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Voltage-Controlled Sinusoidal Oscillator Using Commercially Available ICs with Amplitude Adjustability and Its Application to FM and FSK Modulations for Transmission and Processing of Identified Low-Frequency Signals
(2026-04-01)
Suwanjan, Peerawut
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Adhan, Suchin
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Chaichana, Amornchai
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Sotner, Roman
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Nramat, Wichai
This paper presents a new voltage-controlled sinusoidal oscillator employing only two commercially available LT1228 integrated circuits, four resistors, and two capacitors. The proposed oscillator provides independent control of oscillation frequency and oscillation condition, as well as adjustable output amplitude, while maintaining low output impedance without requiring additional active components. The oscillation frequency is electronically and linearly tuned via the LT1228 bias current or control voltage. Experimental results confirm the practicality of the design: The proposed VCO achieves a wide linear tuning range from 9.25 kHz to 837.2 kHz, THD below 2.55%, and phase noise of –73.35 dBc/Hz at a 1 kHz offset for a 237.8 kHz carrier. The amplitude of the sinusoidal output is adjustable from 0.48 Vp-p to 6.64 Vp-p. In addition, the proposed VCO is successfully applied to FM and FSK modulation for low-frequency signal transmission, and the FM demodulation test yields a recovered sawtooth signal with an SNR of 34.51 dB. Compared with existing LT1228-based oscillators, the proposed circuit achieves 25% lower power consumption (149 mW) and reduces the number of ICs required while improving functional versatility. These results validate the effectiveness and novelty of the proposed LT1228-based design.
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Voltage-Mode First-order Multifunction Filter with Electronic Controllability Using VDDDA
(2025-01-01)
Chaleekrua, Nitchakan
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Siripruchyanun, Montree
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Jaikla, Winai
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Chaichana, Amornchai
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Suwanjan, Peerawut
This study presents the design of a three-input single-output voltage-mode first-order multifunction filter. The proposed filter comprises a single VDDDA as the active component, one grounded capacitor, and two resistors. The output voltage node has low impedance. The proposed filter provides three responses consisting of a low-pass (LP), a highpass (HP), and an all-pass (AP) by setting the voltage signal at the input voltage. The natural frequency (f<inf>0</inf>) and phase response are electronically controlled by the bias current (I<inf>B</inf>). This flexibility allows for precise tuning of the filter characteristics to meet specific application requirements. The passband gain of LP and HP filters can be adjusted using resistors R<inf>1</inf> and R<inf>2</inf> without affecting the f<inf>0</inf> or requiring an additional amplifier. The simulation and experimental results validate the functionality of the proposed filter as anticipated theoretically. This reliability is crucial for communications and signal processing applications, where accurate signal representation is paramount.
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A Compact Electronically Controllable Biquad Filter Synthesizing from Parallel Passive RLC Configuration
(2020-09-23)
Thinthaworn, Khanidtha
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Jaikla, Winai
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Suwanjan, Peerawut
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Adhan, Suchin
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Srichaiya, Nattapol
This paper describes a synthesis of versatile voltage-mode biquad filter. The presented multifunction filtering topology has one output node and four input nodes for applying input signal. The principle to synthesize the presented versatile second order filter is based on the parallel connection of the passive RLC circuit. The proposed filtering structure is very compact employing single active elements, voltage differencing differential difference amplifiers (VDDDA), two passive resistors and a couple of passive capacitors. In the offered circuit, five voltage-mode biquadratic filtering functions, band pass (BP), low pass (LP), high pass (HP), notch and all pass (AP) filter with unit voltage gain. These filtering functions are given by selecting the voltage signal to appropriate input voltage nodes. The tuning feature of the angular frequency (ω0) is done electronically by respective bias current. Additionally, the quality factor (Q) is tuned without affecting the ω0 by changing value of resistor. The proposed circuit is designed and supported by Pspice simulation. The implementation of VDDDA is realized from off-the-shelf available ICs, LM13700 and AD830. Several simulation results are obtained and confirmed the design and theorical analysis.
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Current/voltage controlled quadrature sinusoidal oscillators for phase sensitive detection using commercially available IC
(2020-03-01)
Jaikla, Winai
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Adhan, Suchin
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Suwanjan, Peerawut
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Kumngern, Montree
This paper presents the quadrature sinusoidal oscillators for a phase sensitive detection (PSD) system. The proposed oscillators are design by using the commercially available ICs (LT1228). The core oscillator consists of three LT1228s: two grounded capacitors and one resistor. By adding four resistors without the requirement of additional active devices, the amplitudes of two quadrature waveforms become adjustable. The quadrature output nodes are of low impedance, which can be connected to the impedance sensor or other circuits in a phase sensitive detection system without the need of buffer devices. The amplitudes of the quadrature waveform are equal during the frequency of oscillation (FO) tuning. The frequency of oscillation is electronically and linearly controlled by bias current or voltage without affecting the condition of oscillation (CO). Furthermore, the condition of oscillation is electronically controlled without affecting the frequency of oscillation. The performances of the proposed oscillators are experimentally tested with ±5 voltage power supplies. The frequency of the proposed sinusoidal oscillator can be tuned from 8.21 kHz to 1117.51 kHz. The relative frequency error is lower than 3.12% and the relative phase error is lower than 2.96%. The total harmonic distortion is lower than –38 dB (1.259%). The voltage gain of the quadrature waveforms can be tuned from 1.97 to 15.92. The measurement results demonstrate that the proposed oscillators work in a wide frequency range and it is a suitable choice for an instrument-off-the-shelf device.
