An 8-20-GHz wide-band LNA design and the analysis of its input matching mechanism

A wide-band low-noise amplifier (LNA) design is presented with -10 dB input reflection coefficient and 100-K noise temperature over the 8-20-GHz frequency range at room temperature. This LNA can be cooled down in a liquid helium cryostat to have 10-K noise temperature for the purpose of radio-astronomy application. To achieve its wide-band characteristics, a novel input matching mechanism is proposed, which combines the high-frequency inductive feedback and the low-frequency capacitive feedback. The recognition and comprehensive interpretation of this new input matching mechanism is crucial for future development of ultra-wide-band LNAs.