1.
Rev Sci Instrum
; 82(10): 104705, 2011 Oct.
Article
in English
| MEDLINE
| ID: mdl-22047315
ABSTRACT
An ultra-low-noise one-stage SiGe heterojunction bipolar transistor amplifier was designed for cryogenic temperatures and a frequency range of 10 kHz-100 MHz. A noise temperature T(N) ≈ 1.4 K was measured at an ambient temperature of 4.2 K at frequencies between 100 kHz and 100 MHz for a source resistance of ~50 Ω. The voltage gain of the amplifier was 25 dB at a power consumption of 720 µW. The input voltage noise spectral density of the amplifier is about 35 pV/âHz. The low noise resistance and power consumption makes the amplifier suitable for readout of resistively shunted DC SQUID magnetometers and amplifiers.