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The CORRECT answer is (a) True

To explain: The SIMPLIFIED common collector (CC) amplifier configuration does not have a collector resistance RC. The collector terminal of the bipolar junction transistor is common to both the input and OUTPUT circuit terminals.

The correct answer is (b) β × (Re + re‘)

Easy explanation: The base impedance of a SIMPLIFIED COMMON collector (CC) AMPLIFIER can be expressed in terms CIRCUIT resistor values. The base impedance is β × (Re + re‘) . Where β is the transistor amplifiers current gain, Re is the equivalent emitter resistance and re‘ is the alternating current resistance of the emitter-base diode.

The correct option is (a) HIGH gain and high bandwidth

Easy explanation: A circuit having a single transistor configuration does not provide SUITABLE bandwidth or gain. To overcome this DIFFICULTY, we COMBINE several amplification stages. The cascading transistor configuration theory is used for high gain as well as high bandwidth.

Correct option is (d) 2

Best EXPLANATION: The total gain of a cascading transistor CONFIGURATION is the ration of the output of SECOND stage amplifier to the input of first stage amplifier. Where, Voutput = 100V and Vinput = 50V.

AV = Voutput / Vinput = 100V / 50V = 2.

Right choice is (a) 1

To ELABORATE: The value of β in a high input resistance transistor amplifier circuit amplifier configuration can be calculated using β = Vf / VO. Given, Vf = 7V and VO = 6.89V:

β = Vf / VO = 7 / 6.89 = 1.01 ≈ 1.

Correct answer is (C) Good high FREQUENCY operation

The explanation is: The cascading transistor CONFIGURATION circuit can be constructed with two configurations of a transistor that is CE (common-emitter) and CB (common base). The CB (common base) configuration DELIVERS a good high-frequency operation.

The correct OPTION is (a) Increase voltage gain

Explanation: A CIRCUIT having a single TRANSISTOR configuration does not provide SUITABLE bandwidth or gain. The purpose of a cascading transistor configuration is to provide an increase in the voltage gain. The total gain of a cascading transistor configuration is the product of the voltage GAINS of the discrete stages.

Correct answer is (c) VO = Ad × Vd + AC × VC

To elaborate: The differential GAIN of a difference amplifier is defined as the gain obtained at the output SIGNAL with respect to the difference in the input signals applied. To calculate the output voltage of a difference amplifier we USE Ad × Vd + AC × VC. Where, Ad is the differential gain and AC and VC represent the common MODE gain.

Right choice is (d) 2

The explanation is: The total gain of a difference AMPLIFIER is the RATIO of the output of second stage amplifier to the input of FIRST stage amplifier. Where, Voutput = 100V and VINPUT = 50V.

AV = Voutput / Vinput = 100V / 50V = 2

Correct answer is (a) 1

Best explanation: If all the RESISTOR VALUES are of the EQUAL value, then the circuit will have a voltage gain equal to exactly ONE or unity. Hence it is also called as a Unity Gain Differential Amplifier. The output voltage expression would be the difference between the TWO voltages.

Correct ANSWER is (a) 1

Easiest explanation: The voltage gain of a high input resistance transistor amplifier circuit amplifier configuration is roughly equal to unity. AV is approximately equal to 1. This is DUE to the relatively high input impedance and low OUTPUT impedance.

The correct CHOICE is (b) Low INPUT resistance

The explanation: The problem with a single operational difference amplifier is its low input resistance. This low input resistance results in a loss of a major component of the signal. Operational Amplifier is INTERNALLY a Differential Amplifier with FEATURES like High Input Impedance, Low OUTPUT Impedance.

Correct answer is (b) Output of first STAGE SENT to coupling device

For EXPLANATION: In multi-stage amplifiers, the output of first stage is coupled to the input of SECOND stage using a coupling device. The coupling devices is typically a capacitor or a transformer. Cascading is known as the process of combining two AMPLIFIER stages using a coupling device.

The correct OPTION is (a) True

Explanation: One of the main functions of the coupling DEVICE in a DIFFERENCE amplifier is to block the direct CURRENT from passing through to the input of next STAGE from the output of the first stage. Another function of the coupling device is to transfer the current from the output of first stage to the input of the second stage.

The CORRECT option is (c) 60dB

Explanation: The total gain of a difference AMPLIFIER is the sum of the multiple stages when the gain is CALCULATED is DECIBELS. Given, AV1 = 10dB, AV2 = 20dB and AV3 = 30dB

AV = AV1 + AV2 + AV3 = 10dB + 20dB + 30dB = 60dB

Correct answer is (a) Increase VOLTAGE gain

The explanation: A circuit having a single transistor configuration does not provide suitable bandwidth or gain. The purpose of a difference AMPLIFIER is to provide an increase in the voltage gain. The total gain of a difference amplifier is the PRODUCT of the voltage GAINS of the discrete STAGES.

Correct choice is (c) 60dB

Explanation: The TOTAL gain of a cascading transistor configuration is the sum of the MULTIPLE stages when the gain is calculated is DECIBELS. Given, AV1 = 10DB, AV2 = 20dB and AV3 = 30dB

AV = AV1 + AV2 + AV3 = 10dB + 20dB + 30dB = 60dB.

The correct CHOICE is (C) Feedback amplifier

For explanation I would say: The emitter follower amplifier is one of the most NOTICEABLE feedback AMPLIFIERS. It provides a negative current feedback to the CIRCUIT. These type of amplifiers are usually used in the end stage or the last stage of a series of amplifiers.

The CORRECT option is (C) hfe / 1 + hfe

Best explanation: The current gain of a simplified common BASE (CB) amplifier can be expressed in terms of approximate HYBRID parameters. The current gain hfe is the forward transfer characteristics. The current gain of a common base amplifier is expressed as hfe / 1 + hfe.

