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Cryogenic ultra-low-noise SiGe transistor amplifier
B I Ivanov1, M Trgala, M Grajcar
1Institute of Photonic Technology, Jena, Germany.
The Review of Scientific Instruments
|November 4, 2011
Summary
This study presents an ultra-low-noise amplifier designed for cryogenic temperatures. The silicon-germanium heterojunction bipolar transistor amplifier achieves a noise temperature of approximately 1.4 K, making it ideal for sensitive electronic applications.
Area of Science:
- Cryogenic Electronics
- Semiconductor Device Physics
- Low-Noise Amplification
Background:
- Superconducting Quantum Interference Devices (SQUIDs) require highly sensitive amplifiers for operation at cryogenic temperatures.
- Minimizing noise in amplifier design is critical for detecting weak signals in sensitive scientific instruments.
Purpose of the Study:
- To design and characterize an ultra-low-noise, single-stage amplifier suitable for cryogenic environments.
- To evaluate the performance of a silicon-germanium (SiGe) heterojunction bipolar transistor (HBT) amplifier at low temperatures and high frequencies.
Main Methods:
- Design of a one-stage SiGe HBT amplifier optimized for cryogenic operation.
- Measurement of amplifier noise temperature (T(N)) and voltage gain at 4.2 K.
- Characterization of input voltage noise spectral density and power consumption across a frequency range of 10 kHz-100 MHz.
Main Results:
- Achieved a noise temperature T(N) of approximately 1.4 K at 4.2 K for source resistances around 50 Ω.
- Measured a voltage gain of 25 dB with a low power consumption of 720 μW.
- Obtained an input voltage noise spectral density of approximately 35 pV/√Hz.
Conclusions:
- The developed SiGe HBT amplifier exhibits excellent low-noise performance at cryogenic temperatures.
- Its low noise and power consumption make it highly suitable for readout applications, particularly for DC SQUID magnetometers.
- This amplifier represents a significant advancement for sensitive measurement systems operating in extreme thermal conditions.
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