Technology of Micro-Alloy Diffused Transistors

Various designs of the micro-alloy diffused transistor (MADT) have been perfected for different classes of service. A highspeed switching version, operating in low-voltage saturating circuits with a current gain of 10, gives turn-off and turn-on times of 5 m¿sec. Base-gated scale-of-two counters have operated at input rates as high as 140 megapulses per second with these transistors. A highfrequency, low-noise amplifier provides neutralized gain of 20 db at 100 mc with a noise figure of 4 db. A high-frequency, high-power oscillator-amplifier having a thermal impedance of 100°C per watt yields power outputs as great as 1.0 w at 70 mc. This paper discusses the control of design variables, including base width, impurity gradient, and positioning of emitter and collector junctions in the gradient, and describes some of the new circuit and measurement techniques evolved for these units.