Structure and use of pnp transistor, Electrical Engineering

Structure and use of PNP transistor:

The figure opposite is a schematic presentation of a PNP transistor related to two voltage sources. To construct the transistor conduct appreciable current (on the order of 1 mA) from E to C, VEB have to be above a minimum value occasionally considered to like the cut-in voltage. The cut-in voltage is generally about 600 mV for silicon BJTs at room temperature but can be different depending upon the type of transistor and its biasing. This applied voltage results the upper P-N junction to 'turn-on' permitting a flow of holes from the emitter into the base. In active mode, the electric field lay between the emitter and the collector (caused by VCE) causes the majority of these holes to cross the lower P-N junction into the collector to make the collector current IC. The remainder of the holes again combines with electrons, the majority carriers in the base, forming a current through the base connection to make the base current, IB. As displayed in the diagram, the emitter current, IE, is the total transistor current that is the sum of the other terminal currents (that is., IB=IB+IC).

In the figure, the arrows presenting current point in the direction of conventional current - the flow of holes is in similar direction of the arrows since holes carry positive electric charge. The ratio of the collector current to the base current is termed as the DC current gain, in active mode. This gain is generally 100 or more, but robust circuit designs do not depend upon the exact value. The value of this gain for DC signals is considered to as hFE, and the value of this gain for AC signals is considered to as hfe. Though, when there is no specific frequency range of interest, the symbol β is employed.

It should as well be noted that the emitter current is related to VEB exponentially. At room temperature, increment in VEB by approximately 60 mV increases the emitter current by a factor of 10. Since the base current is approximately proportional to the collector and emitter currents, they vary in similar way.

Posted Date: 1/10/2013 6:52:06 AM | Location : United States







Related Discussions:- Structure and use of pnp transistor, Assignment Help, Ask Question on Structure and use of pnp transistor, Get Answer, Expert's Help, Structure and use of pnp transistor Discussions

Write discussion on Structure and use of pnp transistor
Your posts are moderated
Related Questions
To design a VI that can be used to show how the voltage falls across a resistor in a simple CR circuit when excited by a step function. The title of the VI will be Capacitor Res


This is a synchronous motor that does not require a special start-up auxiliary motor. The  rotor  consists  of  stout  copper  (or aluminium)  conductors  arranged  in  the form of

the plot of amper circuital law by using matlap?

Q. The energy stored in a 2-µH inductor is given by w L (t) = 9e -2t µJ for t ≥ 0. Find the inductor current and voltage at t = 1 s.

Zero-Bias Equilibrium In a p-n junction, with no an external applied voltage, an equilibrium condition is arrived at in which a potential variation is formed across the juncti

Explain the effect of a dielectric on the behaviour of a capacitor. If two parallel plates are separated by a distance 'd' (meters) in vacuum and are kept at a potential diffe

1- phase  Full Bridge Inverter with R- Load 1-phase full  bridge inverter with resistive load R i it has  advantage over 1-? half  bridge  inverter that it does  not require

A forward converter has the following parameters: input source voltage V s = 100 V, N 1 /N 2 = N 1 /N 3 = 1, magnetizing inductance L m = 5 mH, output inductor L o = 200 μH, C

Write explanatory notes on Hard disk drive controller. Hard disk drive controller: It converts instructions from software running upon the computer to the electrical signals