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A Versatile Cell of Multimode First-Order Universal Filter Using VCIIs
(2025-01-01)
Buakaew, Seangrawee
;
Silaruam, Vinai
This article presents a new generic core cell for designing the first-order universal filter employed second-generation voltage conveyor (VCII<sup>+</sup>). With appropriate admittance selection, the proposed core cell can derive four different filter types, namely, low-pass, high-pass, inverting all-pass, and noninverting all-pass functions and encompassing four basic modes: current mode (CM), voltage mode (VM), transimpedance mode (TIM), and transadmittance mode (TAM). The primary feature of the proposed filters is the ability to cascade the circuit easily, eliminating the need for an extra buffer. The proposed circuits were confirmed by 0.18-μm TSMC CMOS process technology simulations. Numerous simulation results are included to verify the validity of the proposed circuits. Moreover, the experimental results of some proposed circuits from the commercial device built around AD844 agree well with the theory.
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Porous Silicon Formation by Stain Etching on Pyramid Surface in U-Shape MSM Photodetector
(2024-01-01)
Muanghlua, Rangson
;
Atiwongsangthong, Narin
;
Vijafun, Jidapa
;
Suttijalern, Kamonwan
;
Niemcharoen, Surasak
In this paper, the porous silicon formation on pyramid surface in U-shape MSM photodetector was studied. Stain etching technique was used to prepare porous silicon material. The solution for stain etching contained the mixed solution of hydrofluoric acid (HF), nitric acid (HNO<inf>3</inf>) and deionized water (DI) with ratios 1: 3: 5 and used halogen lamp expouse 30,000 lux between etching for excite porous formation in 2 minutes. Porous silicon was fabricated on pyramid surface in U shape which between metal electrode titanium and aluminum on p-type silicon 20-25 Ω-cm to reduce the reflection of incident light and to increase a photocurrent of MSM photodetector. In the final part of this paper are the comparison physical morhhology and electrical characteristic of porous silicon on pyramid surface in U shape MSM photodetector with pyramid in U-shape MSM photodetector without porous silicon on the surface and planar MSM photodetector. The physical morphology of porous silicon on pyramid surface in U-shape was studied by using scanning electron microscopy (SEM). The electrical characteristic was investigated by using incident light with wave length 635 nm and power 6 mW at bias voltage 10 V. The result of comparison, we found that porous silicon on the surface of pyramid in U-shape MSM photodetector is rougher than pyramid in U-shape MSM photodetector without porous silicon on the surface. The electrical characteristic of porous silicon on pyramid surface in U-shape MSM photodetector respond incident light higher than pyramid in U-shape MSM photodetector without porous silicon on the surface. Therefore the forming porous silicon on the suface of pyramid in U-shape MSM photodetector is appropriate for the fabrication of MSM photodetector with high photocurrent.
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Three-Phase Oscillator with Cascade Ability Using Voltage Current Conveyor
(2024-01-01)
Buakaew, Seangrawee
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Narksarp, Wipavan
;
Choeysombat, Kamonthip
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Kanjanawiwin, Juthamas
;
Atiwongsangthong, Narin
This paper presents a new circuit configuration employing voltage current conveyors (VCII) in conjunction with a minimal number of passive elements to achieve a voltage mode sinusoidal oscillator with a 3 -phase differential output. The proposed circuit features a straightforward architecture, with all passive elements connected to low-impedance nodes. Consisting solely of identical VCIIs without multiple outputs, the circuit facilitates the cascading of the 3 -phase outputs without requiring supplementary buffering. Simulation results obtained through PSPICE, along with experimental validation using commercial ICs, are provided to substantiate the efficacy of the proposed circuit.
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A miniature tunable quadrature shadow oscillator with orthogonal control
(2023-10-01)
Buakaew, Seangrawee
;
Wongtaychatham, Chariya
This article presents a new design of a quadrature shadow oscillator. The oscillator is realized using one input and two outputs of a second-order filter cell together with external amplifiers in a feedback configuration. The oscillation characteristics are controlled via the external gain without disturbing the internal filter cell, following the concept of the shadow oscillator. The proposed circuit configuration is simple with a small component-count. It consists of, two voltage-different transconductance amplifiers (VDTAs) along with a couple of passive elements. The frequency of oscillation (FO) and the condition of oscillation (CO) are controlled orthogonally via the dc bias current and external gain. Moreover, with the addition of the external gain, the frequency range of oscillation can be further extended. The proposed work is verified by computer simulation with the use of 180 nm complementary metal–oxide–semiconductor (CMOS) model parameters. The simulation gives satisfactory results of two sinusoidal output signals in quadrature with some small total harmonic distortions (THD). In addition, a circuit experiment is performed using the commercial operational transconductance amplifiers LM13700 as the active components. The circuit experiment also demonstrates satisfactory outcome which confirms the validity of the proposed circuit.
