Cryogenic low-noise amplifiers for measurements with superconducting detectors

Area of Science:

• Cryogenic electronics
• Semiconductor device physics
• Low-noise amplifier design

Background:

• Differential amplifiers are crucial for sensitive measurements.
• Operating electronic components at cryogenic temperatures presents unique challenges.
• Silicon bipolar junction transistor (BJT) technology offers potential for high-performance cryogenic applications.

Purpose of the Study:

• To design, implement, and characterize Si BJT-based differential amplifiers for cryogenic operation.
• To evaluate the performance of these amplifiers at various low temperatures (300 K, 77 K, 48 K).
• To investigate noise reduction techniques for cryogenic amplifiers.

Main Methods:

• Design and fabrication of differential amplifiers using Si BJT technology.
• Experimental characterization of amplifier gain, noise spectral density, and frequency response at cryogenic temperatures.
• Implementation and testing of a parallel differential circuit configuration for noise reduction.

Main Results:

• Achieved high voltage gain exceeding 60 dB at 300 K, 77 K, and 48 K.
• Minimum voltage noise spectral density of 0.33 nV/Hz^0.5 with 20 Hz flicker noise achieved at 77 K.
• Demonstrated a maximum voltage gain of 70 dB at 77 K across DC to 17 kHz.
• Showed that a parallel differential circuit design reduced voltage noise from 0.55 to 0.33 nV/Hz^0.5 at 77 K.

Conclusions:

• Si BJT technology is suitable for high-gain, low-noise differential amplifiers at cryogenic temperatures.
• The parallel differential circuit design effectively minimizes voltage noise at 77 K.
• These cryogenic amplifiers are promising for applications requiring high sensitivity in low-temperature environments.