Tuwanut, Panwit
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Tuwanut, Panwit
Alternative Name
Tuwanut, P.
Tuwanuti, Panwit
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Email
panwit.tu@kmitl.ac.th
16 results
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Item type:Publication, Phase noise phenomenon explanation based multi-time variables differential equation technique(2016-09-06); In this article, the mathematical analysis is proposed to describe phase noise phenomenon. The principle of this proposed scheme is based on the multi-time variables differential equation technique. The analytic result clearly shows that noise is composed of multiplicative noise that spread around an oscillated frequency and additive noise acts as a noise floor of a system. To verify the proposed analysis, the computer simulation results are given which demonstrate that the obtained results agree well with the theoretical counterpart. - Some of the metrics are blocked by yourconsent settings
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 circuit for sigma-delta /delta modulation(2005-12-01); - 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, Triangular-to-cosine wave technique based on exponential approximation(2001-12-01); ; Maneechukate, ThongchaiA novel approach for triangular-to-cosine wave approximation is presented The cosine wave is generated by the method of squaring the triangular wave and the passing through the exponential amplifier circuits. This approach is based on the Taylor's series for sinusoidal function. The superior point of this method to the existing ones is the simple circuit realization and low distortion cosine wave output Besides that, the proposed circuit can generate the square, triangular wave. The section of square wave and triangular wave generating uses relaxation oscillator with feeding back in current mode that produce the triangular and square wave in the same circuit. Furthermore, the squaring and exponential amplifier circuit can be configured based on another principle such as translinear in current mode which can be developed to suit IC implementation. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, FM bandwidth scaling by Frequency operation under injection locked phenomena based on multi-time variable analysis(2017-05-30); This article, the FM bandwidth scaling technique under injection locked and super-harmonic injection locked phenomenon, which explained by forcing oscillation perspective with multi-time variable technique is presented. By forcing FM signal to harmonic oscillator, the FM bandwidth can be scaled. This scaling technique separated in two situations, the first one is an expansion technique under injection locked phenomenon, and the second one is a compression technique under super-harmonic injection locked phenomenon. The modified Colpitts oscillator is taken in examine, and principle verified by experimental result. - 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, New pulse oximetry detection based on the light absorbance ratio as determined from amplitude modulation indexes in the time and frequency domains(2022-05-01); ; The Pandemic COVID-19 situation, a pulse Oximetry is significant to detect a varying blood oxygen saturation of a patient who needed the device to operate with continuous, rapid, high accuracy, and immune of moving artifacts. In this article, three main schemes for low-complexity pulse oximetry detection are proposed. In the first scheme, the light absorbance ratio (R) is obtained by separating the red and infrared photoplethysmography (PPG) amplitude modulation (AM) signals from the frequency-division multiplexing (FDM) signal with two different bandpass filters (BPFs), determining the ratio of modulation index of red and infrared PPG AM signals. In the second scheme, the output PPG AM signals for the red and infrared light wavelengths from the BPFs are transformed into the frequency domain such that the AC components of both PPG AM signals are the magnitudes of the highest peaks in their respective sidebands, while the DC components are the magnitude of their carrier frequencies; then, the AC/DC ratio of the red PPG AM signal is divided by the AC/DC ratio of the infrared PPG AM signal is R. In the last scheme, the FDM signal is transformed into the frequency domain without being passed through any BPF, and R is obtained in the same way as in the same second scheme. Experimental results obtained by using the first scheme have an average error of about 0.7138%, for the second and the last scheme have an average error of about 1%, and all the methods agree with the corresponding mathematical model. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, A Practical Circuit of Cyclic Chirp Spread Spectrum Modulation for Long Range Communication(2022-01-01); ; ; Various technologies have been utilized in long range communication to satisfy increasing usage of the internet of things in a wide large area. Recently, a modulating technique called cyclic chirp spread spectrum (CSS) modulation has attracted attention due to its low power usage and long-range coverage. However, a cyclic CSS circuit is complex to build. Hence, the objective of the work is to propose a practical circuit of cyclic CSS modulation. The proposed circuit is designed to complicated-free creation. To prove that the presented circuit is pragmatic, a simulation test is performed. The simulation results have illustrated that the designed circuit well generates a chirp modulating signal. Also, the proposed circuit is flexibly configurable. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, 7 Decade low frequency switched capacitor oscillator(2001-12-01); ; Maneechukate, ThongchaiIn this work a sine wave switched-capacitor (SC) oscillator based on feedback SC BPF oscillator is proposed. Advantage of this technique is high stability, constant amplitude at wide frequency range and suitable for amplitude control by output forced response technique. In addition, frequency tuning can be adjusted by clock control, which without effect to stability. The experimental results conforming the validity of the theory are also presented.