A Low-Noise Pre-Amplifier for a He₃ Cooled Infra-Red Bolometer

Abstract

Detection of infra-red radiations at wavelengths of the order of several hundred microns requires use of bolometers cooled at suitable low temperature in a cryostat. Cooling reduces thermal noise generated in the detector and increases its temperature co-efficient of resistance to a high value. Pre-amplifiers used to amplify detected signals should therefore have high input impedance and low noise. A pre-amplifier for doped germanium detector operating at 0.3°K has been described in this article. It has 1GΩ input resistance and 1.75 nV/√ Hz noise at 25 Hz.

Indexing Terms:

• Low-Noise Amplifier
• Bolometer
• FET