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    Current-mode MISO filter using CCCDTAs and grounded capacitors
    (2015-07-01) ;
    Jantakun, Adirek
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    ;
    This paper presents the current-mode multi-input single-output (MISO) biquadratic filter using current-controlled current differencing tranconductance amplifier (CCCDTA) as an active building block. The proposed circuit comprises three CCCDTAs and two grounded capacitors performing completely standard functions: low-pass, high-pass, band-pass, bandreject and all-pass functions and does not require double input current signals as well as inverting input currents. The pole frequency and quality factor of the proposed circuit can be adjusted electronically/independently via dc bias currents. In addition, the filter circuit has low-input and high-output impedance which facilitates easy connecting for current-mode circuit. The proposed circuit uses all grounded capacitors which is very suitable to further develop into an integrated circuit and without requiring any matching condition. Moreover, the active and passive sensitivities are low. The PSPICE simulation results are included to show the workability of the proposed circuit.
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    Synthesis of electronically tunable multifunction biquad filter using voltage differencing differential input buffered amplifiers
    (2025-02-01)
    Bunrueangsak, Sirigul
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    ; ; ;
    Biquad filters are commonly used in analog circuits for various purposes in signal processing and communication applications. We synthesize an analog active biquad filter with five types of voltage-mode filtering functions. The filter is synthesized using a parallel passive resistor-inductor-capacitor (RLC) network and unity-gain voltage differencing amplifier. A voltage differencing differential input buffered amplifier (VD-DIBA) is the main active component, and the biquad filter has a three-input single-output (TISO) topology. By replacing the passive inductor and resistor with VD-DIBA-based inductance and resistance simulators with a subtractor, the TISO voltage-mode versatile filter is obtained from two VD-DIBAs, one resistor, and two capacitors connected to the ground. The proposed filter can provide five types of voltage-mode filtering functions: inverting bandpass and lowpass responses as well as noninverting band-stop, high-pass, and all-pass responses. The all-pass filter requires no additional active components. The three input voltage nodes have high impedance, and a low-impedance output voltage node facilitates cascade connections without using additional voltage buffers. In addition, the natural frequency and quality factor can be electronically tuned. The quality factor is controlled without disturbing the passband gain and natural frequency. The proposed filter is simulated and verified experimentally in the Personal Simulation Program with Integrated Circuit Emphasis (PSPICE) and through laboratory tests employing VD-DIBAs implemented using commercially available components.
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    Single Active Element Based Electronically Controllable Capacitance Multiplier
    (2022-07-15) ;
    Huaihongthong, Pintira
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    ; ;
    The realization of capacitance multiplier using the versatile active building block, namely voltage differencing differential difference amplifier (VDDDA) is presented in this paper. The realized capacitance multiplier is very simple consisting of one VDDDA, one MOS resistor (RM) and one grounded capacitor which is attractive for integration. The multiplication factor (KC) of the realized circuit can be electronically controlled via the bias current (IB) and control voltage (VC) without the need of any matching condition of active and passive element. Moreover, the multiplication factor can be adjusted to be more or less than one. The performances of the presented capacitance multiplier are verified through Pspice simulation using CMOS VDDDA in 0.18μm TSMC technology with ±0.9V power supplies. The multiplication factor is designed to be KC=2 by choosing VC=0.85V, IB=50μA and C=30 pF. The simulated multiplication factor is around 1.98. The simulated operational frequency range is around three decades (6.16 kHz-8.91MHz). The performances of the proposed circuit are also verified by the experiment using VDDDA implemented from the commercial ICs, AD830 and LM13700 with ±5V power supplies. The experiment is conducted under the same multiplication factor (KC=2) as the simulation by choosing RM=0.27 kω (1% passive resistor), IB=96.2μA and C=1nF. The experimental multiplication factor is around 2.06. The experimental operational frequency range is around three decades (1kHz-1.25MHz). By adjusting the bias current from 17.67μA to 400 μA, the experimental multiplication factor is controllable from 11.47 to 0.48. The percent deviation of the theoretical and experimental multiplication factor is lower than 5% when the value of bias current is greater than 39μA. These deviations stem from the effect of the parasitic capacitance and resistance in VDDDA. Moreover, the application example of the presented capacitance multiplier as the sinusoidal oscillator is presented. The performances of the presented oscillator verified via the experiment are well consistent with theoretical anticipation.
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    Current-mode variable current gain first-order allpass filter employing CFTAs
    (2013-01-01)
    Iamarejin, Anirut
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    Maneewan, Suwat
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    In this study, a current-mode first order allpass filter using current follower transconductance amplifiers (CFTAs) is proposed. The features of the circuit are that: the pole frequency, phase response and current gain can be electronically controlled via the input bias current: the circuit description is very simple, consisting of 2 CFTAs, 1 resistor and 1 grounded capacitor, without any component matching requirements. Consequently, the proposed circuit is very appropriate to further develop into an integrated circuit. Low input and high output impedances of the proposed configuration enable the circuit to be cascaded in current-mode without additional current buffers. The PSpice simulation results are depicted. The given results agree well with the theoretical anticipation.
