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Author: search.filters.author.Dejhan, KobchaiSubject: search.filters.subject.CMOS

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    Flipped voltage follower analog nonlinear circuits
    (2012-05-01)
    Sakul, Chaiwat
    ;
    Dejhan, Kobchai
    This paper describes squaring and square-rooting circuits operable on low voltage supplies, with their application proposed hereby as vector-summation and four-quadrant multiplier circuits. These circuits make use of a flipped voltage follower (FVF) as fundamental circuit. A detail classification of basic topologies derived from the FVF is given. The proposed circuits have simple structure, wide input range and low power consumption as well as small number of devices. All circuits are also examined and supported by a set of simulations with PSpice program. The circuits can operate at power supply of ±0.7 volts, the input voltage range of the squaring circuit is ±0.8 volts with 1.59% relative error and 1.78 μW power dispersion, the input current of the square-rooting circuit is about 50 μA with 0.55% relative error and 1.4 μW power dispersion and the vector-summation circuit have linearity error of 0.23% and 2.92 μW power dispersion. As in four-quadrant multiplier circuit, the total harmonic distortion of the multiplier is less than 1.2% for 0.8 V <inf>P-P</inf> input signal at 1 MHz fundamental frequency. Experimental result is carried out to confirm the operation by using commercial CMOS transistor arrays (CD4007). These circuits are highly expected to be effective in further application of the low voltage analog signal processing. © 2012 World Scientific Publishing Company.
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    A CMOS log-antilog current multiplier/divider circuit using DDCC
    (2011-12-01)
    Torteanchai, Usa
    ;
    Kumngern, Montree
    ;
    Dejhan, Kobchai
    This paper presents a new one-quadrant analog log-antilog multiplier/divider using only one differential different current conveyor and four diodes. The proposed circuit features low circuit complexity, very suitable for integrated circuit implementation and excellent temperature stability. Simulation results show performance of the circuit and confirm the validity of the proposed design technique. © 2011 IEEE.
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    Voltage-controlled floating resistor using DDCC
    (2011-04-01)
    Kumngern, Montree
    ;
    Torteanchai, Usa
    ;
    Dejhan, Kobchai
    This paper presents a new simple configuration to realize the voltage-controlled floating resistor, which is suitable for integrated circuit implementation. The proposed resistor is composed of three main components: MOS transistor operating in the non-saturation region, DDCC, and MOS voltage divider. The MOS transistor operating in the non-saturation region is used to configure a floating linear resistor. The DDCC and the MOS transistor voltage divider are used for canceling the nonlinear component term of MOS transistor in the non-saturation region to obtain a linear current/voltage relationship. The DDCC is employed to provide a simple summer of the circuit. This circuit offers an ease for realizing the voltage divider circuit and the temperature effect that includes in term of threshold voltage can be compensated. The proposed configuration employs only 16 MOS transistors. The performances of the proposed circuit are simulated with PSPICE to confirm the presented theory.
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    Electronically tunable multiple-input single-output voltage-mode multifunction filter employing simple CMOS OTAs
    (2010-12-01)
    Kumngern, Montree
    ;
    Torteanchai, Usa
    ;
    Dejhan, Kobchai
    This paper describes a new electronically tunable four inputs and single output voltage-mode universal biquadratic filter based on simple CMOS operational transconductance amplifiers (OTAs) and grounded capacitors. The proposed filter provides low-pass, high-pass, band-pass, band-stop and all-pass voltage responses at a high impedance input terminal, which enable easy cascadability. The circuit parameters ω<inf>o</inf> and Q can be orthogonally set the circuit component. The parameter ω<inf>o</inf> also offers an electronic control by adjusting the transconductance gain of the OTA. For realizing all the filter responses, no critical component matching condition is required and all the parameter sensitivities are low. PSPICE simulation results are performed to confirm the theoretical analysis. © 2010 IEEE.
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    Electronically tunable high-input impedance voltage-mode universal biquadratic filter based on simple CMOS OTAs
    (2010-10-01)
    Kumngern, Montree
    ;
    Knobnob, Boonying
    ;
    Dejhan, Kobchai
    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. © 2009 Elsevier GmbH. All rights reserved.
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    High frequency and high precision CMOS half-wave rectifier
    (2010-10-01)
    Kumngern, Montree
    ;
    Knobnob, Boonying
    ;
    Dejhan, Kobchai
    In this paper, a new high frequency and high precision half-wave rectifier circuit which is very suitable for CMOS technology implementation is presented. The system comprises a voltage to current converter, a dual output precision current-mode half-wave rectifier, and two current to voltage converters. An input voltage signal is converted into a current signal by using a current conveyor and a MOS resistor. The current signal is rectified using a dual output class-AB precision rectifier cell and then converted into two output voltages by using grounded MOS resistors. This class-AB current-mode precision rectifier is employed for providing high frequency performance. Simulated rectifier results based-on a 0.5 μm CMOS technology with ±1.2 V supply voltage demonstrates very high operating frequency, very precise rectification and good temperature stability. © Springer Science+Business Media, LLC 2010. © Springer Science+Business Media, LLC 2010.