Transistor biased in active region11/30/2023 Once in the collector, they become majority carriers again, and travel freely to the metal collector terminal. Because they are minority carriers, they pass over the base-collector junction easily, and enter the collector. If the base is thin, and the average path of an electron before recombining is long enough, the electrons will reach the base-collector junction. They don't recombine with holes in the base immediately. When the base-emitter junction of an (NPN) transistor is forward biased, electrons cross over from the N-region emitter to the P-region base. What happens in a PNP transistor is similar except that the roles of electrons and holes is swapped. The diode is conducting current either way.įor the sake of simplicity, in what follows, when I refer to a "transistor", I will mean an NPN transistor. Whether it is mostly electrons crossing the depletion region or mostly holes crossing the depletion region doesn't really matter in a diode. If the N-region is more heavily doped than the P-region, then more electrons will cross over from the N-region into the P-region, than holes will cross over from the P-region to the N-region. Similarly, when holes cross over from the P-region to the N-region, they do not immediately combine with electrons, but continue travelling for some distance as minority carriers. They are minority carriers because they are electrons in a P-regions. When electrons cross over from the N-region to the P-region, they do not immediately combine with holes, but continue travelling for some distance as "minority carriers". When there is enough voltage between the N-region and P-region, electrons will cross from the N-region to the P-region, and holes will cross from the P-region to the N-region. If the voltage between the N-region and the P-region is insufficient, very few electrons in the N-region cross the depletion layer, and very few holes in the P-region cross the depletion layer. Inside a diode there are three regions, an N-region, a P-region, and at the junction between them, a depletion layer. What I present here is a simplification which I hope is accurate enough. It means that the base voltage must be less than the collector but greater than the emitter.However there is no collector base voltage that we must overcome since as soon as we apply 0.7 volts to the base the transistor already conducts between emitter and collector without offering resistanceįor a full explanation, please consult a text on semiconductor theory. In order to operate in active mode, the transistor’s voltage in base-emitter junction must be greater than zero while in base-collector mode must be negative. In the active region, the emitter-base is forward biased and the collector-base is reverse biased.Unlike the resistors, which have a linear relation between voltage and current, the transistors are nonlinear devices. Note:Biasing to the transistor ensures that it operates in the active region. Emitter size is more than base but less than the collector. Section which collects the majority of charge carriers and supplied by the emitter is called collector. Emitter base injects a large amount of charge carrier to the base. In the p-n-p transistor the operation is in the active region, whereas in the n-p-n transistor the operation is in the active region. Saturation: Emitter diode and collector diode are on.Īctive: In the active region, the emitter diode is on and the collector diode is off.Collector base junction is reverse biased, whereas base emitter junction is forward biased.The transistor is said to operate in the active region. The transistor in this operates in an active region, when the collector junction is reverse biased and emitter junction is forward biased.The transistor will function normally.Ĭut-Off: In the cut-off region, the emitter diode and collector diode are off. Now we are going to discuss the active region and give options in detail step by step in the complete step by step solution.Īctive region lies between saturation and cutoff. In this region the transistor acts well as an amplifier. Hint:In which transistors have many applications is called active region.
0 Comments
Leave a Reply.AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |