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1.
Vinylogous Dieckmann condensations equivalent to enolexo-exo-trig and enolendo-exo-trig cyclisations have been investigated. Five membered rings were smoothly obtained from the former whereas the latter cyclisations occurred with six but not with five membered ring systems. 相似文献
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Chutima Phechkrajang Putthiporn Khongkaew Waree Limwikrant Montree Jaturanpinyo 《Molecules (Basel, Switzerland)》2022,27(12)
Non-destructive analysis of chlorpheniramine maleate (CPM), pharmaceutical tablets, and granules was conducted by chemometrics-assisted attenuated total reflectance infrared spectroscopy (ATR-IR). For tablets, an optimum PLSR model with eight latent factors was obtained from area-normalized and standard normal variate (SNV) pretreated ATR-IR spectral data with correlation coefficients (R2) of calibration and cross-validation of 0.9716 and 0.9602, respectively. The model capability for the 42 test set samples was proven with R2 between the reference and model prediction values of 0.9632, and a root-mean-square error of prediction (RMSEP) of 1.7786. The successive PLSR model for granules was constructed from SNV and first derivative pretreated ATR-IR spectral data with two latent factors and correlation coefficients (R2) of calibration and cross-validation of 0.9577 and 0.9450, respectively. 相似文献
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Montree Kumngern Boonying KnobnobAuthor VitaeKobchai DejhanAuthor Vitae 《AEUE-International Journal of Electronics and Communications》2010,64(10):934-939
This paper describes a new electronically tunable three inputs and single output voltage-mode universal biquadratic filter based on simple CMOS operational transconductance amplifiers (OTAs) and grounded capacitors. The proposed configuration provides lowpass, highpass, bandpass, bandstop and allpass voltage responses at a high impedance input terminal, which enable easy cascadability. Additionally, the circuit parameters ωo and Q can be set orthogonally by adjusting the transconductances and grounded capacitors. The filter also offers an independent electronic control of parameters ωo by adjusting the transconductance through the bias current/voltage of the OTA. For realizing all the filter responses, no critical component matching condition is required, and all the incremental parameter sensitivities are low. PSPICE simulation results are performed to confirm the theoretical analysis. 相似文献
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Fabian Khateb Montree Kumngern Tomasz Kulej 《Circuits, Systems, and Signal Processing》2016,35(5):1507-1529
A new solution for a non-conventional loser-take-all (LTA) circuit is proposed in the paper. The circuit possesses several inverting and non-inverting input terminals and an additional current output, which increases its versatility and allows simplifying its possible applications. In order to show its usefulness and versatility, several new applications of the proposed LTA have also been developed, including a simple digital-to-analog converter, an n-bit programmable adder/summer, a chopper modulator and a precision rectifier. The LTA has been designed and fabricated with a 0.35 \(\upmu \hbox {m}\) CMOS I3T25 AMIS process, exploiting the recently proposed bulk-driven quasi-floating-gate technique. The LTA circuit operates from 1 V supply and dissipates 74 \(\upmu \hbox {W}\) of power. The simulations performed in Cadence environment and the measurements of a real chip confirm the attractive features of the proposed LTA. 相似文献
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Electronically tunable voltage-mode universal filter with single-input five-output using simple OTAs
Montree Kumngern Peerawut Suwanjan Kobchai Dejhan 《International Journal of Electronics》2013,100(8):1118-1133
This article presents a new electronically tunable voltage-mode universal biquadratic filter with single-input five-output using simple operational transconductance amplifiers (OTAs) and grounded capacitors. The proposed configuration provides low-pass, band-pass, high-pass, band-stop and all-pass voltage responses at a high-impedance input terminal that enables easy cascading in voltage-mode. The natural frequency and the quality factor can be set orthogonally by adjusting the circuit components. The natural frequency can also be controlled electronically by adjusting the bias currents of the OTAs. For realising all the five standard filtering functions, no critical-matching conditions are imposed and all the incremental parameter sensitivities are low. Experimental and simulation results that confirm the theoretical predictions are given. 相似文献
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Enhancing the performances of analog circuits with sub-volt supplies becomes a great challenge for circuit designers. Techniques such as bulk-driven (BD) and quasi-floating gate (QFG) count among the suitable ones for ultra-low voltage (ULV) operation capability with extended input voltage range and simple CMOS circuitry. However, in comparison to the conventional gate-driven (GD) MOS transistor (MOST), these techniques suffer from several disadvantages such as low transconductance value and bandwidth that limit their applicability for some applications. Therefore, the idea of merging the BD and QFG techniques to eliminate their drawbacks appears as efficacious solution. This new merging is named bulk-driven quasi-floating gate (BD-QFG)* technique and in order to demonstrate its advantages in compassion to BD and QFG ones, this paper presents a comparison study of three ULV differential difference current conveyor (DDCC) blocks based on BD, QFG and BD-QFG techniques. The significant increment of the transconductance and the bandwidth values of the BD-QFG are clearly observed. The proposed CMOS structures of the DDCCs work at ±300 mV supply voltage and 18.5 µW power consumption. The simulation results using 0.18 µm CMOS n-Well process from TSMC show the features of the proposed circuits. 相似文献
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A novel simple current-mode analog multiplier/divider, based on current-controlled current-differencing transconductance amplifier (CCCDTA), is presented. The proposed circuit employs only single CCCDTA without any external passive element requirement and it can work as multiplier and divider without changing its topology. In addition, the proposed circuit can work as gain-controllable current amplifier. The circuit performances are depicted through PSPICE simulations. The simulated results show that: for power supply, the total harmonic distortion is about 0.1%, the bandwidth is more than 26.94 MHz, maximum input range is about and the output current is low sensitive to temperature variations. 相似文献
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This article introduces a circuit which can function both as a quadrature oscillator and as a universal biquad filter (lowpass,
highpass, bandpass). When the circuit functions as a universal biquad filter, the quality factor and pole frequency can be
tuned orthogonally via the input bias currents. When it functions as a quadrature oscillator, the oscillation condition and
oscillation frequency can be adjusted independently by the input bias currents. The proposed circuit can work as either a
quadrature oscillator or a biquad filter without changing the circuit topology. The amplitude of the proposed oscillator can
be independently controlled via the input bias currents. The proposed oscillator can be applied to provide amplitude modulated/amplitude
shift keyed signals with the above-mentioned major advantages. The circuit is very simple, consisting of four dual-output
second generation current controlled current conveyors (DO-CCCIIs), one operational transconductance amplifier (OTA), and
two grounded capacitors. Without any external resistors and using only grounded elements, this circuit is therefore suitable
for IC architecture. PSPICE simulation results are depicted here, and the given results agree well with the theoretical analysis.
The power consumption is approximately 7.32 mW at ±2.5 V supply voltages. 相似文献