A low-noise distributed amplifier using cascode-connected BJT terminal circuit

This paper describes a low-noise distributed amplifier that uses cascode-connected bipolar junction transistor (BJT) terminal circuit. This amplifier has a lower NF compared with a resistance-terminated distributed amplifier, yet has an equivalent frequency characteristic, because the cascode-connected BJT terminal circuit improves noise performance at low frequencies and keeps the matching condition up to high frequency. The noise figure of the fabricated amplifier was less than 8.3 dB over a range of 0.1-8 GHz, which was about 1 dB better than that of a conventional distributed amplifier, without deterioration in gain and bandwidth. We obtained a flat gain characteristic of 9.7/spl plusmn/1.0 dB over a range of 3-15 GHz.