencies. Each SRR is designed to resonate at 8, 10, and 12 GHz, respectively. Based on the simulated results, the reflection values are -0.4 dB at 8 GHz, -1.86 dB at 10 GHz, and -1.99 dB at 12 GHz, while the reflection phases are -1.06° at 8 GHz, -9.8° at 10 GHz, and -1.98° at 12 GHz. Overall, all resonance frequencies exhibit more than 60% reflected power, with bandwidths of 0.67 GHz at 8 GHz and 0.2 GHz at 10 and 12 GHz.

Tuntrakool, Sunti

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