The lateral base resistance is a fundamental limitation of high-frequency and high speed performance of BJTs. At low temperatures, deionization of the dopant impurity could increase the base resistance much more than the increase of mobility because of lower phonon scattering at lower temperatures. What is the base resistance at 77K corresponding to the 300K base resistance calculated in (736.6). Take into account each of the following factors individually in a n/p/n transistor and show how much effect each contributes: the deionization of the acceptor dopant impurity in the base layer at low temperatures, the increase of mobility due to less phonon scattering and the decrease of mobility due to more ionized and neutral impurity scattering. Use the result of chapter 3 to calculate the mobility due to ionized and neutral impurity scattering. Since some of these factors improve and others degrade as the temperature is lowered, is there a temperature where rb, is a minimum and what is it if there is in this example?