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level: BJT

Questions and Answers List

level questions: BJT

Question	Answer
Transistor is a device which is a____. A.Transferring voltage device B.Current operated one C.Power operated one D.Voltage operated one	B. Current operated one
Transistor works as an open switch when emitter junction is.......biased and collector junction is_____biased. A.Forward, forward B.Reverse, reverse C.Reverse, forward D.Forward, reverse	B.Reverse, reverse
The transistor can be operated in A.Active region B.Saturation region C.Cut-off region D.All of the above regions	D. All of the above regions
Transistor is said to be operating in the active region if A.Emitter junction is forward biased and collector junction is reverse biased B.Emitter junction is reverse biased and collector junction is forward biased C.Emitter junction is reverse biased and collector junction is reverse biased	A
The transistor is said to be in the____region when both the junctions are forward biased A.Saturation B.Cut-off C.Active D.Passive	A.Saturation
A transistor is said to be operating in the cut-off region if____ A.Emitter junction is forward biased and collector junction is forward biased B.Emitter junction is reverse biased and collector junction is reverse biased C.Emitter junction is forward biased and collector junction is reverse biased	B.Emitter junction is reverse biased and collector junction is reverse biased
_______is the best electronic device for fast switching A.UJT B.JFET C.BJT D.MOSFET	C.BJT
Full form of BJT______	Bipolar Junction Transistor
In a BJT A.The base region is sandwiched between emitter and collector B.The collector is sandwiched between base and emitter C.The emitter region is sandwiched between base and collector D.None of the above	A.The base region is sandwiched between emitter and collector
BJT is a _____ A. Current controlled device B. Voltage controlled device C. Both A and B D. None of the above	A. Current controlled device
In a p+-n-p transistor, the region which serves as the source of injected holes is called _______ A.collector region (p+) B. Emitter region (p) C. Base region (n) D. Emitter region (p+)	D.Emitter region(p+)
Name the region which is (i) heavily doped (ii) lightly doped in a PNP transistor.	Heavily doped-emitter region Lightly doped-base region
In a PNP transistor, the dominant source of base current __ A. Recombination in the base B. Injection of holes into the emitter region C. Both A and B D. None of them	C. Both A and B
In a BJT as collector to base voltage increases the emitter current A.Remains same B.Increases slightly C.Decreases slightly D.Depends upon doping of the emitter region	A.Remains same
In a PNP transistor, the recombination of injected holes in the base is reduced by___ A. Lp << Wb B. Lp = Wb C. Wb << Lp	C.Wb << Lp
Name any one basic application of transistors.	Amplifiers, switches, oscillators,etc..
In which of the following circuit configurations the base current is controlled independently. A. Common Emitter circuit B. Common base circuit C. Common collector circuit	B. Common base circuit
The expression for the emitter injection efficiency (γ) is given by A.γ = iEp / (iEn + iEp) B.γ = iEn / (iEn + iEp) C. None of them	A.γ = iEp / (iEn + iEp)
ic = B*iEp The proportionality factor 'B' in the above expression is called ____ A. Current amplification factor B. Base transport factor C. Both A and B	B. Base transport factor
The relation between collector and emitter current is given by A. ic/iE = α Β. iE/ic = β C. ic /iE = Bγ	Α or C
The collector current can be controlled by variations in small ____ A. Base current B. Collector current C. Emitter Current D. None of the above	A. Base current
The factor β relating the collector current to the base current is called ___ A. Current amplification factor B. Base-to-collector current amplification factor C. Common base collector gain	B
'τt ' is called as A. Transit time B. Average Hole life time C. None	A. Transit time
Give the relation between α and β.	β=α/1-α
The figure shows the approximate hole distribution in the base . This is component due to injection and collection in the______mode.	Normal mode
iEn = iEs [e^(qVeb/kT ) - 1],∆pc=0 The above equation gives the emitter current in______mode. Where iEs is _________.	Normal mode magnitude of emitter saturation current
The above relations gives the total current in a transistor and these relations are referred to as ________equations.	Ebers-Moll
Which property is illustrated by the equivalent circuit shown in the figure?	Coupled Diode property
The figure shows the approximate hole distribution in the base and This component is due to ______ mode.	Inverted
The transistor is in ____ state, when base current is zero or negative and collector current is negligible. A. On B. Off C. Saturation D. Inverted	B. Off
If the base current is positive and sufficiently large, the device is driven to _____region. A. Normal B. Saturation C. Cutoff D. Inverted	B. Saturation
State of the transistor in saturation region-__ A. Normal B. On C. Inverted D. Off	B.On
Wb stands for _____ A. Base width modulation B. Base width C. Effective width D . None of the above	B. base width
Who discovered early effect? A. William Shockley B. John Bardeen C. Walter Brattain D. None of the above	None of the above (J.M.Early)
Saturation can be reached by increasing _____current A. Emitter current (iE) B. Base current (iB) C. Collector current ( iC)	B. Base current (iB)
Expression for collector current in switching effects of common emitter transistor. A .Ic = Ecc/RL B .Ic = Ece/RL C. Ic = Ebe/RL	A. Ic = Vcc/RL
In the above graph, to( t not) represents____ A. cutoff B. normal active region C. beginning of saturation D. final saturated state	A . Cut off
In the figure- C represents the time taken by the collector current to reach from it's initial value to 10% of its final value and is called _____time	Delay time -while junction capacitance is charging.
B represents --The time required for the collector current to rise from 10 to 90% of its value is called _____. C represents -- The time required for the collector current to fall through a similar fraction to turn off excursion is called _____.	B- Rise time C- Fall time
Which is the expression for built in electric field due to the drift in base region ?	A)
What is the important result due to the graded doping of base region ? A. Electric field exists from collector to emitter B. Built in electric field exists from emitter to collector C. Electric field exists in the base region D. None of them	B. Built in electric field exists from emitter to collector
When the collector voltage is increased , the space charge layer takes up more of the metallurgical width of the base Lb and as a result, the effective base width Wb is decreased. This effect of called as ______.	Base narrowing or base-width modulation or early effect
Due to the early effect, the decrease in Wb causes β to ____. A. Decreases B. Increases C. Remains same D. First increases then decreases	B . Increase
If base region is lightly doped , depletion region at reverse biased collector junction can extend into ______ region. A. n-type region B . p-type region C. p-n region D. n-p region	A.n-type region
What's the difference between zener and avalanche breakdown ?	Zener breakdown occurs because of high electric field Avalanche Breakdown is due to the commission of free electrons with atoms
Avalanche breakdown in a diode occurs when ________ is applied across the diode. A. low reverse voltage B. High forward voltage C. High reverse voltage D. Low forward voltage	C. High reverse voltage
Why is isolation of adjacent BJT's necessary?	To avoid electrical cross-talk between them.
Isolation of adjacent BJT'S is achieved by____. A. LOCOS B. LOCUS C. LPCVD D.RIE	A.LOCOS
How is polysilicon layer deposited ? A . LOCOS B. LOCUS C. LPCVD D. RIE	C.LPCVD
How are the IC's separated into the individual dies? A. CVD B. Sawing C. RIE D. LPCVD	B . Sawing