Centrum senzorických, informačních a komunikačních systémů
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- ItemMeasurements of Ultra Wide Band In-vehicle channel - statistical description and TOA positioning feasibility study(Springer, 2015-08-11) Blumenstein, Jiří; Prokeš, Aleš; Mikulášek, Tomáš; Maršálek, Roman; Zemen, Thomas; Mecklenbräuker, ChristophThis paper reports on a real-world wireless channel measurement campaign for in-vehicle scenarios in the ultra wide bandwidth (UWB) frequency range of 3-11 GHz. The effects of antenna placement in the vehicle's passenger compartment, as well as the effects due to the presence of passengers are studied. The measurements have been carried out in the frequency domain and the corresponding channel impulse responses (CIRs) have been estimated by inverse Fourier transform. The inuence of a specifc band group selection within the whole UWB range is also given. Statistical analysis of the measured channel transfer functions gives a description of the wireless channel statistics in the form of a generalized extreme value process. The corresponding parameter sets are estimated and documented for all permutations of antenna placement and occupancy patterns inside the vehicle's passenger compartment. Further, we have carried out a feasibility study of an in-vehicle UWB based localization system based on the time of arrival (TOA)). The positioning performance is evaluated in terms of average error and standard deviation.
- ItemNew Compact VM Four-Phase Oscillator Employing Only Single Z-Copy VDTA And All Grounded Passive Elements(Kaunas University of Technology, 2013-12-16) Herencsár, Norbert; Šotner, Roman; Koton, Jaroslav; Mišurec, Jiří; Vrba, KamilIn this paper, a new compact voltage-mode four-phase oscillator employing single z-copy voltage differencing transconductance amplifier (ZC-VDTA) and only grounded passive elements is introduced. The use of only grounded capacitors and resistors makes the proposed circuit ideal for integrated circuit implementation. The condition of oscillation and the frequency of oscillation are independently adjustable. The passive and active sensitivities of the proposed circuit configuration are low. Experimental measurement results using readily available Maxim Integrated ICs MAX435 are given to prove the theory.
- ItemVoltammetry as a Tool for Characterization of CdTe Quantum Dots(MDPI, 2013-06-27) Adam, Pavlína; Vaculovičová, Markéta; Hubálek, Jaromír; Adam, Vojtěch; Kizek, RenéElectrochemical detection of quantum dots (QDs) has already been used in numerous applications. However, QDs have not been well characterized using voltammetry, with respect to their characterization and quantification. Therefore, the main aim was to characterize CdTe QDs using cyclic and differential pulse voltammetry. The obtained peaks were identified and the detection limit (3 S/N) was estimated down to 100 fg/mL. Based on the convincing results, a new method for how to study stability and quantify the dots was suggested. Thus, the approach was further utilized for the testing of QDs stability
- ItemNew Resistorless and Electronically Tunable Realization of Dual-Output VM All-Pass Filter Using VDIBA(Springer, 2013-01-07) Herencsár, Norbert; Minaei, Shahram; Koton, Jaroslav; Yuce, Erkan; Vrba, KamilIn this paper, a new active element called voltage differencing inverting buffered amplifier (VDIBA) is presented. Using single VDIBA and a capacitor, a new resistorless voltage-mode (VM) first-order all-pass filter (APF) is proposed, which provides both inverting and non-inverting outputs at the same configuration simultaneously. The pole frequency of the filter can be electronically controlled by means of bias current of the internal transconductance. No component-matching conditions are required and it has low sensitivity. In addition, the parasitic and loading effects are also investigated. By connecting two newly introduced APFs in open loop a novel second-order APF is proposed. As another application, the proposed VM APF is connected in cascade to a lossy integrator in a closed loop to design a four-phase quadrature oscillator. The theoretical results are verified by SPICE simulations using TSMC 0.18 um level-7 CMOS process parameters with +-0.9 V supply voltages. Moreover, the behavior of the proposed VM APF was also experimentally measured using commercially available integrated circuit OPA860 by Texas Instruments.
- ItemStudy of Small-signal Model of Simple CMOS Amplifier with Instability Compensation of Positive Feedback Loop(De Gruyter Open, 2015-07-06) Šotner, Roman; Jeřábek, Jan; Herencsár, Norbert; Vrba, Kamil; Lahiri, Abhirup; Dostál, TomášThe paper deals with precise analysis of simple AC variable gain CMOS amplifier. The circuit can be used as a simple voltage follower (6 MOS transistors are required) or amplifier. The main attention of this work is focused on a small-signal model of the proposed block and effects of additional passive network leading to compensation of its instability. The continuous gain adjusting in range from 1.1 to 10 (0.8 – 20 dB and with bandwidth 4.9 - 90 MHz at 5 pF load capacitance) is possible and the proposed amplifier is suitable for implementation in systems, where lower range of gain adjusting and large dynamical range is required. Theoretical analyses are supported by PSpice simulations (TSMC 0.18 um technological models) and experimental measurements with commercially available CMOS transistor fields (ALD1106/7) also confirm the discussed behavior of the amplifier.