Summary of bipolar transistor problem:
1. In practical work, Ib*β=V/R is commonly used as the critical saturation condition. According to Ib*β=V/R calculated Ib value, just make the transistor into the initial saturation state, in fact should be taken several times more than the value, in order to achieve true saturation; The larger the multiple, the deeper the saturation.
2. The larger the collector resistance, the easier it is to saturate;
3. The phenomenon of saturation zone is: both PN nodes are positive bias, IC is not controlled by IB