Attila Zolomy

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Automatic antenna tuning circuitry is presented for high Q printed antennas. It is applied in a general purpose 0.6 /spl mu/m BiCMOS transmitter chip devoted to short range applications in the ISM bands (315, 434, 868 and 915 MHz). The circuitry maintains maximum output power without the application of external matching circuit and/or costly tuning(More)
In this paper design a method is presented for broadband matching of complex impedances using distributed circuit elements. The method is a combination of the classical analytic network theory approach for lumped element matching networks and of the numerical optimization techniques. The aim is to create distributed element matching networks for Rf(More)
This paper introduces a novel approach for transmitting UWB signals over optical fibre with cost effective Vertical-cavity surface-emitting laser (VCSEL). The transmitted impulse compile with the strict European frequency plan (ECC). A prototype filter is presented with lumped elements which has a −40 dB/500 MHz cut off at the critical 3.1 GHz band.(More)
In case of integrated digital radio chips devoted to low cost, licence free short range radio systems the necessary bill of material and the battery life are one of the most important issues. The targeted RF power level determines whether a low or a high Q output architecture (output driver stage+optional matching+antenna) gives better result. It is shown(More)
Input-reduced noise current density of a distributed amplifier excited by a photodiode is minimised. It has been found that for low noise the admittance of the transmission line between the amplifier and the pin photodiode has to be small. To prove this statement we have obtained an analytical formula for the input-reduced noise current density of the(More)
The quantum based communication techniques are one of the leading research topics of optical communication. Quantum based Free-Space Optical (FSO) communication systems are potential alternatives to high speed microwave communication. The high speed operation requires wide operation bandwidth for the elements applied in the FSO link including the(More)
It is shown that distributed amplifiers using transmission lines between the active devices are able to operate at higher order passbands. This feature is similar to the operation of a distributed element microwave filters, where besides the fundamental, higher order passbands appear at the odd harmonics. This property allows higher frequency operation(More)
Worldwide application of wireless IoT and telemetry solutions are more cost effective if they are inherently able to operate in multiple frequency bands as these units require lower logistics and manufacturing cost. Moreover, interferences in the highly crowded available frequency bands enhances the advantages of multiband operation wireless system.(More)
Calculations are presented to study the phase noise suppression effects of an additionally introduced highly nonlinear feedback loop in microwave harmonic oscillators. Calculations are done for determining the optimal structure and parameter set of nonlinearly feedbacked harmonic oscillators, with respect to the effects of the nonlinear properties on the(More)
In this paper the investigations of the parasitics in a fabricated X-band tuneable metamaterial isolator are presented. The isolator applies a microstrip left handed artificial transmission line (LHTL) with Butterworth phase response on an anisotropic ferrite substrate material. The structure is simplified and optimized to reduce the harmful right handed(More)