10 research outputs found

    A simple NWA calibration algorithm based on a transfer standard

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    A new two-port network analyzer (NWA) calibration technique is here presented. It uses a single two-port transfer standard plus a known reflectance to perform the calibration process. The transfer standard device has to be previously fully characterized with a traceable NWA. The technique here proposed uses less standards than any other up today calibration algorithm, which, on the contrary, requires at least three different devices. The paper presents the calibration algorithm along with some on-wafer experimental results which compare the new solution with a more traditional technique

    A new approach to the design of wide-band multiprobe reflectometers

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    A new design approach for low-cost multiprobe reflectometers is presented. While traditional circuits adopt equally-spaced probes, the presented solution provide a method to greatly enhance the bandwidth of the measuring system by a proper choice of each probe position. As example, a five-probe 0.6-16 GHz system has been designed

    Testing devices under different source impedances: a novel technique for on-line measurement of source and device reflection coefficients

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    This paper describes a new approach for fast and accurate determination of the source reflection coefficient in microwave source-pull measurements. To the authors' knowledge, this is the only technique that allows the simultaneous measurement of the source and the DUT gammas. A traditional vector network analyzer is used as a three-channel receiver. The calibration procedure is based on a new reflectometer model that extends the traditional error box concept. Experimental results are presented and compared to data obtained with traditional techniques

    Load pull techniques for millimetre wave device characterisation

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    Load-pull experimental characterisation of active devices under non linear operation is a well proved technique still used in designing power amplifiers. When applied to the MMIC, this technique shall require special solutions to be extended to on-wafer devices up to millimetre waves. The paper presents an overview on the traditional load pull measurement techniques focusing the attention on millimetre wave application. An example of a fully automatic on-wafer system is described along with the more useful calibration techniques. By means of this test set a very detailed characterisation of devices can be carried out in short time, by setting the loads either at the fundamental or at the harmonic frequencies with independent controls.[Abstract

    A 3V small chip size GSM HBT power MMIC with 56% PAE

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    A three stage 56% power added efficiency (PAE) InGaP/GaAs HBT power MMIC for use in GSM applications (900MHz) is described. An output power of 2.7W is obtained at the connectors of the evaluation board with a single supply voltage of 3.2V. The large signal gain is in excess of 32dB and the dynamic range for power control exceeds 80 dB. The chip size of only 2mm² allows housing in a tiny plastic package (TSSOP10) which occupies less than one half of the board area compared to packaged GSM devices before. For circuit design an accurate electrothermal large-signal HBT model is used. For characterisation of large emitter area power transistors on-wafer large signal measurement techniques have been developed which assist model verification and provide new insights in the influence of harmonic load terminations. The design techniques employs two steps. In a first step on-wafer loadpull measurements provide reasonable conditions for output power, which are combined with appropriate small-signal simulations to fix th circuit topology in principal. In a second step refinements of the power performance are achieved by large-signal simulations

    Protocol and descriptive epidemiology of the SIGASCOT Italian multicentric registry of revision ACL reconstruction: A 1-year pilot study

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    The aim of the present study was to present the demographic and baseline results of the first year of course of the SIGASCOT Italian registry of Revision ACL reconstruction.The data of the patients undergoing revision ACL reconstruction, enrolled in by 20 SIGASCOT members from March 2015 to May 2016, were extracted from the Surgical Outcome System (SOS). Overall, 126 patients were enrolled; 18 were excluded due to incomplete data. Mean age at surgery was 30.4 +/- 9.3 years (median 29; 23-38), mean BMI was 22.6 +/- 2.3 kg/m2 and 77% were males. Revision was performed with a single-bundle technique in 94%, using allograft in 57% of cases and autograft in 43%. Only 28% had both menisci intact, and meniscal repair or replacement was performed in 25% of patients for medial meniscus and 8% for lateral meniscus. During the first year of enrollment, the SIGASCOT Italian ACL revision registry was able to collect the data of more than 100 patients. The revision ACL reconstruction was usually performed with a single-bundle technique, using allograft and autograft almost in the same exten

    Italian consensus statement for the use of allografts in ACL reconstructive surgery

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    Purpose: Graft choice for primary anterior cruciate ligament reconstruction (ACL-R) is debated, with considerable controversy and variability among surgeons. Autograft tendons are actually the most used grafts for primary surgery; however, allografts have been used in greater frequency for both primary and revision ACL surgery over the past decade. Given the great debate on the use of allografts in ACL-R, the \u201cAllografts for Anterior Cruciate Ligament Reconstruction\u201d consensus statement was developed among orthopedic surgeons and members of SIGASCOT (Societ\ue0 Italiana del Ginocchio, Artroscopia, Sport, Cartilagine, Tecnologie Ortopediche), with extensive experience in ACL-R, to investigate their habits in the use of allograft in different clinical situations. The results of this consensus statement will serve as benchmark information for future research and will help surgeons to facilitate the clinical decision making. Methods: In March 2017, a formal consensus process was developed using a modified Delphi technique method, involving a steering group (9 participants), a rating group (28 participants) and a peer-review group (31 participants). Nine statements were generated and then debated during a SIGASCOT consensus meeting. A manuscript has been then developed to report methodology and results of the consensus process and finally approved by all steering group members. Results: A different level of consensus has been reached among the topics selected. Strong agreement has been reported in considering harvesting, treatment and conservation methods relevant for clinical results, and in considering biological integration longer in allograft compared to autograft. Relative agreement has been reported in using allograft as the first-line graft for revision ACL-R, in considering biological integration a crucial aspect for rehabilitation protocol set-up, and in recommending a delayed return to sport when using allograft. Relative disagreement has been reported in using allograft as the first-line graft for primary ACL-R in patients over 50, and in not considering clinical results of allograft superior to autograft. Strong disagreement has been reported in using allograft as the first-line graft for primary ACL-R and for skeletally immature patients. Conclusions: Results of this consensus do not represent a guideline for surgeons, but could be used as starting point for an international discussion on use of allografts in ACL-R. Level of evidence: IV, consensus of experts