2010/1

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Recent Submissions

Now showing 1 - 5 of 31
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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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    New Channel Coding Methods for Satellite Communication
    (Společnost pro radioelektronické inženýrství, 2010-04) Rumanek, Jaroslav; Sebesta, Jiri
    This paper deals with the new progressive channel coding methods for short message transmission via satellite transponder using predetermined length of frame. The key benefits of this contribution are modification and implementation of a new turbo code and utilization of unique features with applications of methods for bit error rate estimation and algorithm for output message reconstruction. The mentioned methods allow an error free communication with very low Eb/N0 ratio and they have been adopted for satellite communication, however they can be applied for other systems working with very low Eb/N0 ratio.
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    Multicriteria Optimization of Antennas in Time-Domain
    (Společnost pro radioelektronické inženýrství, 2010-04) Lacik, Jaroslav; Lager, Ioan E.; Raida, Zbynek
    An original approach to the time-domain multicriteria optimization of antennas is presented. For a given excitation pulse, the time-domain objective function takes the “time-domain impedance matching”, distortion of responses at the feeding point and in a desired radiating direction (with respect to the excitation pulse), and the radiated energy in the desired direction into account. The objective function is tested on the optimization of a bow-tie antenna using the particle swarm optimization. The proposed approach is suitable for the design of broadband antennas.
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    Circularly Polarized Aperture Coupled Microstrip Antenna with Resonant Slots and a Screen
    (Společnost pro radioelektronické inženýrství, 2010-04) Kirov, Georgi S.; Mihaylova, Desislava P.
    A broadband circularly polarized (CP) Aperture Coupled Microstrip Antenna (ACMSA) is described herein. In order to decrease the back radiation of the antenna due to resonant coupling slots (a cross-slot) in the ground plane, a three-layer structure with a screen is proposed. As a result, the back radiation of the antenna is reduced by more than 12 dB and its gain is increased by about 1.3 dB compared to the conventional two-layer ACMSA with nonresonant coupling slots. The antenna is designed to operate within the Ku-band. Keeping its simple and compact construction and high mechanical characteristics it can be used as an element of CP microstrip antenna arrays with various applications in the contemporary communication systems. A comparison with two similar CP antennas with resonant slots, a two-layer ACMSA and a three-layer ACMSA with a patch reflector is accomplished.