UKoLoS - ultra-wideband radio technologies for communications, localisation and sensor applications. - In: Frequenz, ISSN 0016-1136, Bd. 63 (2009), 9/10, S. 170-171
Algebraic norm-maximizing (ANOMAX) transmit strategy for two-way relaying with MIMO amplify and forward relays. - In: IEEE signal processing letters, ISSN 1558-2361, Bd. 16 (2009), 10, S. 909-912
https://doi.org/10.1109/LSP.2009.2026453
Ceramic microwave circuits for satellite communication. - In: Journal of microelectronics and electronic packaging, ISSN 1551-4897, Bd. 6 (2009), 1, S. 27-31
Experimental study of the effect of flux trapping on the operation of RSFQ circuits. - In: IEEE transactions on applied superconductivity, ISSN 1558-2515, Bd. 19 (2009), 3, S. 607-610
This paper investigates the robustness of different ground plane configurations of superconducting circuits against magnetic flux trapping. The robustness of the circuit is determined by the change of the error rate at a specific operating point under the influence of an external magnetic field. A large number of thermocycles are used to determine the statistic properties of the error rate. The proposed measurement setup allows a fast scan of a two-dimensional operating area.
https://doi.org/10.1109/TASC.2009.2018738
Impedance matching of microstrip inductors in digital superconductive electronics. - In: IEEE transactions on applied superconductivity, ISSN 1558-2515, Bd. 19 (2009), 3, S. 644-648
State-of-the-art RSFQ circuits consist of Josephson junctions, inductances and bias current sources, where the inductances are practically used as functional elements. Even more, their value defines the functionality and therefore the conventional design process requires strict conditions for the wiring between Josephson junctions. The present design and optimization process does not take into account their parasitic capacitances to ground. This becomes an important issue for ultra fast applications above 100 GHz, but also for circuits dedicated to control quantum electronics. We report on a theoretical and experimental investigation of the influence of ground capacitances. The impedance matching between the connecting microstrip lines and the Josephson junction is a key issue for the correct operation of these circuits. We performed circuit simulations and collected experimental data of correct and incorrect operating circuits to derive design criteria. The critical reflection coefficient is found to be 0.35 and the particular design must use a smaller value for transfer and a larger value for storage of SFQ pulses, respectively.
https://doi.org/10.1109/TASC.2009.2019284
Reduced probability of noise introduced malfunction in RSFQ circuits by implementing intrinsic [pi]-phaseshifter. - In: IEEE transactions on applied superconductivity, ISSN 1558-2515, Bd. 19 (2009), 3, S. 621-625
The Rapid Single Flux Quantum lectronics is characterized by a low switching energy, which makes it susceptible to noise introduced bit-errors. For industrial applications a certain noise immunity is required which is still a challenge especially for circuits of higher complexity.We analysed the influence of each individual resistor in a toggle Flip-Flop circuit to the overall bit-error rate. The shunt resistors of comparator structures are the dominant noise sources and bias resistors have almost no influence. Our theoretical analysis shows a significant impact of the phase offset caused by a pi-phaseshifter, which increases the robustness of RSFQ electronics even for circuits fabricated in mature Nb-technology. We experimentally investigated the influence of the pi-phaseshifter on the bit-error rate. We designed dedicated test circuits with and without a phaseshifter. There are only slight differences in the layout of both cells, thus it can be concluded that this advantage is based only on the influence of the phaseshifter. Our presented experiments show significant variances in the bit-error rate confirming the improved immunity against noise. Design and fabrication were performed by FLUXONICS Foundry.
https://doi.org/10.1109/TASC.2009.2018145
Cryogenic semiconductor amplifier for RSFQ-circuits with high data rates at 4.2 K. - In: IEEE transactions on applied superconductivity, ISSN 1558-2515, Bd. 19 (2009), 3, S. 574-579
The connection of RSFQ circuits with commercial room temperature electronics and amplifying SFQ pulses with high data rates require cryogenic interface amplifiers. Such amplifiers should provide extremely high bandwidth, low noise and low power consumption at the same time. Various hybrid amplifiers based on commercial p-HEMT transistors in an embedded microwave design were designed and characterized. Towards the p-HEMT transistor characterization at cryogenic temperature the biasing settings according to an optimum between voltage gain and low power consumption were determined. Thus a total power consumption of 2 mW and a voltage gain of 12 dB per single stage were achieved. For a preamplifier and an amplifier concept a multiple number of these stages were implemented in a microstrip and a coplanar transmission line design with a special matched interconnect taper towards the RSFQ components. Measurements of the amplifiers, the combination of an amplifier with a RSFQ circuit at 4.2 K showed their good performances without any disturbance of the RSFQ circuit. Due to the losses between the stages a total gain of 25 dB with a four stage amplifier was achieved; pulse rates went up to 3 Gb/s. The total power consumption was in the range of 8 mW. Further increase of data rates will be achieved by improving the matching between RSFQ output stage and amplifier.
https://doi.org/10.1109/TASC.2009.2018425
SVD-based precoding for single carrier MIMO transmission with frequency domain MMSE turbo equalization. - In: IEEE signal processing letters, ISSN 1558-2361, Bd. 16 (2009), 5, S. 418-421
https://doi.org/10.1109/LSP.2009.2016455
Single snapshot spatial smoothing with improved effective array aperture. - In: IEEE signal processing letters, ISSN 1558-2361, Bd. 16 (2009), 6, S. 505-508
https://doi.org/10.1109/LSP.2009.2017573
Wideband polarimetric directional propagation channel analysis inside an arched tunnel. - In: IEEE transactions on antennas and propagation, ISSN 1558-2221, Bd. 57 (2009), 3, S. 760-767
http://dx.doi.org/10.1109/TAP.2009.2013417