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OTA-based tunable fractional-order devices for biomedical engineering
(2021-01-01)
Prommee, Pipat
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Pienpichayapong, Peradol
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Manositthichai, Narongsak
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Wongprommoon, Natapong
This research realizes fractional-order devices or constant phase element (CPE) using continued fraction expansion (CFE) and rational function approximation methods. An RC ladder network prototype was realized using CFE based on the Cauer network principle. The RC ladder network and signal flow graph (SFG) were employed to realize the proposed CPE. Voltage gain circuits and voltage-mode integrators were realized by using operational transconductance amplifiers (OTA) and grounded capacitors. The proposed CPE was subsequently synthesized using voltage gain circuits and voltage-mode integrators based on SFG. The proposed CPE could function as fractional-order capacitor and fractional-order inductor. Besides, the CPE could be constructed in arbitrary fractional-orders. The impedance and operation frequency are independently tunable by manipulating OTA bias current. To validate, the proposed fractional-order device was applied to six types of electrical Cole models of skull tissues, and simulation results were compared with the approximation function and theory. The electrical characteristics of the Cole models based on the proposed CPE are comparable to the theoretical characteristics of the Cole model.
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Realization of Tunable Fractional-order Device based on Ladder Network Approximation
(2020-06-01)
Prommee, Pipat
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Pienpichayapong, Peradol
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Manositthichai, Narongsak
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Wongprommoon, Natapong
This paper describes a design and realization of a fractional-order device or constant phase element (CPE) using the approximation method. The rational function is applied for the fractional-order function. The rational function can be rewritten in the continue fraction expansions (CFE) form. The Cauer network type is realized from the CFE as RC ladder network. The signal flow graph (SFG) method is preferred to realize the active network from the passive RC ladder network. The finalized CPE requires the gains and integrators in voltage-mode. The OTAs are deployed as tunable active devices with grounded capacitors to realize the tunable fractional-order device. From the design procedure, the proposed CPE can be constructed in arbitrarily order and frequency operation. Moreover, the tunable of magnitude and frequency operation can be electronically tuned. The good agreement results of proposed CPE are carried out by PSpice compared to the theoretical expectation.
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Simple structure OTA-C elliptic band-pass filter
(2019-07-01)
Prommee, Pipat
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Wongprommoon, Natapong
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Khateb, Fabian
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Manositthichai, Narongsak
This paper presents a new Elliptic ladder bandpass (BP) filter based on MO-OTA. This RLC ladder low-pass (LP) prototype and network transformation are used to create the band-pass signal flow graph (SFG). From SFG, the integrators and differentiator are required to realize the BP Elliptic filter with low-complexity configuration. The integrator and differentiator circuits can generally be obtained based on OTA-C technique. Lossy and lossless integrators and differentiators based on MO-OTA(s) are straight-forward applied to SFG for achieving the designed filter. Based on this technique, the circuit is obviously apparent that the final circuit has low-complexity and low-component count compared with the conventional technique. This proposed BP Elliptic filter contains only 10 bipolar MO-OTAs and 8 grounded capacitors. The frequency responses can be tuned between 2kHz and 100kHz through the bias currents of OTA. The simulation results are carried out by PSpice and agreed well with theory anticipation.
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OTA-C based compact Low-pass Elliptic Filter
(2018-12-24)
Wongprommoon, Natapong
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Manositthichai, Narongsak
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Prommee, Pipat
This article described a compact structure simulating electronically controlled high-order Elliptic filter based on OTA-C. The signal flow graph (SFG) is deployed as a synthesis method from RLC prototype. The synthesis of Elliptic filter using SFG is normally required the integrators and very low current/voltage gain. This proposed filter is synthesized by using SFG and no required any current/voltage gains. From its SFG, the OTA-C based integrators and differentiators can be realized. The completed circuit is using only grounded capacitors with low-complexity structure. The frequency response of proposed filter can be tuned through the equality of OTA's bias currents. The supply voltage is using ±. The comparison of proposed filter and RLC prototype characteristics are verified by PSpice that the results are in good agreement.
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Integrable QPSK Modulator Using CMOS Technology
(2018-08-20)
Wongprommoon, Natapong
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Manositthichai, Narongsak
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Prommee, Pipat
This paper presents a design of voltage-mode QPSK modulator circuit based on CMOS analog signal processing subsystems. The circuit consists of dual-output all-pass filter, analog switches and summing operator. All-pass filter is used as a phase-shifter which provides ± 90 degrees phase shifted at considered frequency. Trigonometric relationship identities are used for obtaining the completed 4-quadrant phase shifted signals. CMOS analog switches are constructed with the summing junction for obtaining the QPSK modulation signal outputs by arithmetic algorithm. All-pass filter and summing junction are realized by using CMOS-based differential voltage buffer (DVB) with a few passive elements. The results are verified by PSpice using ± 1.5V power supplies which are in agreement with the theory expectations.
