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38 results on '"Sarkozy, S."'

1. On the Zero-Bias Anomaly in Quantum Wires

Author

Sarkozy, S., Sfigakis, F., Gupta, K. Das, Farrer, I., Ritchie, D. A., Jones, G. A. C., and Pepper, M.

Subjects
Condensed Matter - Mesoscale and Nanoscale Physics, Condensed Matter - Strongly Correlated Electrons
Abstract

Undoped GaAs/AlGaAs heterostructures have been used to fabricate quantum wires in which the average impurity separation is greater than the device size. We compare the behavior of the Zero-Bias Anomaly against predictions from Kondo and spin polarization models. Both theories display shortcomings, the most dramatic of which are the linear electron-density dependence of the Zero-Bias Anomaly spin-splitting at fixed magnetic field B and the suppression of the Zeeman effect at pinch-off.

Published
2008
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2. Low Temperature Transport in Undoped Mesoscopic Structures

Author

Sarkozy, S., Gupta, K. Das, Siegert, C., Ghosh, A., Pepper, M., Farrer, I., Beere, H. E., Ritchie, D. A., and Jones, G. A. C.

Subjects
Condensed Matter - Mesoscale and Nanoscale Physics
Abstract

Using high quality undoped GaAs/AlGaAs heterostructures with optically patterned insulation between two layers of gates, it is possible to investigate very low density mesoscopic regions where the number of impurities is well quantified. Signature appearances of the scattering length scale arise in confined two dimensional regions, where the zero-bias anomaly (ZBA) is also observed. These results explicitly outline the molecular beam epitaxy growth parameters necessary to obtain ultra low density large two dimensional regions as well as clean reproducible mesoscopic devices., Comment: 4 pages, 4 EPS figs

Published
2008
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4. W-band Heterodyne Receiver Module with 27 K Noise Temperature

Author

Gawande, R, Reeves, R, Cleary, K, Readhead, A. C, Gaier, T, Kangaslahti, P, Samoska, L, Church, S, Sieth, M, Voll, P, Harris, A, Lai, R, and Sarkozy, S

Subjects
Electronics And Electrical Engineering
Abstract

We present noise temperature and gain measurements of a W-band heterodyne module populated with MMIC LNAs designed and fabricated using 35nm InP HEMT process. The module has a WR-10 waveguide input. GPPO connectors are used for the LO input and the I and and Q IF outputs. The module is tested at both ambient (300 K) and cryogenic (25 K) temperatures. At 25 K physical temperature, the module has a noise temperature in the range of 27-45 K over the frequency band of 75-111 GHz. The module gain varies between 15 dB and 27 dB. The band-averaged module noise temperature of 350 K and 33 K were measured over 80-110 GHz for the physical temperature of 300 K and 25 K, respectively. The resulting cooling factor is 10.6.

Published
2012

5. An MMIC low-noise amplifier design technique

Author

Varonen, M., Reeves, R., Kangaslahti, P., Samoska, L., Cleary, K., Akgiray, A., Gawande, R., Fung, A., Gaier, T., Weinreb, S., Readhead, A. C. S., Lawrence, C., Sarkozy, S., Lai, R., Varonen, M., Reeves, R., Kangaslahti, P., Samoska, L., Cleary, K., Akgiray, A., Gawande, R., Fung, A., Gaier, T., Weinreb, S., Readhead, A. C. S., Lawrence, C., Sarkozy, S., and Lai, R.

Abstract

In this paper we propose a parallel two-finger unit transistor MMIC low-noise amplifier design technique which enables the design of wideband and high linearity low-noise amplifiers with very stable, predictable, and repeatable operation. We prove the feasibility of the proposed design technique by demonstrating a three-stage LNA packaged in a WR10 waveguide housing and fabricated using a 35-nm InP HEMT technology that achieves more than a 20-dB gain from 75 to 116 GHz and 26–33-K noise temperature from 85 to 116 GHz when cryogenically cooled to 27 K.

Published
2015

6. An MMIC low-noise amplifier design technique

Author

Varonen, M., primary, Reeves, R., additional, Kangaslahti, P., additional, Samoska, L., additional, Cleary, K., additional, Akgiray, A., additional, Gawande, R., additional, Fung, A., additional, Gaier, T., additional, Weinreb, S., additional, Readhead, A. C. S., additional, Lawrence, C., additional, Sarkozy, S., additional, and Lai, R., additional

Published
2015
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7. Cryogenic Probing of mm-Wave MMIC LNAs for Large Focal-Plane Arrays in Radio-Astronomy

Author

Reeves, R., Cleary, K., Gawande, R., Kooi, J., Lamb, J., Readhead, A., Weinreb, S., Gaier, T., Kangaslahti, P., Russell, D., Samoska, L., Varonen, M., Lai, R., Sarkozy, S., Reeves, R., Cleary, K., Gawande, R., Kooi, J., Lamb, J., Readhead, A., Weinreb, S., Gaier, T., Kangaslahti, P., Russell, D., Samoska, L., Varonen, M., Lai, R., and Sarkozy, S.

Abstract

In this paper, we demonstrate non-destructive cryogenic probing of monolithic microwave integrated circuit (MMIC) amplifiers at W-band and discuss the implications for the development of large-format focal plane arrays for radio astronomy. Using a purpose-built cryogenic probe station to measure S-parameters and noise temperature of MMIC low-noise amplifiers (LNAs), an order of magnitude increase in efficiency can be achieved when compared with measurements on individually packaged amplifiers. The amplifiers are tested non-destructively, which enables selection based on cryogenic noise and gain; this is crucial for the development of highly-integrated miniaturized receivers for focal plane arrays, such as those used for the measurement of the cosmic microwave background (CMB) polarization and future arrays aimed at probing the epoch of reionization (EoR).

