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0.5 V Multiple-Input Fully Differential Operational Transconductance Amplifier and Its Application to a Fifth-Order Chebyshev Low-Pass Filter for Bio-Signal Processing
(MDPI, 2024-04-01) Kulej, Tomasz; Khateb, Fabian; Kumngern, Montree
This paper presents a multiple-input fully differential operational transconductance amplifier (MI-FD OTA) with very low power consumption. To obtain a differential MOS pair with minimum supply voltage and minimum power consumption, the multiple-input bulk-driven MOS transistor operating in the subthreshold region is used. To show the advantage of the MI-FD OTA, a fifth-order Chebyshev filter was used to realize a low-pass filter capable of operating with a supply voltage of 0.5 V and consuming 60 nW at a nominal setup current of 3 nA. The proposed filter uses five MI-FD OTAs and five capacitors. The total harmonic distortion (THD) was 0.97% for a rail-to-rail sinusoidal input signal. The MI-FD OTA and the filter application were designed and simulated in the Cadence environment using a 0.18 mu m CMOS process from TSMC. The robustness of the design was confirmed by Monte Carlo analysis and process, voltage, and temperature corner analysis.
1 V Electronically Tunable Differential Difference Current Conveyors Using Multiple-Input Operational Transconductance Amplifiers
(MDPI, 2024-02-28) Kumngern, Montree; Khateb, Fabian; Kulej, Tomasz; Langhammer, Lukáš
This paper presents electronically tunable current conveyors using low-voltage, low-power, multiple-input operational transconductance amplifiers (MI-OTAs). The MI-OTA is realized using the multiple-input bulk-driven Metal Oxide Semiconductor transistor (MIBD-MOST) technique to achieve minimum power consumption. The MI-OTA also features high linearity, a wide input range, and a simple Complementary Metal Oxide Semiconductor (CMOS). Thus, high-performance electronically tunable current conveyors are obtained. With the MI-OTA-based current conveyor, both an electronically tunable differential difference current conveyor (EDDCC) and a second-generation electronically tunable current conveyor (ECCII) are available. Unlike the conventional differential difference current conveyor (DDCC) and second-generation current conveyor (CCII), the current gains of the EDDCC and ECCII can be controlled by adjusting the transconductance ratio of the current conveyors. The proposed EDDCC has been used to realize a voltage-to-current converter and current-mode universal filter to show the advantages of the current gain of the EDDCC. The proposed current conveyors and their applications are designed and simulated in the Cadence environment using 0.18 mu m TSMC (Taiwan Semiconductor Manufacturing Company) CMOS technology. The proposed circuit uses +/- 0.5 V of power supply and consumes 90 mu W of power. The simulation results are presented and confirm the functionality of the proposed circuit and the filter application. Furthermore, the experimental measurement of the EDDCC implemented in the form of a breadboard connection using a commercially available LM13700 device is presented.
ChemFET gas nanosensor arrays with alignment windows for assembly of single nanowires
(Springer, 2023-04-13) Chmela, Ondřej; Gablech, Imrich; Sadílek, Jakub; Brodský, Jan; Vallejos Vargas, Stella
This work focuses on the fabrication and characterization of ChemFET (Chemical Field-Effect Transistor) gas nanosensor arrays based on single nanowire (SNW). The fabrication processes include micro and nanofabrication techniques enabled by a combination of ultraviolet (UV) and e-beam lithography to build the ChemFET structure. Results show the integration and connection of SNWs across the multiple pairs of nanoelectrodes in the ChemFET by dielectrophoresis process (DEP) thanks to the incorporation of alignment windows (200-300 nm) adapted to the diameter of the NWs. Measurements of the SNW ChemFET array's output and transfer characteristics prove the influence of gate bias on the drain current regulation. Tests upon hydrogen (H-2) and nitrogen dioxide (NO2) as analyte models of reducing and oxidizing gases show the ChemFET sensing functionality. Moreover, results demonstrate better response characteristics to H-2 when the ChemFET operates in the subthreshold regime. The design concepts and methods proposed for fabricating the SNW-based ChemFET arrays are versatile, reproducible, and most likely adaptable to other systems where SNW arrays are required.
Bilinear Double-Order Filter Designs and Application Examples
(IEEE, 2024-01-22) Nako, Julia; Psychalinos, Costas; Khateb, Fabian; Elwakil, Ahmed
A novel kind of non-integer order bilinear filters, named double-order bilinear filters, is introduced in this work. They are based on the employment of two non-integer orders, offering the maximum design flexibility in comparison with their fractional-order and power-law counterparts. An attractive offered benefit is that this is achieved without increasing the circuit complexity, since the proposed structure is capable of realizing all non-integer kinds of filters. Two design examples are provided, where it is shown that lead/lag compensators utilized in control applications and low/high shelving filters employed in acoustic applications are actually bilinear filters with suitably selected pole/zero frequencies. Simulation and experimental results, using the OrCAD PSpice simulator and a Field Programmable Analog Array device, respectively, support the findings of this work.
Smart bactericide based on reduced graphene oxide decorated with copper and zinc nanoparticles
(Springer Nature, 2023-10-24) Bytešníková, Zuzana; Pečenka, Jakub; Tekielska, Dorota; Pekárková, Jana; Ridošková, Andrea; Bezdička, Petr; Kiss, Tomáš; Eichmeier, Aleš; Adam, Vojtěch; Lukas, Richtera
Graphene oxide (GO) synthesised by modified Tour's method was decorated with copper and zinc nanoparticles (NPs) and simultaneously reduced by sodium borohydride to obtain a nanocomposite of reduced GO with copper and zinc NPs (rGO-Cu-Zn). The nanocomposite rGO-Cu-Zn was characterised by transmission electron microscopy (TEM), energy dispersive X-ray (EDX) spectroscopy, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The rGO-Cu-Zn was tested against Xanthomonas euvesicatoria (X. euvesicatoria), which attacks tomatoes and causes bacterial spots (BSs), and compared with the commercial product Champion 50 WG. Total bacterial growth inhibition was observed for the 1% rGO-Cu-Zn, whereas Champion 50 WG at the same concentration inhibited but did not eradicate all the bacterial colonies. To evaluate the negative effect of the rGO-Cu-Zn on the molecular level, the expression of the genes associated with the action of abiotic and biotic stress factors was analysed. Gene expression in the plants treated with 10% rGO-Cu-Zn did not exhibit a noticeable increase.

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