How a transistor in common-base configuration amplify signal, Electrical Engineering

Assignment Help:

Q. With a circuit diagram explain how a transistor in common-base configuration amplify signals.

 The common-base terminology is derived from the fact that the base is common to the input and output sides of the configuration. Also the base is the terminal closest to ,or at, ground potential. The input characteristics for a transistor in common base configuration can be obtained by plotting a graph with VBE as x-axis and IE as the y-coordinate at various levels of output voltage VCB. Also the output  characteristics can be observed by plotting VCB along x-axis and IC along y-axis for various levels of IE.

The output or collector set of characteristics has three basic regions of interests : the active, cut-off and saturation regions. The active region is the  region normally employed for linear (undistorted) amplifiers. In the active region the base-emitter junction is forward biased, while the collector-base junction is reverse-biased. 

The signal to be amplified Vs is applied to the input leads, ie. between the emitter and the base. The electrons leaving the base take two paths. A small percentage combines with the holes in the base region and constitute the base current, while the majority of these diffuse towards the collector junction. The collector junction is reverse biased and these electrons can easily cross the junction and form the collector current. This collector current is allowed to pass through a high resistor connected in series with the collector. The voltage  developed across the load resistor is the amplified output voltage.

The amount of collector current depend upon the recombination at the base, the smaller the recombination the larger the collector current. A small base current controls large collector current. If the base-emitter voltage is increased slightly, more electrons are injected into the base region, which will be more than the base can use (recombination). This results in a larger collector current. In short, a smallchange in the base voltage cause very large change in the collector current. This is current amplification. The large collector current passing through the load resistor produces high voltage across which will be several times greater than the small input voltage applied to the input.


Related Discussions:- How a transistor in common-base configuration amplify signal

What is polymerised resultant of phenol and formaldehyde, Phenol and Formal...

Phenol and Formaldehyde are polymerised to a resultant product known as (A) PVC.                                  (B) bakelite. (C)  Polyester.                        (D)

Sketch the circuit with all the relevant labelling, Question: (a) Consi...

Question: (a) Consider the subsequent LC impedance function: (i) If the function is to be realised using the Foster I Form, evaluate the values of the different compon

Cmos integrated circuit design, design using softwares (LEdit7, LTspice) t...

design using softwares (LEdit7, LTspice) the project has many aspects and I would like you to check them on the website with my personal password. in the project specifications (d

How many machine cycles does 8085 have, How many machine cycles does 8085 h...

How many machine cycles does 8085 have, mention them The 8085 have seven machine cycles. They are Opcode fetch Memory read Memory write I/O read I/O

Calculate the e.m.f. generated in armature of a d.c. machine, The armature ...

The armature of a d.c. machine has a resistance of 0.3 and is connected to a 200V supply. Calculate the e.m.f. generated when it is running (a) as a generator giving 80A (b) as a

Obtain the value of rs, Consider and obtain the values for R S , R 2 , R 1 ...

Consider and obtain the values for R S , R 2 , R 1 , and R D . Apply the rule-of-thumb dc design procedure outlined in this section for a JFET with V P = 3V, I DSS = 20 mA, and a

A circuit having of a resistor connected in series, A circuit having of a r...

A circuit having of a resistor connected in series with a 0.5µF capacitor and has a time constant of 12 ms. Verify: (a)  The value of the resistor (b)  The capacitor voltage

Notations that are used in transistor circuits -h parameters, Notations tha...

Notations that are used in transistor circuits:-             h ie = h 11e = Short circuit input impedance             h 0e = h 22e = Open circuit output admittance

What do you mean by continuous signals, Q. What do you mean by Continuous s...

Q. What do you mean by Continuous signals? Continuous signals are described by time functionswhich are defined for all values of t (a continuous variable). Commercial broadcast

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd