Noise performance of transistors

The accuracy with which the Beatie lumped model represents transistor noise performance is experimentally verified. The noise model consists of three statistically independent shot-noise generators connected across the lumped elements representing the generation-recombination and diffusion mechanisms of the transistor. In addition a thermal-noise generator is used to represent the noise contributed by the base spreading resistance. By comparing measurements with calculations based on the model, not only is good over-all agreement obtained, but it becomes evident that certain bias and source conditions allow separate confirmation of the internally postulated noise generators. The statistical properties of transistor noise are studied using a laboratory-constructed amplitude-probability density analyzer. The results show that the first-order amplitude distribution function of transistors is indeed gaussian.