Published
2014

10. A W-band heterodyne receiver module prototype for focal plane arrays

Author

Gawande, R., primary, Reeves, R., additional, Cleary, K., additional, Kooi, J., additional, Readhead, A. C., additional, Gaier, T., additional, Kangaslahti, P., additional, Samoska, L., additional, Varonen, M., additional, Church, S., additional, Devaraj, K., additional, Sieth, M., additional, Voll, P., additional, Harris, A., additional, Lai, R., additional, and Sarkozy, S., additional

Published
2014
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11. W-Band cryogenic InP MMIC LNAs with noise below 30K

Author

Samoska, L., Varonen, M., Reeves, R., Cleary, K., Gawande, R., Kangaslahti, P., Gaier, T., Lai, R., Sarkozy, S., Samoska, L., Varonen, M., Reeves, R., Cleary, K., Gawande, R., Kangaslahti, P., Gaier, T., Lai, R., and Sarkozy, S.

Abstract

In this paper, we describe two monolithic millimeter-wave integrated circuit (MMIC) low noise amplifiers (LNAs) for W-Band which have a noise temperature of 30K or better over a wide bandwidth when cryogenically cooled. The LNAs were designed and fabricated in NGC's InP HEMT MMIC process having 35 nm gate length and employing an InAs Composite Channel (IACC). A two-stage amplifier exhibits room temperature S21 gain of 15–18 dB, and cryogenic gain of 20 dB with minimum noise temperature of 25K at 95 GHz, and less than 40K noise temperature between 75–105 GHz. A three-stage amplifier exhibits 29 dB of S21 gain, and a cryogenic noise temperature below 30K over the range of 94–109 GHz. We discuss the design of the amplifiers, measured and simulated S-parameters, and cryogenic measurements. To our knowledge, these are the highest frequency and lowest noise temperatures ever reported for InP cryogenic LNAs covering W-Band.

Published
2012

12. W-band heterodyne receiver module with 27 K noise temperature

Author

Gawande, R., Reeves, R., Cleary, K., Readhead, A. C., Gaier, T., Kangaslahti, P., Samoska, L., Church, S., Sieth, M., Voll, P., Harris, A., Lai, R., Sarkozy, S., Gawande, R., Reeves, R., Cleary, K., Readhead, A. C., Gaier, T., Kangaslahti, P., Samoska, L., Church, S., Sieth, M., Voll, P., Harris, A., Lai, R., and Sarkozy, S.

Abstract

We present noise temperature and gain measurements of a W-band heterodyne module populated with MMIC LNAs designed and fabricated using a 35 nm InP HEMT process. The module has a WR-10 waveguide input. GPPO connectors are used for the LO input and the I and Q IF outputs. The module is tested at both ambient (300 K) and cryogenic (25 K) temperatures. At 25 K physical temperature, the module has a noise temperature in the range of 27–45 K over the frequency band of 75–111 GHz. The module gain varies between 15 dB and 27 dB. The band-averaged module noise temperature of 350 K and 33 K were measured over 80–110 GHz for the physical temperature of 300 K and 25 K, respectively. The resulting cooling factor is 10.6.

Published
2012

17. W-band heterodyne receiver module with 27 K noise temperature

Author

Gawande, R., primary, Reeves, R., additional, Cleary, K., additional, Readhead, A. C., additional, Gaier, T., additional, Kangaslahti, P., additional, Samoska, L., additional, Church, S., additional, Sieth, M., additional, Voll, P., additional, Harris, A., additional, Lai, R., additional, and Sarkozy, S., additional

Published
2012
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20. Low Noise Amplification at 0.67 THz Using 30 nm InP HEMTs

Author

Deal, William. R., primary, Leong, K., additional, Radisic, V., additional, Sarkozy, S., additional, Gorospe, B., additional, Lee, J., additional, Liu, P. H., additional, Yoshida, W., additional, Zhou, J., additional, Lange, M., additional, Lai, R., additional, and Mei, X. B., additional

Published
2011
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26. A 50 mW 220 GHz power amplifier module

Author

Radisic, V., primary, Leong, K. M., additional, Mei, X., additional, Sarkozy, S., additional, Yoshida, W., additional, Liu, P., additional, Uyeda, J., additional, Lai, R., additional, and Deal, W. R., additional

Published
2010
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28. Zero-bias anomaly in quantum wires

Author

Sarkozy, S., primary, Sfigakis, F., additional, Das Gupta, K., additional, Farrer, I., additional, Ritchie, D. A., additional, Jones, G. A. C., additional, and Pepper, M., additional

Published
2009
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38. Clinical chronobiology and chronome-geriatrics at variance with recommendations of subsequent guidelines, yet focusing indeed on pre-hypertension in the physiological range.

Author

Otsuka K, Cornélissen G, Schwartzkopff O, Bakken EE, Halberg F, Burioka N, Katinas GS, Kane R, Regal PJ, Schaffer E, Sonkowsky R, Patterson R, Engebretson M, Brockway B, Wang Z, Delmore P, Halpin C, Sarkozy S, Wall D, and Halberg J

Subjects
Blood Pressure Determination methods, Blood Pressure Determination trends, Humans, Hypertension diagnosis, Aging physiology, Chronobiology Phenomena physiology, Guidelines as Topic, Hypertension physiopathology
Published
2003
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