ULTRA-LOW-NOISE, InP FIELD EFFECT TRANSISTOR RADIO ASTRONOMY RECEIVERS: STATE-OF-THE-ART
Marian W. Pospieszalski
National Radio Astronomy Observatory
Date: Wednesday April 11th, 2012
Time: 5:30 Reception, Dinner (Optional) 6:00 pm, Lecture 7:00
Place: Mitre Building 2
All IEEE members and guests are welcome to attend.
Cost: Lecture and reception free, Dinner $15
Please RSVP to Roger Kaul, 301-394-4775 or email@example.com by April 9th
In the early 1970's, the ultra-low-noise receiving systems employed mainly solid-state masers, cryogenically-cooled parametric amplifiers (or converters) and Schottky diode mixers. At the end of that decade, advances in GaAs FET technology, combined with cryogenic cooling, made the noise performance of GaAs FET amplifiers competitive with the noise performance of parametric amplifiers and masers. Indeed, improvements in the noise temperature of field-effect transistors (FET’s) and, later, heterostructure field-effect transistors (HFET’s) over the last several decades have been quite dramatic. In 1970, a noise temperature of 120 K was reported at 1 GHz and physical temperature of 77 K; in 2003, noise temperatures of 2, 8 and at 35 K were reported at 4, 30 and 100 GHz, respectively, for physical temperatures of 14 to 20 K. These last results were achieved with InP HFETs. Broadband amplifiers using these devices have been successfully used in a number of instruments for radio astronomy research. These include: Very Large Array (VLA), Very Large Baseline Array (VLBA), Green Bank Telescope (GBT), Wilkinson Microwave Anisotropy Probe (MAP), Planck Low Frequency Instrument and several ground-based instruments for the investigation of cosmic microwave background. Against this background, the presentation will focus on the following main topics:
In conclusion, thoughts on future developments in
low-noise amplifier technology will be offered. Especially a question whether rapidly
advancing technologies of microwave heterostucture bipolar transistors (HBT’s)
and CMOS can in the future offer alternatives to the extremely low noise
performance of InP HFET’s will be addressed.
Noise models of microwave transistors and their general properties common to all field effect (FET) and bipolar transistors (BT)
Noise and signal properties of InP heterostructure field effect transistors (HFETs) at cryogenic temperatures
Design and examples of realizations of wideband, low-noise, cryogenically-coolable HFET amplifiers in 1 to 115 GHz range
Examples of realizations of receivers for interferometric arrays
Examples of realization of very broadband continuum radiometers
Marian W. Pospieszalski was awarded
the M.Sc. and D.Sc. degrees in electrical engineering from the Warsaw Institute
to 1984, Dr. Pospieszalski was with the
At NRAO, Dr. Pospieszalski has been involved with the theory and design of low-noise devices, amplifiers, and receivers with emphasis on the properties of field-effect transistors (FETs) at cryogenic temperatures. This work has resulted in the lowest noise HFET amplifiers and receivers ever reported in the 1 to 120 GHz range.
Dr. Pospieszalski has authored or co-authored over ninety journal and conference papers. He has been a member of the IEEE Transaction on Microwave Theory and Techniques (MTT) Editorial Board since 1987, and a member of the IEEE MTT Society Technical Committee on Microwave Low-Noise Techniques since 1992, serving as Chair of that Committee from 2001-2004. Also, he has been a member of the Technical Program Committee of the International Microwave Symposium since 1992, a member of URSI Commissions D and J and has served as a reviewer for many journals.
In 1977, Dr. Pospieszalski received
the Award of
Minister of Science, Technology and Higher Education (