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Author: search.filters.author.Dejhan, KobchaiSubject: search.filters.subject.Electronically-controlled

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    Single-input multiple-output tunable log-domain current-mode universal filter
    (2013-08-27)
    Prommee, Pipat
    ;
    Dejhan, Kobchai
    This paper describes the design of a currentmode single-input multiple-output (SIMO) universal filter based on the log-domain filtering concept. The circuit is a direct realization of a first-order differential equation for obtaining the lossy integrator circuit. Lossless integrators are realized by log-domain lossy integrators. The proposed filter comprises only two grounded capacitors and twentyfour transistors. This filter suits to operate in very high frequency (VHF) applications. The pole-frequency of the proposed filter can be controlled over five decade frequency range through bias currents. The pole-Q can be independently controlled with the pole-frequency. Nonideal effects on the filter are studied in detail. A validated BJT model is used in the simulations operated by a single power supply, as low as 2.5 V. The simulation results using PSpice are included to confirm the good performances and are in agreement with the theory.
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    Log-domain multiphase sinusoidal oscillator
    (2011-10-13)
    Prommee, Pipat
    ;
    Sra-Ium, Napat
    ;
    Dejhan, Kobchai
    This paper describes the design of a log-domain multiphase sinusoidal oscillator (MSO). The circuit is a direct realization of a first-order differential equation for obtaining the non-inverting and inverting lossy integrators. Each integrator comprises only a grounded capacitor and six transistors. The proposed MSO can be instantaneously controlled over wide frequency range by controlling the bias currents. The high-frequency of oscillation and oscillation condition can also be independently tuned which are indicated proposed MSO suitability in communications and high-frequency applications. The power consumption is obtained around 5.78mW at 100μA of bias current based on 2V single power supply. The oscillation frequency is controlled over four decades of frequency. The total harmonic distortion of four-phases (11.33MHz) is obtained around 1.12%. © 2011 IEEE.
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    Tunable current-mode log-domain universal filter
    (2010-08-31)
    Prommee, Pipat
    ;
    Somdunyakanok, Montri
    ;
    Angkeaw, Krit
    ;
    Dejhan, Kobchai
    This paper describes the design of a current-mode universal filter based on log-domain filtering concept. The circuit is a direct realization of a first-order differential equation for obtaining the two integrators loop structure. Lossless integrators are realized by log-domain lossy integrators. The proposed filter comprises only two grounded capacitors and sixteen transistors. Frequency response of the proposed filter can be instantaneously controlled over a very wide frequency range by controlling current. Quality factor is independently controlled by another current. It can be seen that the proposed circuit suites for high-frequency applications. A validated BJT model that used in simulation is operated by a single power supply as low as 2.5V. The wide-range frequency response is controlled over five decades of current controlled. ©2010 IEEE.