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
Consider Chebyshev Type I versus Chebyshev Type II (also called inverse Chebyshev) Ölters. Which one should be used based on the following criteria? (If there is no difference betw

Determine self inductance of coil: A flux of 0.5 m Wb is generated by coil A of 600 turns wound on a ring with a current of 2 A in it. Determine (a) self inductance of coil A,

CPU Based Exchange:   In centralized control, all control equipment is replaced by a single processor which should be quite powerful. It should be capable of processing 10 to 100 c

(a) Find the Fourier series for the square wave shown in Figure(a). (b) Let a voltage source having the waveform of part (a) with a peak value of 100 V and a frequency of 10 Hz

Quite often an amplifier is used as a component of an amplifier circuit. Consider the amplifier circuit shown in Figure, which contains an amplifier block as an internal component.

Define addressing modes of 8085. a) Immediate addressing b) Register addressing c) Direct addressing d)  Indirect addressing e)  Implicit addressing

A series RLC circuit consisting of resistor of 200 ohms, an inductor of 0.214H and a capacitor of unknown value. When this circuit is energized by 240 i) value of capacitor ii) vol

Q. Use of N-channel JFET? Generally, N-channel JFETs are more commonly used than P-channel. With no voltage applied between gate and source, the channel is a wide-open path for

Q. Show Frequency response using pspice and probe? PSpice is capable of performing transient circuit analysis, for which the request is given by the following statement: • T

Q. Advantage of digital technology? The primary advantage of digital technology is the low cost, simplicity, and versatility of the digital building blocks. Because digital sig