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Author: search.filters.author.Prapakorn, Nattawit

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    Log-domain current-mode quadrature sinusoidal oscillator
    (2011-12-14)
    Prommee, Pipat
    ;
    Prapakorn, Nattawit
    ;
    Swamy, M. N.S.
    A log-domain current-mode quadrature sinusoidal oscillator based on lossless integrators is presented. The circuit is a direct realization of a first-order differential equation for obtaining the lossy and lossless integrators. Each of the log-domain lossless integrators is realized by using only NPN transistors and a grounded capacitor for achieving low-power and fast response. The proposed oscillator uses two-lossless integrator loop which can be electronically tuned through bias currents. A validated BJT model which is used in SPICE simulation operated from a single power supply as low as 2.5 V. The oscillation frequency is controlled over four decades of frequency. The total harmonic distortions for two-phases QSO (12 MHz) is obtained around 0.93% which enables fully integrated in telecommunication systems. The proposed circuit is also suitable for high-frequency applications. Nonideality studies are included and PSpice simulation results confirm the theoretical results.
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    Quadrature sinusoidal oscillator based on log-domain high-pass and low-pass filters
    (2011-10-13)
    Prommee, Pipat
    ;
    Prapakorn, Nattawit
    ;
    Somdunyakanok, Montri
    A log-domain current-mode quadrature sinusoidal oscillator (QSO) based on low-pass (LP) and high-pass (HP) filters is presented. The log-domain QSO is realized by using only 18 NPN transistors and 2 grounded capacitors for achieving low-power and fast response. The proposed oscillator uses a cascade connecting the LP and HP which can be electronically tuned through bias current. Frequency of oscillation can be tuned over a wide-range with a low-power supply as 2V which is suitable for IC production. The power consumption is obtained around 5.5mW at 100μA of bias current. The oscillation frequency is controlled over four decades of frequency. The total harmonic distortion of QSO at 10.63MHz is obtained around 1.25%. The proposed circuit is suitable for high-frequency applications. PSpice simulation confirms the theoretical results. © 2011 IEEE.