Tuwanut, Panwit
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Tuwanut, Panwit
Alternative Name
Tuwanut, P.
Tuwanuti, Panwit
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Email
panwit.tu@kmitl.ac.th
9 results
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Item type:Publication, A novel versatile modulator circuit(2005-12-01); ; In this paper, a novel versatile modulator that can function either as delta modulator, sigma-delta modulator, amplitude modulator and frequency modulator is proposed. The principle of the proposed scheme is based on schmitt-trigger circuit and composed of a few components: three OTAs, one capacitor and two resistors. The advantage of this circuit is that the clock (carrier) signal employed for modulation is inherent in the circuit. The modulating signal is therefore an external input requirement. Based on the compactness of the circuit, it is suitable for IC realization. The computer simulation demonstrates the results which agree well with the theoretical analysis. © 2005 IEEE. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, A simple and economic PWM and ΣΔ modulator circuit based on modified source-couple oscillator(2006-01-01); ; In this article, a simple and economic Pulse Width Modulator (PWM) and Sigma Delta Modulator (ΣΔ) circuit which is based on the modified CMOS source couple voltage-control oscillator is presented. The circuit can work either as PWM or ΣΔ modulator, depending on the condition of the two bias currents which are forced of the source couples. Namely, the circuit is a PWM when these two bias currents are out of phase. Otherwise, it is a ΣΔ modulator when both bias currents are identical. In addition, another feature of the proposed circuit is that the modulated signal can be either in voltage or current format. Moreover, the proposed circuit provides wide range of frequency operation because of few numbers of CMOS in the circuit. Furthermore, the circuit is very suitable for realization in integrated circuits (ICs) form and can be employed for optical communication application. The simulation results of the circuit are demonstrated and agreed well with theoretical anticipation. © 2006 IEEE. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Pulse Oximetry Based on Quadrature Multiplexing of the Amplitude Modulated Photoplethysmographic Signals(2023-07-01); ; ; - Some of the metrics are blocked by yourconsent settings
Item type:Publication, A novel versatile modulator circuit(2009-05-01); ; A novel versatile modulator that can operate either as a delta modulator, a sigma-delta modulator, an amplitude modulator or a frequency modulator is presented. The proposed circuit mainly composes of a few components: which are three OTAs, one capacitor and two resistors. Among these components, two OTAs and two resistor construct a Schmitt trigger network whereas the other OTA and a capacitor compose an integrator. The advantage of this circuit is that the clock (carrier) signal employed for modulation is inherent in the circuit. No external clock is needed, only the modulating signal is required for an input. With the compactness of the circuit, it is thus suitable for IC realization. The computer simulation based on CMOS technology demonstrates that the results agree well with the theoretical analysis. © 2008 Elsevier GmbH. All rights reserved. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Time quantization derivative PWM based one-bit DPCM(2004-12-01); ; ; Koseeyaporn, P.A new 1-bit DPCM (differential pulse code modulator) circuit based on the derivative PWM (pulse width modulation) signal is proposed. The main concept of the proposed technique is that the difference of the adjacent input sample resides in the duty cycle of the derivative PWM signal. Therefore, one-bit digital signal can be exploited from the derivative PWM waveform in which the quantization process is performed in time axis, not in conventional amplitude axis. The derivative PWM principled circuit, which is composed of 3 OTAs, 1 capacitor, and 2 resistors, provides the simplicity and compactness of the circuit's structure. In addition, the sampling operation is inherent in the derivative PWM circuit thus only some additional components are required for the mentioned transformation process. Implicitly, the proposed circuit is suitable for integrated circuit fabricating technology. The PSPICE simulation outputs of the proposed technique have demonstrated the expected results. Also, SNR analysis of the quantization process will be briefly discussed. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, New analytic solution of second-order oscillator using multi-time variables technique(2005-01-01); ; In this paper, a new analysis of sinusoidal oscillator amplitude controlled by forced response using the second order differential equation (ODE) is proposed. In general, the amplitude of the complete response is derived where forced response slope is normally assumed to be zero. The value of forced response only at initial time is thus employed to determine the amplitude. But if forced input is dynamic signal the amplitude of complete response gained by using such assumption is different from the experimental result. Thus, a new analysis of amplitude for a dynamic forced response is proposed in this paper. It is found that the forced response at any arbitrary time (not only at the initial time) is presented in a term of natural response magnitude. Magnitude of natural response is therefore directly controlled by forced response. To confirm the theoretical analysis, experimental results have been demonstrated and agreed well with the analysis results. © 2005 IEEE. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Simplified Derivative-Based Carrierless PPM Using VCO and Monostable Multivibrator(2025-06-01); ; ; - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Influence of Light Intensity on a Motion Artifact Signal in a Photoplethysmographic Signal(2018-11-27); ; A photoplethygraphic (PPG) signal acquired from a commercial pulse oximeter is habitually disfigured by a motion artifact (MA) signal while any motion takes place. Inherently, the MA signal can either be additive or multiplicative, By having the MA signal intertwined with the PPG signal, the estimate of the oxygen saturation (SpO2) value is unreliable. The computation of SO02 value is based on proper red and infrared (IR) PPG signals measured by the pulse oximeter. Generally, the frequency components of the red and IR PPG signals as well as the MA signal are in the same range. To overwhelm this problem, the frequency components of the red and IR PPG signals are severed from the frequency band of the MA signal. To implement the separation, a legacy source of driving red and IR LEDs in the pulse oximeter is replaced by two alternating current sources having different frequencies. With this solution, the additive MA signal is no longer involved but the multiplicative MA signal is yet not concluded. In this work, change in light intensity fed to both red and IR LEDs is studied whether the changed light intensity has any impact on the multiplicative MA signal. According to the study, it is found that change in light intensity does not affect the multiplicative MA signal. The multiplicative MA signal still exists since the overall calculated SpO2 values have some error up to 1 %. Besides, change in light intensity does not improve the quality of the estimated SpO2 values while resting. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, A novel monostable multivibrator circuit(2005-01-01); ; This article represents a novel monostable multivibrator circuit in which width and height of the pulse output can be independent electronically adjusted. In addition, the pulse width of output is not restricted to be wider or narrower than that of input pulse as conventionally employed. Namely, there is no restriction on the width of input and output pulse, the circuit's implementation is thus more convenient. The proposed circuit is composed of three OTAs, two resistors and one capacitor, basically constructed a simple pulse generator (Schmitt-trigger circuit). Therewith the compactness of the circuit, It Is thus suitable to be fabricated for integrated circuit. The results of circuit simulation is accordance well with theoretical analysis.