Now showing 1 - 5 of 5
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    Item type:Publication,
    Cascadable First-Order and Second-Order Inverse Filters Based on Second-Generation Voltage Conveyors
    (2025-02-01) ;
    Likhitkitwoerakul, Nutcha
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    Faseehuddin, Mohammad
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    This study introduces four novel configurations of first-order and second-order multifunction inverse filters in both voltage-mode (VM) and current-mode (CM) using second-generation voltage conveyors (VCIIs). The first-order VM and CM inverse filters utilize only three passive components together with one VCII for VM and two VCIIs for CM realizations, which can provide lowpass and highpass inverse filter responses. The latter, second-order VM and CM multifunction inverse filters, can be constructed using the corresponding first-order inverse filters as their core circuits. These filters offer all the basic inverse filter functions, including lowpass, bandpass, and highpass inverse responses with all gains obtained from the same design. All the inverse filter realizations are cascadable. No component matching requirements are necessary for all filter responses. The non-ideal effects of the VCII on the performance of the proposed inverse filters are thoroughly examined. To prove the feasibility of the designs, the PSPICE program performed several simulations, utilizing model parameters of 0.18 µm CMOS technology. Some testing experiments were conducted using the commercially available IC-type AD844s for evaluating the practical performance of the designed inverse filters.
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    Item type:Publication,
    VDTA-Based Mixed-Mode Inverse Filter and Its Application to Mixed-Mode PID Controller
    (2026-04-01) ; ;
    Faseehuddin, Mohammad
    ;
    This paper presents a novel voltage differencing transconductance amplifier (VDTA)-based mixed-mode inverse filter capable of operating in voltage mode, transadmittance mode, transimpedance mode, and current mode using a single topology. The proposed configuration employs only three VDTAs with two resistors and three capacitors, offering low component count, high input/output impedance flexibility, and no requirement for component matching. It simultaneously realizes first-order inverse lowpass and highpass, as well as second-order inverse bandpass responses. A comprehensive non-ideal analysis, which includes the effects of VDTA parasitic impedances, determines the practical operating frequency range. The design is validated through PSPICE simulations using 0.18 μm CMOS technology, showing close alignment between theoretical predictions and simulation results, with cutoff frequencies of approximately 1.60 MHz and low power consumption of 0.972 mW. Further analyses confirm orthogonal tuning capability, acceptable temperature stability, and robustness against component tolerances. In a practical application, the proposed inverse filter is employed to implement a mixed-mode PID controller, which significantly improves transient response characteristics by reducing rise time, settling time, and steady-state error. These findings highlight the effectiveness and versatility of the proposed design for analog signal processing and control system applications.
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    Item type:Publication,
    Grounded Series and Parallel RL/RC Immittance Simulators Using a Single Second-Generation Voltage Conveyor
    (2026-01-01) ;
    Tangjit, Jetwara
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    Faseehuddin, Mohammad
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    This work proposes the active simulation of grounded series and parallel resistive-inductive (RL) and resistive-capacitive (RC) immittance functions employing a single second-generation voltage conveyor (VCII) and three passive components. The two configurations are designed for series RL and RC immittance simulation and RL and parallel RC immittance simulation, respectively. All of the simulated immittance functions can be realized without any specific component matching or cancellation limitations. The proposed series and parallel RL and RC immittance function simulators have been simulated with PSPICE program based on 0.18 µm CMOS process parameters to validate the theoretical study. The first-order inverse filters, biquadratic filter, and synthetic lossless inductor applications, constructed with the proposed simulator circuits, are designed and evaluated to further demonstrate the practical usefulness of the designed simulators.
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    Item type:Publication,
    Tunable mixed-mode voltage differencing buffered amplifier-based universal filter with independently high-q factor controllability
    (2021-10-01) ;
    Faseehuddin, Mohammad
    ;
    Herencsar, Norbert
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    This paper proposes the design of a mixed-mode universal biquad configuration, which realizes generic filter functions in all four possible modes, namely voltage mode (VM), current mode (CM), transadmittance mode (TAM), and transimpedance mode (TIM). The filter architecture employs two voltage differencing buffered amplifiers (VDBAs), two resistors and two capacitors, and can provide lowpass (LP), bandpass (BP), highpass (HP), bandstop (BS), and allpass (AP) bi-quadratic filtering responses without any circuit alteration. All passive elements used are grounded, except VM. The circuit not only allows for the electronic tuning of the natural angular frequency (ωo), but also achieves orthogonal tunability of the quality factor (Q). It also provides the feature of availability of output voltage at the low-output impedance terminal in VM and TIM, and does not require inverting-type or double-type input signals to realize all the responses. Moreover, in all modes of operation, the high-Q filter can be easily obtained by adjusting a single resistance value. Influences of the VDBA nonidealities and parasitic elements are also discussed in detail. PSPICE simulations with TSMC 0.18-µm CMOS process parameters and experimental testing results with commercially available IC LT1228s have been used to validate the theoretical predictions.
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    Item type:Publication,
    All-Grounded Passive Component Mixed-Mode Multifunction Biquadratic Filter and Dual-Mode Quadrature Oscillator Employing a Single Active Element
    (2025-09-01) ;
    Tangjit, Jetwara
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    Faseehuddin, Mohammad
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    ;
    This paper introduces a compact analog configuration that concurrently realizes a mixed-mode biquadratic filter and a dual-mode quadrature oscillator (QO) by employing a single differential differencing gain amplifier (DDGA) and all-grounded passive components. The proposed design supports four fundamental operation modes—voltage-mode (VM), current-mode (CM), trans-impedance-mode (TIM), and trans-admittance-mode (TAM)—utilizing the same circuit topology without structural modifications. In filter operation, it offers low-pass, high-pass, band-pass, band-stop, and all-pass responses with orthogonal and electronic pole frequency and quality factor. In oscillator operation, it delivers simultaneous voltage and current quadrature outputs with independent tuning of oscillator frequency and condition. The grounded-component configuration simplifies layout and enhances its suitability for monolithic integration. Numerical simulations in a 0.18-μm CMOS process with ±0.9 V supply confirm theoretical predictions, demonstrating precise gain-phase characteristics, low total harmonic distortion (<7%), modest sensitivity to 5% component variations, and stable operation from −40 °C to 120 °C. These results, combined with the circuit’s low component count and integration suitability, suggest strong potential for future development in low-power IoT devices, adaptive communication front-ends, and integrated biomedical systems.