Mcqs Of Transistor Biasing | Chapter Review Topics | Discussion
Mcqs of Transistor Biasing which are most important for Electrical and Electronic Engineer. Normally These Mcqs of Transistor Biasing come in many technical job tests. these Mcqs of Transistors Biasing are prepared for the job seekers which are taken from Books.
Transistor biasing represents …….. conditions. (i) a.c. (ii) d.c. (iii) both a.c. and d.c. (iv) none of the above
Transistor biasing is done to keep …….. in the circuit. (i) proper direct current (ii) proper alternating current (iii) the base current small (iv) collector current small
Operating point represents ……. . (i) values of IC and VCE when signal is applied (ii) the magnitude of signal (iii) zero signal values of IC and VCE (iv) none of the above
If biasing is not done in an amplifier circuit, it results in …….. (i) decrease in base current (ii) unfaithful amplification (iii) excessive collector bias (iv) none of the above
Transistor biasing is generally provided by a …….. (i) biasing circuit (ii) bias battery (iii) diode (iv) none of the above
For faithful amplification by a transistor circuit, the value of VBE should ………. for a silicon transistor. (i) be zero (ii) be 0.01 V (iii) not fall below 0.7 V (iv) be between 0 V and 0.1 V
For proper operation of the transistor, its collector should have ……… (i) proper forward bias (ii) proper reverse bias (iii) very small size (iv) none of the above
For faithful amplification by a transistor circuit, the value of VCE should …….. for silicon transistor. (i) not fall below 1 V (ii) be zero (iii) be 0.2 V (iv) none of the above
The circuit that provides the best stabilization of operating point is ………. (i) base resistor bias (ii) collector feedback bias (iii) potential divider bias (iv) none of the above
The point of intersection of d.c. and a.c. load lines represent……… (i) operating point (ii) current gain (iii) voltage gain (iv) none of the above
An ideal value of stability factor is …….. (i) 100 (ii) 200 (iii) more than 200 (iv) 1
The zero signal IC is generally …… mA in the initial stages of a transistor amplifier. (i)4 (ii) 1 (iii)3 (iv) more than 10
If the maximum collector current due to signal alone is 3 mA, then zero signal collector current should be atleast equal to ……… (i) 6 mA (ii) 1.5 mA (iii) 3 mA (iv) 1 mA
The disadvantage of base resistor method of transistor biasing is that it …….. (i) is complicated (ii) is sensitive to changes in β (iii) provides high stability (iv) none of the above
The biasing circuit has a stability factor of If due to temperature change, ICBO changes by 1 µA, then IC will change by …….. (i) 100 µA (ii) 25 µA (iii) 20 µA (iv) 50 µA
For good stabilisation in voltage divider bias the current I flowing through R1 and R2 should be equal to or greater than …….. (i) 10 IB (ii) 3 IB (iii) 2 IB (iv) 4 IB
The leakage current in a silicon transistor is about ……… the leakage current in a germanium transistor. (i) one hundredth (ii) one tenth (iii) one thousandth (iv) one millionth
The operating point is also called the …….. (i) cut off point (ii) quiescent point (iii) saturation point (iv) none of the above
For proper amplification by a transistor circuit, the operating point should be located at …….. of the d.c. load line. (i) the end point (ii) middle (iii) the maximum current point (iv) none of the above
The operating point …….. on the a.c. load line. (i) also lies (ii) does not lie (iii) may or may not lie (iv) data insufficient
The disadvantage of voltage divider bias is that it has …….. (i) high stability factor (ii) low base current (iii) many resistors (iv) none of the above
Thermal runaway occurs when …….. (i) collector is reverse biased (ii) transistor is not biased (iii) emitter is forward biased (iv) junction capacitance is high
The purpose of resistance in the emitter circuit of a transistor amplifier is to ……….. (i) limit the maximum emitter current (ii) provide base-emitter bias (iii) limit the change in emitter current (iv) none of the above
In a transistor amplifier circuit, VCE = VCB +……….. (i) VBE (ii) 2 VBE (iii) 1.5 VBE (iv) none of the above
The base resistor method is generally used in ……… (i) amplifier circuits (ii) switching circuits (iii) rectifier circuits (iv) none of the above
For germanium transistor amplifier, VCE should ……… for faithful amplification. (i) be zero (ii) be 0.2 V (iii) not fall below 0.7 V (iv) none of the above
In a base resistor method, if the value of β changes by 50, then collector current will change by a factor of …….. (i) 25 (ii) 50 (iii) 100 (iv) 200
The stability factor of a collector feedback bias circuit is …….. that of base resistor bias. (i) the same as (ii) more than (iii) less than (iv) none of the above
In the design of a biasing circuit, the value of collector load RC is determined by …….. (i) VCE consideration (ii) VBE consideration (iii) IB consideration (iv) none of the above
If the value of collector current IC increases, then value of VCE …….. (i) remains the same (ii) decreases (iii) increases (iv) none of the above
If the temperature increases, the value of VBE ……. (i) remains the same (ii) is increased (iii) is decreased (iv) none of the above
The stabilisation of operating point in potential divider method is provided by …….. (i) RE consideration (ii) RC consideration (iii) VCC consideration (iv) none of the above
The value of VBE ………… (i) depends upon IC to moderate extent (ii) is almost independent of IC (iii) is strongly dependent on IC (iv) none of the above
When the temperature changes, the operating point is shifted due to …….. (i) change in ICBO (ii) change in VCC (iii) change in the values of circuit resistances (iv) none of the above
The value of stability factor for a base-resistor bias is …….. (i) RB (β + 1) (ii) (β + 1) RC (iii) (β + 1) (iv) 1 − β
In a practical biasing circuit, the value of RE is about ……. (i) 10 kΩ (ii) 1 (iii) 100 kΩ (iv) 800 Ω
A silicon transistor is biased with base resistor method. If β = 100, VBE = 0.7 V, zero signal collector current IC = 1 mA and VCC = 6 V, what is the value of base resistor RB ? (i) 105 kΩ (ii) 530 kΩ (iii) 315 kΩ (iv) none of the above
In voltage divider bias, VCC = 25 V ; R1=10 kΩ; R2 = 2.2 kΩ ; RC= 3.6 kΩ and RE=1 kΩ. What is the emitter voltage ? (i) 6.7 V (ii) 5.3 V (iii) 4.9 V (iv) 3.8 V
In the above question, what is the collector voltage ? (i) 12.3 V (ii) 14.8 V (iii) 7.6 V (iv) 9.7 V
In voltage divider bias, operating point is 3 V, 2 mA. If VCC = 9 V, RC = 2.2 kΩ, what is the value of RE ? (i) 2000 Ω (ii) 1400 Ω (iii) 800 Ω (iv) 1600 Ω
Review TopicsOf Transistor Biasing
What is a faithful amplification? Explain the conditions to be fulfilled to achieve faithful amplification in a transistor amplifier.