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Porous Silicon Sensing Membrane Electrode on Extended Gate Field Effect Transistor for pH Sensor
(2023-01-01)
Atiwongsangthong, Narin
;
Ausama, Atthawit
;
Buakaew, Seangrawee
In this paper, we used porous silicon as sensing membrane electrode which were formed by using anodization etching process at room temperature. Porous silicon sensing membrane electrode will be combined working with commercial N-MOSFET which used as the extended gate field effect transistor (PS-EGFET) for pH sensor. P-Type silicon wafer was used as material substrate for prepare porous silicon sensing membrane electrode. Anodization parameters, the current density of 10 mA/cm2, with 48% hydrofluoric acid concentration and etching time of 10 minutes. The pH sensing of porous silicon EGFET were measured in pH value of 4, 7 and 10, respectively. From experiment, the porous silicon EGFET were exhibited high pH sensitivity on current mode in relationship between the drain current with pH value was $0.2929\ \mu\mathrm{A}^{1/2}/\text{pH}$, corresponding to the linearity of 99.72%. And, pH sensitivity on voltage mode in relationship between reference voltage with pH value was 34.8 mV/pH, corresponding to the linearity of 99.78%. The experiment results showed that the porous silicon was suitable sensing membrane material for pH sensor.
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Boosting the Quality Factor of the Shadow Bandpass Filter
(2022-09-30)
Buakaew, Seangrawee
;
Wongtaychatham, Chariya
This paper proposes a new method to increase the quality factor of the shadow bandpass filter. The proposed circuit topology is simple, with the use of conventional biquad cell along with external amplifiers. The major advantageous feature is that the quality factor of the filter is boosted up whereas the gain of the external amplifier is significantly reduced. Moreover, the presented idea can be applied to the shadow filter in both current and voltage modes. The proposed scheme is justified via circuit performance. The performance is compared with the previous research works in the same arena. The results show that a feedback signal and a properly chosen gain incredibly boost up the quality factor of the shadow bandpass filter. Simulations by PSpice using 0.18-μm CMOS-level parameters confirm the validity of the proposed work.
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Adjustable Quadrature Shadow Sinusoidal Oscillator
(2022-01-01)
Buakaew, Seangrawee
;
Atiwongsangthong, Narin
This article presents a shadow oscillator with quadrature-phase outputs. The proposed circuit employs the voltage differential transconductance amplifier (VDTA) and two grounded passive elements. The frequency of the oscillation, as well as the condition of oscillation, are accomplished through the tunning of the gains of the external amplifiers. Therefore, frequency adjustability can be performed without the effect on the biquad cell which is the main feature of the shadow oscillators. The results from the PSpice simulations employing the CMOS circuit level are included to verify the proposed quadrature shadow oscillator configurations.
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Ambient Gases Sensing by Photoluminescence Properties of Porous Silicon
(2022-01-01)
Buakaew, Seangrawee
;
Ausama, Atthawit
;
Atiwongsangthong, Narin
Ambient gas sensing was responced by photoluminescence intensity properties of porous silicon. Silicon wafer was used as starting material for porous silicon samples, anodization etching process was used to prepare porous silicon layer on p-type silicon substrate. Anodization parameters, the current etchings used between 10 to 40 mA/cm2, with 48% hydrofluoric acid concentration and etching time of 10 minutes. The porous silicon structure were described by using SEM and the porosity of samples by gravimetric technique. The samples were applied as ambient gas sensing were described by photoluminescence intensity at room temperature. The bad of photoluminescence intensity when porous silicon was stored in oxygen ambient gas and the best of photoluminescence intensity was to vacuum.
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A Simple and Compact Transimpedance Mode dc Bridge Readout
(2021-04-01)
Buakaew, Seangrawee
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Narksarp, Wipavan
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Wongtaychatham, Chariya
This paper presents a new circuit configuration of a transimpedance mode dc bridge based on an operational trans-resistance amplifier (OTRA) as an analog building block. The proposed circuit suits for small changing resistance detector. By taking the benefit of grounding property at the internal input port of the OTRA, a simple and compact dc bridge is obtained. The proposed circuit is composed of two sensing components together with a feedback resistor and only one operational trans-resistance amplifier. The circuit performances are verified by the PSPICE simulation using 0.35 m CMOS technology model parameters. The simulation results from circuit level agree well with the theoretical values.
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High Quality-Factor Shadow Bandpass Filters with Orthogonality to the Characteristic Frequency
(2020-06-01)
Buakaew, Seangrawee
;
Narksarp, Wipavan
;
Wongtaychatham, Chariya
The paper proposes the topology and implementation of the shadow bandpass filter. The main advantage of this work is that the bandpass filter possesses the distinctively high-quality factor whereas the control of this quality factor is independent with the tunability of the characteristic frequency. The circuit configuration is realized and satisfactorily verified via PSpice simulation.

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