Shunted Josephson tunnel junctions: High-frequency, self-pumped low noise amplifiers

Journal Article · Thu Jul 01 00:00:00 EDT 1982 · J. Appl. Phys.; (United States)

DOI:https://doi.org/10.1063/1.331342· OSTI ID:5259177

Calander, N; Claeson, T; Rudner, S

The high-frequency amplification properties of transformer coupled, resistively shunted Josephson tunnel junctions have been investigated. The importance of the shunt loop inductance is stressed. It allows a high cutoff frequency, of significance for good high-frequency performance. The self-pumped parametric amplifier showed none of the excessive noise rise, which has hitherto plagued the development of externally pumped Josephson junction amplifiers. Around 10 GHz, we estimated a noise temperature less than 30 K for an amplifier pumped by a Josephson oscillation with a frequency well above twice the signal frequency. The corresponding gain of 5 dB may be increased in a better impedance matched circuit. The gain was very stable against variations in the bias conditions. A gain-bandwidth product as high as 0.3 was registered. The experimental results agreed well with the established theory for self-pumped parametric Josephson amplifiers. It should be possible to extend the low noise amplification by this device to mm wave frequencies. A relaxation oscillation occurred at a subharmonic of the Josephson frequency when the shunt loop inductance became large. The amplification in this mode followed closely the predictions of a simple model, where the signal modulated the switching of the sawtooth-like (relatively low frequency) relaxation current. Gains of about 15 dB were measured around 10 GHz, but the amplification was sensitive to bias conditions and noisy in this case where the relaxation frequency fell well below the signal frequency. Much improved properties were registered when the inductance was decreased so that the relaxation frequency approached the Josephson frequency and exceeded twice the signal frequency. The behavior then resembled that of a Josephson mode parametric amplifier, but the high content of harmonics of a relaxation oscillation meant that the amplifier became noisier due to converted noise from the many idler frequencies.

• Research Organization: Physics Department, Chalmers University of Technology, S-412 96 Gothenburg, Sweden
• OSTI ID: 5259177
• Journal Information: J. Appl. Phys.; (United States), Vol. 53:7
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
JOSEPHSON JUNCTIONS
AMPLIFIERS
NOISE
COMPARATIVE EVALUATIONS
COUPLING
EXPERIMENTAL DATA
GAIN
GHZ RANGE 01-100
MATHEMATICAL MODELS
PARAMETRIC AMPLIFIERS
PERFORMANCE
STABILITY
TRANSFORMERS
TUNNEL EFFECT
AMPLIFICATION
DATA
ELECTRICAL EQUIPMENT
ELECTRONIC EQUIPMENT
EQUIPMENT
FREQUENCY RANGE
GHZ RANGE
INFORMATION
JUNCTIONS
NUMERICAL DATA
SUPERCONDUCTING JUNCTIONS
420201* - Engineering- Cryogenic Equipment & Devices