What do you understand by transistor biasing? What is its need?
What do you understand by stabilization of the operating point?
Mention the essentials of a biasing circuit.
Describe the various methods used for transistor biasing. State their advantages and disadvantages.
Describe the potential divider method in detail. How the stabilization of the operating point is achieved by this method?
Mention the steps that are taken to design the transistor biasing and stabilization circuits.
Write short notes on the following : (i) Operating point (ii) Stabilisation of operating point
An NPN silicon transistor has VCC = 5V and the collector load RC = 2 kΩ. Find : (i) the maximum collector current that can be allowed during the application of signal for faithful amplification (ii) the minimum zero signal collector current required [ (i) 2mA (ii) 1mA]
Fig. 9.48 shows biasing with base resistor method. Determine the operating point. Assume the transistor to be of silicon and take β = 100. [ IC = 0.93 mA, VCE = 17.3V]
Fig. 9.49 shows biasing bybase resistor method. If it is required to set the operating point at 1mA, 6 V, find the values of RC and RB. Given β =150, VBE = 0.3 V.[ RC= 3 kΩ, RB = 0.3 MΩ]
A transistor amplifier is biased with feedback resistor RB of 100 kΩ. If VCC = 25 V, RC= 1 kΩ and β = 200, find the values of zero signal IC and VCE. [IC = 16.2mA, VCE = 8.8V]
Find the value of IC for potential divider method if VCC = 9V, RE= 1kΩ, R1 = 39 kΩ, R2 = 10kΩ, RC = 2.7 kΩ, VBE = 0.15 V and β = 90. [1.5mA]
In an RC coupled amplifier, the battery voltage is 16V and collector load RC = 4 kΩ. It is required to set the operating point at IC = 1mA, VCE = 10V by potential divider method. If VBE = 0.2 V and I1 = 10 IB, β = 100, find the various circuit values.
In the transistor circuit shown in Fig. 9.50, find the operating point. Assume the transistor to be of silicon. [IC= 10.5mA, VCE = 7.75V]
In a transistor circuit shown in Fig. 9.51, find the operating point. Assume a silicon transistor is used. [IC= 0.365mA, VCE = 8.9V]
Determine whether or not the circuit shown in Fig. 9.52 is midpoint biased. [Yes]
What fault is indicated in Fig. 9.53 ? Give reasons for your answer. [RC is open]
Determine IB, IC and VCE for a base-biased transistor circuit with the following values : β = 90; VCC = 12V; RB = 22 kΩ and RC = 100Ω. [IB= 514 µA ; IC = 46.3 mA ; VCE = 7.37V]
The base bias circuit in Fig. 9.54 is subjected to a temperature variation from 0°C to 70°C. The β decreases by 50% at 0°C and increases by 75% at 70°C from its normal value of 110 at 25°C. What are the changes in IC and VCE over the temperature range of 0°C to 70°C? [IC = 59.6 mA ; VCE = 5.96V]
To what value can RE in Fig. 9.55 be reduced without transistor going into saturation? [639Ω]
When can the effect of β be neglected in the emitter bias circuit? [When RE>> RB/β]
What is the minimum value of β in Fig? 9.56 that makes Rin (base)≥ 10 R2? [69.1]
(i) Determine the base voltage VB in Fig. 9.57. (ii) If RE is doubled, what will be the value of VB? [(i) 1.74V (ii) 1.74V]
(i) Find the Q-point values for Fig. 9.57. (ii) Find the minimum power rating of transistor in Fig. 9.57.[(i) 1.41 mA ; – 8.67V (ii) 12.2mW]
A collector-feedback circuit uses an npn transistor with VCC = 12V, RC= 1.2 kΩ, RB= 47 kΩ. Determine the collector voltage and the collector current if β = 200. [7.87 mA ; 2.56V]
Discussion Questions of Transistor Biasing
Why are transistor amplifiers always operated above knee voltage region ?
What is the utility of d.c. load line ?
Why have transistors inherent variations of parameters ?
Why is βd.c. different from βa.c. ?
Why has potential divider method of biasing become universal ?