Matched wideband low-noise amplifiers for radio astronomy
Two packaged low noise amplifiers for the 0.3–4 GHz frequency range are described. The amplifiers can be operated at temperatures of 300–4 K and achieve noise temperatures in the 5 K range (<0.1 dB noise figure) at 15 K physical temperature. One amplifier utilizes commercially available, plastic-packaged SiGe transistors for first and second stages; the second amplifier is identical except it utilizes an experimental chip transistor as the first stage. Both amplifiers use resistive feedback to provide input reflection coefficient S11<−10 dB over a decade bandwidth with gain over 30 dB. The amplifiers can be used as rf amplifiers in very low noise radio astronomy systems or as i.f. amplifiers following superconducting mixers operating in the millimeter and submillimeter frequency range.
Additional Information©2009 American Institute of Physics. Received 18 January 2009; accepted 3 March 2009; published 20 April 2009. We acknowledge the contribution through Pascal Chevalier, STMicroelectronics, of the excellent experimental transistor used in the ST amplifier. # Astronomical and space-research instrumentation # 84.30.Vn Filters (electronic circuits)