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    Comparison of Two Solutions of Quadrature Oscillators With Linear Control of Frequency of Oscillation Employing Modern Commercially Available Devices
    (2015-11-23)
    Sotner, Roman
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    Jerabek, Jan
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    Langhammer, Lukas
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    Polak, Josef
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    Herencsar, Norbert
    This paper proposes two circuits of frequency-controlled oscillators, whose structures are based only on simple commercially available active elements with minimum number of terminals, in particular, the differential voltage buffer, controllable voltage amplifier and electronically controllable current conveyor. Two methods for achieving linear control (tuning) of frequency of oscillations (FO) are discussed. The first method employs a simple structure. However, the generated signal level (amplitude) depends on the tuning process. This is a drawback of this method. The second method solves this drawback completely, and the generated signals have constant amplitudes during the tuning of FO. The expected behavior is confirmed by laboratory experiments utilizing commercially available high-speed active elements (current- and voltage-mode multipliers, video difference amplifier). Operational range was tested from frequencies of hundreds of kHz up to frequencies of tens of MHz.
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    CCCIIs-based sinusoidal quadrature oscillators with non-interactive control of condition and frequency
    (2014-01-01)
    Summart, Saksit
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    Thongsopa, Chanchai
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    The paper presents two current-mode quadrature oscillators with non-interactive two current controls for both of the condition of oscillation (CO) and the frequency of oscillation (FO) using current controlled current conveyors (CCCIIs). The proposed oscillators can provide two sinusoidal output currents with 90 degrees phase difference. It also provides high output impedances that make the circuit can directly drive load without additional current buffer. The condition of oscillation and frequency of oscillation can be controlled by adjusting the bias currents of the CCCIIs. The proposed circuits use only grounded capacitors without any external resistor which is very appropriate for further development into an integrated circuit. The results of PSPICE simulation program are corresponding to the theoretical analysis. Copyright © 2012 The Council of Scientific and Industrial Research, New Delhi.
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    Design of Phase-Locked Loop Using Special Analog Multipliers and Voltage Buffers: Demodulation of Transposed Signals from Sensors
    (2024-01-01)
    Svoboda, Marek
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    Sotner, Roman
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    Polak, Ladislav
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    Jerabek, Jan
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    Phase-locked loops (PLLs) are versatile electronic circuits that, among others, are used in various sensor applications (e.g., medical) for their ability to generate stable and precise clock signals. This article introduces a novel PLL-based frequency demodulation system designed for processing of very slow signals, ranging from a few Hz to several hundreds of Hz, with amplitudes in the order of several hundreds of millivolts. The system incorporates specialized analog multipliers tailored for essential PLL components, including the voltage-controlled oscillator, phase detector, loop filter with variable DC offset, and baseband filter, all optimized for the purpose of frequency demodulation. These multipliers were fabricated using the TSMC 0.18~μ m, 1.8 V CMOS process. The primary design objectives are simplicity, reduced complexity, low power consumption (merely 15 mW), and versatility for applications in sensing engineering. To validate the functionality of the proposed PLL system under practical conditions, we present an example of electrocardiogram and photoplethysmogram signal demodulation, demonstrating its operational performance.
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    Compact active analog device for novel applications useful for sensing and measurement
    (2024-08-01)
    Sotner, Roman
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    Jerabek, Jan
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    Polak, Ladislav
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    Andriukaitis, Darius
    The presented research introduces a novel approach to modern modular active device and provides various practical application examples tailored for industrial sensing readouts. Straightforward implementation of single active device-based topologies in frequency bands from kHz up to MHz is presented. These applications include: an electronically linearly tunable special band-pass filter that can be easily modified into a voltage-controlled oscillator, a two-port quadratic transformer, an amplitude modulator, and an equalization circuit (which serves as a fractional-order differentiator and integrator). These circuits benefit from high-impedance voltage input and low-impedance output (easily matched to 50 Ω), high processed signal levels (often reaching hundreds of mV), and simplified topologies without redundant passive elements. These features are especially valuable in tunable and configurable solutions for modern communication, sensing, audio, and consumer electronic systems, as well as in modeling various physical and biological systems. The experiments have been provided by simulations and measurements using device VCA824.
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    Electronically tunable current-mode quadrature oscillator derived from first-order allpass filter
    In this study, an electronic controllability current-mode quadrature oscillator based on first-order all pass filter employing current follower cascaded Tran conductance amplifier (CFCTA) is presented. The proposed oscillator uses two CFCTAs, two electronic resistors and two grounded capacitor, which is easier for monolithic IC implementation. The condition of oscillation (CO) and frequency of oscillation are electronically and independently controlled which is well suited to use in modern electronic devices controlled by microprocessor. Moreover, the oscillator possesses high output impedances and thus it enables simple current-mode cascading. The PSPICE simulation results are included, verifying the workability of the proposed current-mode oscillator. The given results agree well with the theoretical anticipation.
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    Electronically controllable grounded inductance simulators using single commercially available IC: LT1228
    The grounded inductance simulators using available commercially integrated circuit (IC) are proposed in this paper. The three types of active inductor called parallel R and L, series R and L and pure L are achieved. The proposed inductance simulators consist of single available commercially IC from Linear Technology Inc. called LT1228 with a resistor and a capacitor. The tune of inductance and resistance value can be done electronically. The proposed inductance simulators don't require any active and passive component matching condition. The performances of proposed circuit are verified through PSPICE simulation and experiment. To show the usability of the proposed simulators, they are used to realize the sinusoidal oscillator, second order bandpass filter and second order band-reject filter. The workability of these applications is experimented. The results agree well with theoretical expect.