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Author: search.filters.author.Jaikla, WinaiSubject: search.filters.subject.Capacitance multiplier

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    Single Active Element Based Electronically Controllable Capacitance Multiplier
    (2022-07-15)
    Jaikla, Winai
    ;
    Huaihongthong, Pintira
    ;
    Siripongdee, Surapong
    ;
    Chaichana, Amornchai
    ;
    Suwanjan, Peerawut
    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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    A Single Parameter Voltage Adjustable Immittance Topology for Integer- And Fractional-Order Design Using Modular Active CMOS Devices
    (2021-01-01)
    Sotner, Roman
    ;
    Jerabek, Jan
    ;
    Polak, Ladislav
    ;
    Prokop, Roman
    ;
    Jaikla, Winai
    A simple single parameter adjustable immittance concept designed with modular active devices, fabricated in I3T $25~0.35~\mu \text{m}$ 3.3 V CMOS process of ON Semiconductor, is introduced. The proposed devices employ an integer-order capacitor and specifically designed fractional-order capacitors (sometimes called constant phase elements). The proposed active topology consists of two simple active elements, namely a linearly voltage adjustable operational transconductance amplifier and a voltage differencing unity gain voltage follower/buffer, and only two passive elements, i.e. redundancy is minimized. The designed topology offers generation of an adjustable immittance having both the capacitive and inductive character. The importance of the order as well as the value of the pseudo-capacitance for design and analyzes are shown, including all important parasitic features for estimation of expected operational bandwidth which have to be considered in the design. The operational bandwidth is determined by high values of approximants of fractional-order capacities (225, 56 and $8.8~\mu \text{F}$ /seĉ1- $\alpha $ , where $\alpha $ represents the order equal to 0.25, 0.5 and 0.75, respectively). These parameters result into ranges between tens of Hz and units-tens of kHz. The adjustability of the transconductance from 70 to $700~\mu \text{S}$ by the driving voltage between 0.05 and 0.5 V offers approximately one decade change of equivalent capacitance and inductance. Laboratory-based experiments done with a fabricated prototype confirmed the theoretical presumptions.
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    Operational frequency bandwidth rescalable implementations of constant phase devices
    (2019-04-01)
    Sotner, Roman
    ;
    Jerabek, Jan
    ;
    Langhammer, Lukas
    ;
    Polak, Ladislav
    ;
    Jaikla, Winai
    This paper presents and verifies a method for rescalability of operational bandwidth in constant phase devices (two-port elements, two-port transfer blocks). Most importantly, in comparison with a standard approach, it allows to utilize suitable values of capacitance in the case of operation at low-frequency bands. The capacitance multipliers based on a controllable variable gain amplifier are implemented in examples of simple fractional-order systems (two-port integrators). These examples consist of novel bilinear immittances with independently settable zero and pole frequency coordinates, based on widespread commercially available current conveyors of second generation. The capacitance multiplier extends features of the bilinear immittance and full implementation of the system. PSpice simulations, using off-the-shelf elements, confirm operability of the proposed concept.