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Inductance simulator with electronic controllability using single VDDDA
(2019-07-01)
Pichetpaisan, Kunakom
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Jaikla, Winai
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Siripongdee, Surapong
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Adhan, Suchin
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Silapan, Phamom
This research paper presents an active inductance simulator utilizing single voltage differencing differential difference amplifier (VDDDA), single grounded capacitor and single resistor. The control of inductance value is electronically done via adjusting bias current of VDDDA which is attractive for controlling by the microcontroller or microprocessor. To investigate the functionality of the presented active inductance simulator, the voltage-mode biquadratic band reject is designed. The theoretical behaviors of the proposed active inductor and its application are verified via Pspice simulation program and experiment using VDDDA constructed from the commercially available ICs.
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Thai sign language recognition by using geometric invariant feature and ANN classification
(2017-02-21)
Adhan, Suchin
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Pintavirooj, Chuchart
Hand sign language is the primary communication tool for people with hearing-impaired or deaf. People can use it to communicate effectively but the challenge is to communicate with the computer. Human computer interaction (HCI) will have a positive impact on their use. Thus, this is to bring the hand gestures in HCI as an important research area. This research focuses on 2D image recognition utilizing an evolved geometric invariant feature and also have developed a two-layer feedforward neural network to identify and translate hand gesture pose of the 42 letters in the Thai Sign Language (TSL) alphabet to Thai alphabets. We designed glove with six different colored markers for using in the experiment. The result shows that this system is able to recognize 42 TSL alphabets with an average accuracy of 96.19 %.
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Alphabetic hand sign interpretation using geometric invariance
(2014-01-20)
Adhan, Suchin
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Pintavirooj, Chuchart
Hand alphabet is an important sign language for disability people for a long time. This communication is also necessary for a normal people to understand the meaning as well. Hand language interpretation by applying a hand image posture classification is an active research theme to solve obstacle. In this research, we propose a promising technique to apply a B spline curvature concept for supporting a triangular-based feature extraction element in a hand interpretation process. Area, inner angle and adjacent area ratio which derived from a curvature reference set are created a feature string for each alphabet posture in the template. By testing with all 24 hand alphabets, our system provides a promising result in identification satisfactorily.
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American Sign Language recognition by using 3D geometric invariant feature and ANN classification
(2014-01-20)
Tangsuksant, Watcharin
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Adhan, Suchin
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Pintavirooj, Chuchart
Communication between normal and disabled person has been developed in several researches. The hand gesture is one of important communication for the deaf, especially American Sign Language (ASL) which is used in order to represent each alphabet (A-Z). This paper aims to translate ASL from static postures. Besides, this research also designs the glove with six different colored markers and develops algorithm for alphabet classification. Moreover the system is set by two cameras in order to extract 3D coordinate points from each marker. There are three main important processes for algorithm consisting of marker detection by using Circle Hough Transform, computation of all feasible triangle area patches constructed from 3D coordinate triplet that is novel feature, and feature classification using feedforward backpropagation of Artificial Neural Network. The experimental result shows average of accuracy is 95 percent that is high performance and feasibility for proposed method.
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3D extraction using DLT with one camera
(2013-12-01)
Adhan, Suchin
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Pintavirooj, Chuchart
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Sanpanich, Arthorn
This paper proposes a method for accurate measurement of a three-dimensional of an eye's pupil by combining local stereo images which are acquired from multiway. A calibrated mini CCD camera is used to capture the side-by-side image of one eye by two plane mirrors to create a reflection of the two directions of the eye at a time. The center of mass is used for two-dimensional coordinates of the center of the pupil. The new and simple technique to solve the problem of geometric distortion is proposed by taking advantage of the Direct Linear Transformation (DLT), which requires only a single step in the refinement stage without changing or reinstalling a camera. The DLT algorithm was used for the three-dimensional coordinates of the center of the pupils from the previous two-dimensional coordinates for the three-dimensional position of the eyes is detected. The results are the statistical errors only slight, mean = 0.16°, S.D. = 0.15°, which shows that the system is suitable for high-precision medical applications for the movement of the human eye. © 2013 IEEE.

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