Therefore a current ICBO flows from the collector terminal to the base terminal due to minority carriers. When these minority carriers come close to the depletion region an electric field is generated between electrons(minority carriers) present in the p-region and positive charge present in the depletion region due to this the electrons from the p-region(Base Terminal) are transferred towards n-region(Collector Terminal). It is observed that when the surrounding temperature increases electrons(minority carriers) present in the p-type region moves towards the n-type region, similarly holes(minority carriers) present in the n-type region moves towards p-type region. electrons are more in number and holes are less in number that is holes are minority carriers in N-region. Similarly In N-region negative charges i.e. Since 100$ is your maximum limit therefore you can consider it as a load line.Ģ) Need of biasing a transistor Individual dependence of Ic and Thermal Individual Variations:-When you replace a transistor it's some parameters like Vbe and β changes as a result q-point also changes due to which a proper amplified version of the input signal is not obtained at the Temperature Dependence Of Ic and The rmal Runaway:-Īs we had discussed earlier the P-region has more positive charges & it also contains a very less number of electrons which we call as minority carriers. You can spend 30$ or 80$ or 99$ but surely not less than 0$ and not more than 100$. Let's take a small example so that the whole picture will be more clear consider that you have 100$ with you, and you and your friend are going to a party so how much money you spend in that party is like your q-point. So basically you can operate the transistor according to your desire. Since transistors are mainly used for amplification purposes so we are superimposing the weak Ac input signal which may be of a few mv with dc voltage and at the load resistor we are getting the amplified version of the input signal therefore this line is known as Ac load-line.When the Ac input signal is not applied and we are only dealing with dc analysis then the load line is known as dc load line.Īny point present on the load-line is known as a q-point. There are 2 types of load-line Ac and Dc load-line. As you can see above,a load line is a line drawn between 2 maximum points that is between Vce(max)=Vcc and Ic(max)=Vcc/Rc.
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