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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    Modeling of the Phase Noise in Space Communication Systems
    (Společnost pro radioelektronické inženýrství, 2010-04) Baran, Ondrej; Kasal, Miroslav
    Our work is focused on the investigation of an influence of an additive thermal noise and a multiplicative phase noise in space communication chains. The most important properties of both noise types are summarized. The main concern of this paper is on the multiplicative phase noise that is especially important in systems with the phase shift keying. The simulation procedure for modeling of a signal degraded by the multiplicative phase noise is described. One starts from the frequency domain, where noise properties are set up. Five basic phase noise types can be included. After a passing to the time domain, the final noisy signal is obtained. To prove the modeling correctness, two ways are used. Firstly, Allan variances are utilized as a time domain processing. Finally, for a comparison, the direct conversion formula from the frequency to the time domain is exploited. Created signal corrupted by the phase noise expresses the harmonic oscillator output signal. A pair of these oscillators, disturbed by different phase noise processes, is installed into a communication channel model and with its help, the simultaneous influence of both oscillators on the useful signal is examined. Results show a good coincidence with theoretical presumptions.
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    A Terrestrial Multiple-Receiver Radio Link Experiment at 10.7 GHz - Comparisons of Results with Parabolic Equation Calculations
    (Společnost pro radioelektronické inženýrství, 2010-04) Valtr, Pavel; Pechac, Pavel; Kvicera, Vaclav; Grabner, Martin
    This work presents the results of a terrestrial multiple-receiver radio link experiment at 10.7 GHz. Results are shown in the form of the power levels recorded at several antennas attached to a receiving mast. Comparisons of the measurement data with theoretical predictions using a parabolic equation technique show that, due to the complex propagation environment of the troposphere in terms of the refractive index of air, closer agreement between measurements and simulations can be achieved during periods of standard refractive conditions.