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High-order bp filter using biquad log-domain method
(2018-07-02)
Wongprommoon, Natapong
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Manositthichai, Narongsak
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Prommee, Pipat
High-order band-pass ladder filter based on Log-domain biquad functions is presented in this paper. High-order ladder filter is designed from RLC ladder filter prototype based on two types of biquad log-domain filters. Log-domain lossy and lossless integrator concepts are used to realize biquad log-domain filter in each type. Log-domain lossy integrator is easily realized by using 7 transistors and 1 grounded capacitor and log-domain lossless integrator is also easily realized by using log-domain lossy integrator by adding feedback to the input which consists of 8 transistors and 1 grounded capacitor. By adjusting bias current the frequency responses the filter can be obtain between 100 kHz and 100 MHz. This filter operates in transistor level which is suitable for operating in high frequency operation. A commercial array BJT technology is used in PSpice simulation.
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Active-only variable-gain low-pass filter for dual-mode multiphase sinusoidal oscillator application
(2017-01-01)
Prommee, Pipat
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Manositthichai, Narongsak
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Khateb, Fabian
This research presents an active-only low-pass (LP) filter whose pole frequency and gain are independently tunable by means of bias current manipulation. The realization of the proposed LP filter required one operational amplifier, two operational transconductance amplifiers, and two MOS transistors. The multiphase sinusoidal oscillator (MSO) was subsequently realized by cascading n LP filters (n = 3) and loop-backing the output of the last LP filter to the input of the first LP filter. Simulations were carried out and the results revealed that the MSO could simultaneously achieve low impedance voltage and high impedance current outputs without the circuit topology alteration. The frequency of oscillation and the condition of oscillation could also be electronically tuned without disturbing each other. Furthermore, the sinusoidal signal of the MSO exhibited relatively low total harmonic distortion of about 0.8% at 2.75 MHz. To verify, a prototype of the active-only LP-based MSO (n = 3) was constructed and experiments were performed. The experimental findings were agreeable with the simulation results.
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The statistics of equatorial spread-F at the conjugate stations in Southeast Asia
(2014-01-01)
Klinngam, Somjai
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Supnithi, Pornchai
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Manositthichai, Narongsak
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Sepsirisuk, Kasemsuk
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Tsugawa, Takuya
Ionospheric disturbance is a major impediment to current communication systems with the signals propagating through the ionosphere. A signature of such disturbance when appearing in an ionogram, resulting from the ionosonde observation system, is known as spread-F. The spread-F statistics is therefore crucial to the design and operation of communication system. In this work, we analyze the equatorial spread-F (ESF) statistics at the conjugate stations: Chiangmai, Chumphon and Kototabang during the period of minimum solar activity from September 2008 to April 2009. The statistics of range type spread-F (RSF) occurrence after the local sunset are shown in terms of the monthly average percentage since it is related to the Equatorial Plasma Bubble (ESP). We found that the RSF occurrence is higher at Chumphon station, which is near the magnetic equator, than at Kototabang and Chiangmai stations. The maximum level occurs during March 2009 at Chumphon station and the higher rate mostly during the equinoctial months. In addition, we compare the observed RSF occurrence probability at Chumphon station with the IRI-2012 model prediction. The comparison results show that the IRI model overestimates our results in all seasons, most evidently in December Solstice, except the estimation in June solstice during 21:00-03:30 LT when IRI model underestimates the statistics of RSF occurrence. Nevertheless, the IRI model gives closer probability values in March equinox during 20:00-22:00 LT than other seasons. © 2014 IEEE.
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Experimental characterization of a UWB channel model for body area networks
(2011-12-01)
Arpasin, Dissakan
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Manositthichai, Narongsak
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Promwong, Sathaporn
Wireless technology today are more advancement, especially technique use in communication and communication devices are likely to be closer on the more human. This research is impact of UWB Impulse radio with human body base on measurement data, this type of technology is a high-speed data transmission. To study the impact of the human body that affect the technology UWB, Using a vector network analyzer (VNA) measure and record the result. Finally, Is determined by the parameter such as path loss, power delay profile and study parameters until the model is designed to measure and test it on human body in indoor environment with using the broadband antenna in testing. This research is useful research and basic research for the network to build on the human body with high speed UWB technology in the future. © 2011 IEEE.
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Antenna transfer function evaluation scheme for ultra wideband medical applications
(2011-12-01)
Koonchiang, Krisada
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Manositthichai, Narongsak
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Fongsamut, Chalermpan
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Promwong, Sathaporn
Antennas which are used to transmit and receive UWB signals must be able to accomodate its large bandwidth. Moreover, the signals should not be distorted too much when they pass through the antennas. Therefore, the transfer function of antennas should be known for the performance evaluation. Conventionally, the authors measure the transfer function of the antenna by measuring the transmission coefficient between the transmit and the receive antenna, assuming that the transmit and receive antennas are identical. In this presentation, a more accurate three-antenna method is introduced so that the transfer function of each individual antenna can be measured. By using this method, biconical antennas are tested. The results show that these transfer functions are close to each other and that the antenna can be used for UWB meadical application (UWB-MA). Friis' transmission formula in complex form to treat the UWB signals to take into account the waveform distortion due to the frequency characteristics of the antennas [1], [7]. It is noted that Friis' transmission formula is applicable only in the far field region. In wireless meadical environments, however, the distance may not satisfy the far field condition. In this paper, we discusses the antenna evaluation of the transmission properties in Fresnel region. © 2011 IEEE.

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