Characteristics, structure, and performance of a diffused-base germanium oscillator transistor

The diffused-base transistor structure affords a degree of design flexibility not found in previous structures. This is true because it has a larger number of independently adjustable design parameters than the previous structures. Its flexibility has been exploited in an oscillator transistor for 200-mc service. Design analysis shows that low ohmic base resistance, low collector body resistance, and operation at about 0.3 of the collector breakdown voltage are desirable in the present application. The methods of Lee have been used in making this germanium diffused-base unit. Alloyed emitter and base electrodes are parallel stripes approximately 0.5-mil apart, each measuring 1 × 6 mils. The collector is about 4.5 × 8 mils. Typical parameters at Vc= -10 volts and 1E= 10 ma are: fα= 600 mc, = 35 ohms, and Cc= 1.0 mmf. Median 200-mc oscillator efficiency of 50 per cent is obtained at the design bias point of -20 volts, 10 ma; this exceeds the performance objective. The unit withstands 20,000- accelerations in any direction, an additional demand imposed by the specific application for which it was developed.