285 research outputs found
Design of Cryogenic SiGe Low-Noise Amplifiers
This paper describes a method for designing cryogenic silicon-germanium (SiGe) transistor low-noise amplifiers and reports record microwave noise temperature, i.e., 2 K, measured at the module connector interface with a 50-Ω generator. A theory for the relevant noise sources in the transistor is derived from first principles to give the minimum possible noise temperature and optimum generator impedance in terms of dc measured current gain and transconductance. These measured dc quantities are then reported for an IBM SiGe BiCMOS-8HP transistor at temperatures from 295 to 15 K. The measured and modeled noise and gain for both a single- and two-transistor cascode amplifier in the 0.2-3-GHz range are then presented. The noise model is then combined with the transistor equivalent-circuit elements in a circuit simulator and the noise in the frequency range up to 20 GHz is compared with that of a typical InP HEMT
A 0.1–5 GHz Cryogenic SiGe MMIC LNA
In this letter, the design and measurement of the first SiGe integrated-circuit LNA specifically designed for operation at cryogenic temperatures is presented. At room temperature, the circuit provides greater than 25.8 dB of gain with an average noise temperature (T_e) of 76 K (NF = 1 dB) and S11 of -9 dB for frequencies in the 0.1-5 GHz band. At 15 K, the amplifier has greater than 29.6 dB of gain with an average Te of 4.3 K and S11 of -14.6 dB for frequencies in the 0.1-5 GHz range. To the authors' knowledge, this is the lowest noise ever reported for a silicon integrated circuit operating in the low microwave range and the first matched wideband cryogenic integrated circuit LNA that covers frequencies as low as 0.1 GHz
A 0.5-20GHz quadrature downconverter
A quadrature downconverter with 4GHz IF bandwidth and working over the 0.5–20GHz RF frequency range has been designed, fabricated, and tested. The downconverter uses a frequency doubling and dividing scheme to generate quadrature local oscillator signals from 0.5–17GHz and a pair of Gilbert-cell mixers to perform downconversion. When the IF outputs are combined with a commercial quadrature hybrid, the mixer achieves an image rejection ratio greater than 35dB over the entire band with no on-chip calibration or tuning. The active die area is approximately 0.5 x 1 mm^2
Experimental cryogenic modeling and noise of SiGe HBTs
SiGe devices are an exciting contender for extremely low noise, cryogenically cooled amplifiers. This paper begins with a procedure for extracting a simple equivalent circuit model capable of accurately describing SiGe HBT devices. Next, small-signal modeling results obtained for a 3Ă—0.12Ă—18um^2 SiGe HBT at 15, 40, 77, 120, 200, and 300K are presented along with discussion of performance enhancements due to cooling of the device. Finally, the modeled noise performance is presented as a function of temperature and frequency using the concept of minimum cascaded noise temperature, a figure of merit which incorporates both noise temperature and gain
Microwaves in Quantum Computing
Quantum information processing systems rely on a broad range of microwave
technologies and have spurred development of microwave devices and methods in
new operating regimes. Here we review the use of microwave signals and systems
in quantum computing, with specific reference to three leading quantum
computing platforms: trapped atomic ion qubits, spin qubits in semiconductors,
and superconducting qubits. We highlight some key results and progress in
quantum computing achieved through the use of microwave systems, and discuss
how quantum computing applications have pushed the frontiers of microwave
technology in some areas. We also describe open microwave engineering
challenges for the construction of large-scale, fault-tolerant quantum
computers.Comment: Invited review article, to appear in IEEE Journal of Microwaves. 29
pages, 13 figures, to H
SiGe HBT X-Band LNAs for Ultra-Low-Noise Cryogenic Receivers
We report results on the cryogenic operation of two
different monolithic X-band silicon-germanium (SiGe) heterojunction bipolar transistor low noise amplifiers (LNAs) implemented in a commercially-available 130 nm SiGe BiCMOS platform. These SiGe LNAs exhibit a dramatic reduction in noise temperature with cooling, yielding Teff of less than 21 K (0.3 dB noise figure) across X-band at a 15 K operating temperature. To the authors’ knowledge, these SiGe LNAs exhibit the lowest broadband noise of any
Si-based LNA reported to date
SuperCam, a 64-pixel heterodyne imaging array for the 870 micron atmospheric window
We report on the development of SuperCam, a 64 pixel, superheterodyne camera
designed for operation in the astrophysically important 870 micron atmospheric
window. SuperCam will be used to answer fundamental questions about the physics
and chemistry of molecular clouds in the Galaxy and their direct relation to
star and planet formation. The advent of such a system will provide an order of
magnitude increase in mapping speed over what is now available and
revolutionize how observational astronomy is performed in this important
wavelength regime. Unlike the situation with bolometric detectors, heterodyne
receiver systems are coherent, retaining information about both the amplitude
and phase of the incident photon stream. From this information a high
resolution spectrum of the incident light can be obtained without multiplexing.
SuperCam will be constructed by stacking eight, 1x8 rows of fixed tuned, SIS
mixers. The IF output of each mixer will be connected to a low-noise, broadband
MMIC amplifier integrated into the mixer block. The instantaneous IF bandwidth
of each pixel will be ~2 GHz, with a center frequency of 5 GHz. A spectrum of
the central 500 MHz of each IF band will be provided by the array spectrometer.
Local oscillator power is provided by a frequency multiplier whose output is
divided between the pixels by using a matrix of waveguide power dividers. The
mixer array will be cooled to 4K by a closed-cycle refrigeration system.
SuperCam will reside at the Cassegrain focus of the 10m Heinrich Hertz
telescope (HHT). A prototype single row of the array will be tested on the HHT
in 2006, with the first engineering run of the full array in late 2007. The
array is designed and constructed so that it may be readily scaled to higher
frequencies.Comment: 12 pages, 14 figures, to be published in the Proceedings of SPIE Vol.
6275, "Astronomical Telescopes and Instrumentation, Millimeter and
Submillimeter Detectors and Instrumentation for Astronomy III
- …