What causes saturation in transistor?
In saturation mode both of the “diodes” in the transistor are forward biased. That means VBE must be greater than 0, and so must VBC. This value means that VC must be slightly greater than VE (but both still less than VB) to get the transistor in saturation mode.
When is a junction transistor operated under saturated conditions?
When a transistor is operated in a saturation region, the emitter and the collector terminals are at higher potential. When the anode terminal of a junction diode is at higher potential than that of the cathode, the junction diode is said to be forward biased.
What Causes Early effect in bipolar transistor?
The early effect is the variation in the width of the base in a bipolar transistor due to a variation in the applied base-to-collector voltage. For example a greater reverse bias across the collector- base junction increases the collector-base depletion width. If VCE increases VCB increases too.
What is cut-off and saturation?
In cutoff, the transistor appears as an open circuit between the collector and emitter terminals. In the circuit above, this implies Vout is equal to 10 volts. The second region is called “saturation”. This is where the base current has increased well beyond the point that the emitter-base junction is forward biased.
Why an ordinary transistor is called bipolar?
device is often called the bipolar junction transistor because its operation requires that the negatively charged electrons and their positively charged counterparts (the holes corresponding to an absence of electrons in the crystal lattice) coexist briefly in the presence of one another.
What are the operating regions of a bipolar junction transistor?
Operation of Bipolar Junction Transistor There are three operating regions of a bipolar junction transistor: Active region: The region in which the transistors operate as an amplifier. Saturation region: The region in which the transistor is fully on and operates as a switch such that collector current is equal to the saturation current.
How is the forward active mode of a bipolar transistor obtained?
The forward active mode is obtained by forward-biasing the base-emitter junction. In addition we eliminate the base-collector junction current by setting VBC = 0. The minority-carrier distribution in the quasi-neutral regions of the bipolar transistor, as shown in Figure 5.3.1, is used to analyze this situation in more detail.
How to calculate the carrier lifetime of a bipolar junction transistor?
The quasi-neutral region width in the emitter is 1 mm and 0.2 mm in the base. Use m n = 1000 cm 2/V-s and mp = 300 cm 2/V-s . The minority carrier lifetime in the base is 10 ns. Calculate the emitter efficiency, the base transport factor, and the current gain of the transistor biased in the forward active mode.
What is the minority carrier distribution in a bipolar transistor?
The minority-carrier distribution in the quasi-neutral regions of the bipolar transistor, as shown in Figure 5.3.1, is used to analyze this situation in more detail. Figure 5.3.1. : Minority-carrier distribution in the quasi-neutral regions of a bipolar transistor (a) Forward active bias mode.