| 1. |
- Ferndahl, Mattias, 1973, et al.
(författare)
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A General Statistical Equivalent-Circuit-Based De-Embedding Procedure for High-Frequency Measurements
- 2008
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Ingår i: IEEE Transactions on Microwave Theory and Techniques. - 0018-9480 .- 1557-9670. ; 56:12, s. 2692-2700
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Tidskriftsartikel (refereegranskat)abstract
- A general equivalent-circuit-based method for the de-embedding of scattering parameters is presented. An equivalent circuit representation is used to model the embedding package. The parameters in the models are estimated with a statistical method using measured data from all de-embedding standards jointly together. Hence, it is possible to assess parameter estimates and their variance and covariance due to measurement uncertainties. A general de-embedding equation, which is valid for any five-port with a defined nodal admittance matrix, is derived and used in the subsequent de-embedding of measured device data. Different equivalent circuit models for the embedding network are then studied, and tradeoffs between model complexity and uncertainty are evaluated. Furthermore, the influence of varying number and combinations of de-embedding standards on the parameter estimates is investigated. The method is verified, using both measured and synthetic data, and compared against previously published work. It is found to be more general while keeping or improving accuracy.
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| 3. |
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| 4. |
- Kuylenstierna, Dan, 1976, et al.
(författare)
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Ultrawide-band tunable true-time delay lines using ferroelectric varactors
- 2005
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Ingår i: IEEE Transactions on Microwave Theory and Techniques. - 0018-9480 .- 1557-9670. ; 53:6, pt.2, s. 2164-70
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Tidskriftsartikel (refereegranskat)abstract
- This paper reports on compact tunable true-time delay lines based on ferroelectric (Ba/sub 0.25/Sr/sub 0.75/TiO/sub 3/) varactors integrated on high-resistivity silicon. The delay lines are based on lumped elements, physically implemented as synthetic coplanar-strip lines. An approximate analytical design procedure, exactly valid for omega to 0, is proposed. The physical size of the fabricated delay lines is 2.0*0.33 mm/sup 2/, including bias pads. Measurements are performed from room temperature (RT) down to 80 K. The measurements reveal ultrawide-band characteristics for both group delay and insertion loss. At RT, the absolute group delay is tau /sub delta /(RT, 0 V) approximately=70 ps with tunability of 20% under 20-V dc bias, the insertion less than 3.5 dB, and the reflection loss better than 12 dB below 20 GHz. At 145 K, the absolute group delay is increased to tau /sub delta /(145 K, 0 V) approximately=100 ps with a tunability of 50% under 20-V applied bias. At 7 GHz, the insertion loss is 3 dB, resulting in figures-of-merit of 0.03 dB/ps and 50 ps/mm. The leakage current at RT is less than 0.1 mu A
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| 5. |
- Rafique, Raihan, 1978, et al.
(författare)
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Miniaturization of superconducting passive filters for on-chip applications
- 2007
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Ingår i: 11th International Superconducting Electronics Conference, Washington DC, USA, June 10-14, 2007.. ; 11, s. P-V09
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- We present techniques to miniaturize superconducting ultra narrowband filters for on-chip applications. The filters are designed for 2 GHz, 5 GHz and 10 GHz operating frequencies. The expected bandwidths of the designed filters are 2-20 MHz. The designs are of 7 stages Chebyshev filters having maximum passband ripples of 0.5 dB. On-chip filters are particularly interesting as they are applicable for monolithic design with the RSFQ circuit aiming qubit applications. One of the designs is a quasi-lumped filter where the effective wave propagation constant has been increased by the addition of lumped components to the superconducting microstrip line (SMSL). Additionally, this design provides the optimum width of an SMSL without violating design rules. The other design consists of distributed and lumped components. The area of the filter is in the range of 1-2 square mm. We present the filter topologies and corresponding experimental results for the frequency response of these on-chip filters designed for Hypres 4.5 kA/cm2 fabrication process.
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| 6. |
- Rafique, Raihan, 1978, et al.
(författare)
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Miniaturized superconducting microwave filters
- 2008
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Ingår i: Superconducting Science and technology, press.
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Tidskriftsartikel (refereegranskat)abstract
- In this paper we present methods for miniaturization of superconducting filters. We consider two designs of 7th order bandpass Chebyshev filters based on lumped elements and a novel quasi-lumped element resonators. In both designs the area of the filters, with a central frequency of 2-5 GHz, is less than 1.2 mm2. Such small filters can be readily integrated on one board for multi-channel microwave control of superconducting qubits. The filters have been experimentally tested and the results are compared with simulations. The miniaturization resulted in parasitic coupling between resonators and within eachresonator that affected primarily stopband and bandwidth increase. The severity of the error depends on the design in particular, and was less prawn when groundplane was used under the inductances of the resonators. The best performance was reached for the quasi-lumped filter with central frequency of 4.5 GHz, quality factor of 100 and 28 dB stopband.
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| 7. |
- Rafique, Raihan, 1978, et al.
(författare)
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Niobium Tunable Microwave Filter
- 2009
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Ingår i: IEEE Transactions on Microwave Theory and Techniques. - 0018-9480 .- 1557-9670. ; 57:5, s. 1173-1179
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Tidskriftsartikel (refereegranskat)abstract
- A superconductor bandpass filter with tunable centralfrequency in the range of 2.1–3.5 GHz has been implementedusing Superconducting Quantum Interference Devices (SQUID).The filter is designed as two pi–network resonators connected by a transmission line. Both resonators have a SQUID inductor with a tuning range of 65–200 pH, controlled by DC current magnetically coupled to the SQUIDs. Over a frequency tunability of 40% from 3.5 to 2.1 GHz, the filter has a corresponding fractional bandwidth of 35% to 27% and a mid-band insertion loss of 0.5–3.0 dB. Due to the presence of active elements, the tunability of the filter depends on the power of the microwave signal. A maximum power of -52dBm corresponds to a frequency tuning range of 15%. Spectral measurements by controlling the central frequency of the filter with variable pulse-width shows that the filter can be tuned at a rate of 120 GHz per us.
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| 9. |
- Rafique, Raihan, 1978, et al.
(författare)
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Tunable Impedance Matching Network
- 2008
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Ingår i: GigaHertz Symposium, March, 2008. ; , s. 15-
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Konferensbidrag (refereegranskat)abstract
- We present superconducting SQUID based tunableimpedance matching networks designed for highly miniaturized filters. The performance of miniaturized filters is very sensitive to parasitic and fabrication related spread. The presented experimental results show that using tunable impedance matching networks, the degraded performances of these types of filters isimproved.
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| 10. |
- Zeng, Xuezhi, 1980, et al.
(författare)
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Accuracy evaluation of time domain measurement systems for microwave tomography
- 2009
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Ingår i: IEEE MTT-S International Microwave Symposium Digest. - 0149-645X. - 9781424428045 ; , s. 1441-1444
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Konferensbidrag (refereegranskat)abstract
- The measurement accuracy of time domain systemsfor microwave tomography are evaluated through system levelsimulations and compared with that of a network analyzerbased frequency domain system. In the analysis, both a timedomain ultra-wideband (UWB) impulse and multiband systemarchitectures are considered. It is shown that the measurementerror of the time domain systems mainly comes from analogto digital (A/D) conversion. For a simple comparison case, therelative measurement error involved in an estimated objectresponse signal from the time domain UWB impulse system andUWB multiband system measurements are around three timesand ten times higher than that from frequency domain system.
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