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    Item type:Publication,
    Compact active analog device for novel applications useful for sensing and measurement
    (2024-08-01)
    Sotner, Roman
    ;
    Jerabek, Jan
    ;
    Polak, Ladislav
    ;
    Jaikla, Winai
    ;
    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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    Design of Phase-Locked Loop Using Special Analog Multipliers and Voltage Buffers: Demodulation of Transposed Signals from Sensors
    (2024-01-01)
    Svoboda, Marek
    ;
    Sotner, Roman
    ;
    Polak, Ladislav
    ;
    Jerabek, Jan
    ;
    Jaikla, Winai
    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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