Flores J.L.,AT4 Wireless
Microwave Journal | Year: 2010
A new method for mixer spurs calculation, which has been found easier and more straightforward to use than the traditional spurs chart approach when dealing with the frequency plan optimization in broadband double conversion transceivers suitable for applications as multiband, multi standard and Software Defined Radio (SDR) is discussed. Regardless of the output spectrum component levels in a particular frequency conversion, their frequency values can be obtained in a much more generic way. The maximum pass band for the RF filter will be determined by its guard value selected and the IMP allowed in the IF band. The Distances Chart is a new method to find mixer spurs, allowing for an easy optimization of the IF and RF filter bands as well as the LO sweep band in applications where a broad frequency band with wide IF is to be covered, as in the case of broadband double conversion transceivers for multiband, multi standard and SDR applications. This method is easier and more straightforward to use than the traditional spurs chart approach during the study phase of such converters.
Lopez-Berrocal B.,AT4 Wireless |
De-Oliva-Rubio J.,University of Malaga |
Molina-Fernandez I.,University of Malaga |
Montejo-Garai J.R.,University of Malaga
International Journal of RF and Microwave Computer-Aided Engineering | Year: 2014
This article presents a simple topology for the implementation of cross-couplings between nonadjacent resonators in interdigital stripline filters. This topology affords the inclusion of transmission zeros maintaining a cross-sectional structure similar to that of a stripline. Therefore, the manufacturing cost is very close to an all-pole prototype. Two design strategies for the coupling structure are discussed: one of them achieving filters with enhanced performance. Both strategies have been assessed implementing prototypes in low-temperature cofired ceramic (LTCC) technology. The fabricated filters exhibit operating frequencies at 5775 MHz and 8000 MHz with 2.6% and 3.75% pass-band fractional bandwidths, respectively, and up to 60 dB IL in the rejection band. © 2014 Wiley Periodicals, Inc.
Perez-Lara P.,AT4 Wireless |
Molina-Fernandez I.,University of Malaga |
Wanguemert-Perez J.G.,University of Malaga |
Rueda-Perez A.,University of Malaga
IEEE Transactions on Microwave Theory and Techniques | Year: 2010
A simple five-port direct receiver achieving broadband performance and high local oscillator to RF isolation is presented. The new circuit comprises three power detectors exhibiting high series impedance, four resistors, and two low-pass and two high-pass phase shifters. It is shown that the phase-shift networks can be designed to optimize receiver operation over a theoretical decade bandwidth. A 300-MHz2.7-GHz prototype is built and measured to prove feasibility of this proposal. © 2006 IEEE.
Witrisal K.,University of Graz |
Pausini M.,AT4 Wireless
Proceedings of the 5th European Conference on Antennas and Propagation, EUCAP 2011 | Year: 2011
A statistical characterization is presented of the impact of the ultra-wideband (UWB) multipath channel on impulse radio and spread-spectrum UWB systems. For this purpose, the correlator output statistics are studied, since correlators are the typical first processing step in the frontends of coherent and noncoherent receivers. The analysis is based on the second and forth-order moments of the channel impulse response. It also includes a prototype pulse shape that represents the bandwidth of the received pulse and all linear system components including antenna effects. Complex-equivalent baseband representations of UWB pulses are assumed, which makes the analysis suitable for investigating bandpass-type UWB systems as defined in various IEEE standards. The analytical results are validated through the analysis of measured UWB channels. © 2011 EurAAP.
Oya J.R.G.,University of Seville |
Munoz F.,University of Seville |
Torralba A.,University of Seville |
Jurado A.,AT4 Wireless |
And 2 more authors.
IEEE Transactions on Instrumentation and Measurement | Year: 2012
This paper presents the implementation of a data acquisition system, where the folded thermal noise is reduced by using two consecutive subsampling processes. The presented implementation is used to test wideband multistandard receivers covering most of present communication standards. The proposed system converts a 20-MHz signal modulated with a programmable carrier frequency up to 6.5 GHz, so that it could be used as a universal receiver for software-defined radio applications. Experimental results show an effective number of bits larger than 9 bits up to 2.9 GHz, 8 bits up to 6.5 GHz, and 6.4 bits up to 20 GHz of input carrier frequency. © 1963-2012 IEEE.