1/f models of bipolar junction transistor and their application to PM and AM noise calculation

The aim of this paper is to build a nonlinear circuit model of bipolar junction transistor BJT with the main sources of 1/f fluctuations. A short review of existing circuit models and physical models is presented and their shortcomings are discussed. Than a new circuit model is built basing on the physical model that takes into consideration both 1/f fluctuations in number of electrons on centers in the depletion layer of emitter p-n junction and fluctuations of recombination rate in the base and emitter neutral regions. In the model we have introduced and found not only 1/f noise currents but 1/f parameters fluctuations of BJT nonlinear model (recombination conductivity, emitter-base capacitance). It was shown that in some particular cases this model can be reduced to Plumb-Chenette model and to the model presented and used in our previous papers. The conditions of using of the simplified models are formulated. An example of the model application is presented. It is connected with investigation of 1/f PM noise compensation effect in BJT amplifier. Results of experimental testing of this effect are given. It is shown that minimal level of 1/f PM noise can be explained by emitter-base capacitance fluctuations. Opportunities of other applications of the model are discussed.