A planar germanium microwave amplifying transistor with 3 db noise figure at 1.3 Gc

A program was conducted to develop a small signal amplifying transistor with a 3.0 db noise figure at 1.3 Gc. To reach this objective, it was necessary to achieve the minimum noise figure, which occurs at low emitter currents. This requires a compromise between rb¹and the reduced emitter area, consistent with high current density. The high current density is needed to achieve adequate gain at 1.3 Gc. Low rb¹on the other hand, implies a long stripe geometry. The alloyed emitter used was 0.9-mil long and 0.2-mil wide with a 0.1-mil window in the overlying oxide for the contact. The lowest noise figure was obtained at IE= 1.5 ma. The average noise figure of the state-of-the-art samples measured at this current was 3.1 dB at 1.3 Gc.