2010/1

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    Systematic Design of Fully Balanced Differential Current-Mode Multiple-Loop Feedback Filters Using CFBCCII
    (Společnost pro radioelektronické inženýrství, 2010-04) Wang Chunhua; Leng Yang; Zhang Qiujing; Fei Yu
    In this paper, a systematic design method producing balanced current-mode filters is proposed, using current controlled fully balanced second-generation current conveyor circuit (CFBCCII). In this method, many kind of all-pole multiple loop feedback (MF) current mode balanced filters can be obtained, all the produced filters have fully balance structures. Moreover, the frequency of the filters can be electronically adjustable. The produced nth-order filters are constructed by n CFBCCIIs and 2n grounded capacitors, no resistors are needed. The sensitivities of the filters and influences of CFBCCII parasitic elements on filters are analyzed.
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    New Grounded and Floating Simulated Inductance Circuits using Current Differencing Transconductance Amplifiers
    (Společnost pro radioelektronické inženýrství, 2010-04) Prasad, Dinesh; Bhaskar, D. R.; Singh, A. K.
    Current differencing transconductance amplifier (CDTA) is receiving considerable attention as a building block for current-mode (CM) analog signal processing / signal generation. In this paper, new CDTA based lossless grounded and floating inductance simulation circuits have been proposed. The proposed grounded simulated inductance circuit employs two CDTAs and a single grounded capacitor whereas the floating simulated inductance circuit employs three CDTAs and a grounded capacitor. The circuit for grounded inductance does not require any realization conditions whereas in case of floating inductance only equality of two transconductances is needed (which can be easily maintained in practice by ensuring equal dc bias currents in the two transconductance amplifiers). Some sample results demonstrating the applications of the new simulated inductors using CMOS CDTAs have been given to confirm the workability of the new circuits.
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    Global Evolutionary Algorithms in the Design of Electromagnetic Band Gap Structures with Suppressed Surface Waves Propagation
    (Společnost pro radioelektronické inženýrství, 2010-04) Kovacs, Peter; Raida, Zbynek
    The paper is focused on the automated design and optimization of electromagnetic band gap structures suppressing the propagation of surface waves. For the optimization, we use different global evolutionary algorithms like the genetic algorithm with the single-point crossover (GAs) and the multi-point (GAm) one, the differential evolution (DE) and particle swarm optimization (PSO). The algorithms are mutually compared in terms of convergence velocity and accuracy. The developed technique is universal (applicable for any unit cell geometry). The method is based on the dispersion diagram calculation in CST Microwave Studio (CST MWS) and optimization in Matlab. A design example of a mushroom structure with simultaneous electromagnetic band gap properties (EBG) and the artificial magnetic conductor ones (AMC) in the required frequency band is presented.
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    Feedback Compensation Algorithm for BPSK/QPSK Carrier Synchronization
    (Společnost pro radioelektronické inženýrství, 2010-04) Liu, Yinsheng; Tao, Cheng
    This paper deals with carrier synchronization problem in coherent communication system, such as BPSK and QPSK. First, this paper surveys and analyzes currently existing carrier synchronization algorithms and relevant receiver structures. After an analysis of those methods, a novel algorithm called feedback compensation is proposed, including the receiver structures based on this new synchronization algorithm. This new algorithm can not only simplify the signal processing stage but also decouple the demodulator and carrier synchronization module. At last, FPGA implementation results are presented and discussed.
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    Calculation and Comparison of Turbulence Attenuation by Different Methods
    (Společnost pro radioelektronické inženýrství, 2010-04) Dordova, Lucie; Wilfert, Otakar
    This paper is focused on the effect of turbulence in atmospheric transmission media. A short introduction of the origin of turbulent atmosphere is given. Two classical methods for the calculation of turbulence attenuation are mentioned and briefly described in the paper – the Rytov approximation and Andrews’s method, and a new technique designed by the authors of this paper – the method of available power – is presented in short as well. We have run simulations in Matlab to compare the results of turbulence attenuation given by the classical methods and by the new technique - the method of available power. These calculations were performed for communication wavelengths of 850 nm and 1550 nm. The distance between the optical transmitter and receiver of horizontal links was set to values ranging from 0 m to 2500 m. We have taken into account the homogenous turbulence with low (10^-16 m^-2/3), medium (10^-15 m^-2/3) and high (10^-14 m^-2/3) structure parameter of refractive index Cn2.