Correct option is (b) 4

The BEST explanation: There are FOUR TYPES of coupling mechanisms USED. They are Resistance – capacitance coupling, THERMAL coupling, impedance coupling and transformer coupling. Resistance – capacitance coupling is the most vastly used mechanism.

Correct option is (a) 0.68

To explain I would say: The voltage gain AV of a simplified COMMON COLLECTOR amplifier configuration can be CALCULATED using AV = RE / (RE + re‘) . GIVEN, RE = 25kΩ and re‘ = 12kΩ:

AV = RE / (RE + re‘) = 25 / 25 + 12 = 25 / 37 = 0.675 ≈ 0.68

The correct choice is (c) IC = hfe × IB

The best I can explain: The collector current of a common emitter (CE) amplifier can be expressed in terms of hybrid PARAMETERS in the simplified CE hybrid MODEL. It is expressed as the product of hfe × IB. This is the same for APPROXIMATE hybrid models as WELL.

Right option is (a) True

The best I can explain: The middle stage of an n-stage cascading amplifier provides most gain. It provides the maximum VOLTAGE gain along with fluctuating the DC level of the SIGNAL. It ALSO converts the signal from one mode to ANOTHER while processing.

The correct answer is (b) ac current GAIN

The BEST I can explain: The ac current gain is GIVEN by β=∆IC/∆IB. When the signal is applied, the ratio of CHANGE of collector current to the ratio of change of base current is called ac current gain.

The CORRECT choice is (c) Low-range frequencies

For explanation: Multistage cascading AMPLIFIERS or n-stage cascading amplifiers have a low CUT off frequency. The gain of the system is compromised at lower frequencies. To calculate the cut off frequency fc = f1 / √(2^1/n – 1), where f1 is initial frequency.

The correct ANSWER is (d) 2.5

The BEST I can explain: The total GAIN of a cascading transistor amplifier is the ration of the output of second stage amplifier to the input of FIRST stage amplifier. Where, Voutput = 25V and Vinput = 10V.

AV = Voutput / Vinput = 25V / 10V = 2.5

The correct answer is (a) 1

Easiest EXPLANATION: The value of β in an emitter follower AMPLIFIER CONFIGURATION can be calculated using β = VF / VO. Given, Vf = 12V and VO = 12V:

β = Vf / VO = 12 / 12 = 1

The correct answer is (d) High

Easy explanation: The CONSTRUCTION of an EMITTER follower CIRCUIT are approximately similar to a normal amplifier. ONE of the most important differentiating feature of an emitter follower circuit is its high power gain.

The correct option is (a) 98.41

Easiest explanation: The VALUE of β in a SIMPLIFIED common base amplifier CONFIGURATION can be calculated USING β = IC / IB. Given, IC = 124mA and IB = 1.26mA:

β = IC / IB = 124 / 1.26 = 98.41

The CORRECT OPTION is (a) hfe × RL / hie

Easiest explanation: The voltage gain of a simplified common base (CB) amplifier can be expressed in terms of approximate hybrid PARAMETERS. The voltage gain is equal to hfe × RL / hie where, RL is load resistance, hie is input resistance of CE amplifier and -hfe is the current gain of CE amplifier.

Right answer is (d) High

To explain I would say: The construction of an emitter follower circuit are APPROXIMATELY similar to a NORMAL amplifier. One of the most IMPORTANT DIFFERENTIATING feature of an emitter follower circuit is its high input impedance.

Correct option is (c) Good high FREQUENCY operation

To explain I would say: The CASCADING transistor amplifier circuit can be constructed with TWO CONFIGURATIONS of a transistor that is CE (common-emitter) and CB (common base). The CB (common base) configuration delivers a good high-frequency operation.

The correct option is (B) Forward biased

The EXPLANATION is: The common base design amplifier works to such an EXTENT that the input signal is applied to the emitter terminal and the yield is taken from the collector terminal. The emitter current is likewise the input current, and the collector current is ADDITIONALLY the yield current. The base-emitter intersection is forward-biased.

Right OPTION is (b) Multistage amplifiers

For explanation I would say: A single STAGE of amplifier provides an insufficient current GAIN or voltage gain. Several amplifier stages CONNECTED in cascade are used instead. Hence it is known as an n-stage CASCADING amplifier of multistage amplifier.

Right option is (d) AVK = AIK × RLK / RiK

Best explanation: The gain for any intermediate stage in an n-stage cascading AMPLIFIER can be calculated using AVK = AIK × RLK / RiK. Where, AIK, RLK and RiK is the estimated with respect to the values of the previous STAGES. AIK represents the voltage gain while RLK and RiK REPRESENT the EFFECTIVE LOAD impedance.

The CORRECT choice is (d) High

The best explanation: The construction of a high input RESISTANCE transistor amplifier circuit is APPROXIMATELY SIMILAR to a normal amplifier. One of the most important differentiating FEATURE of a high input resistance transistor amplifier circuit is its high power gain.

The correct answer is (d) PASS ac & blocks dc

For explanation: In analog circuits, a COUPLING CAPACITOR is used to connect two circuits such that only the AC SIGNAL from the first circuit can pass through to the next while DC is blocked. This technique helps to isolate the DC bias settings of the two coupled circuits.

Correct choice is (a) ∞

For explanation: The output RESISTANCE in a SIMPLIFIED common emitter hybrid model is calculated as the ratio of collector voltage over collector CURRENT while VS is EQUAL to ZERO and RL is omitted. Due to this configuration IC is equal to zero and hence output resistance is infinite.

The correct choice is (c) 1 + HFE

Easiest explanation: The current gain of a simplified COMMON collector (CC) amplifier can be EXPRESSED in terms of approximate hybrid parameters. The current gain hfe is the forward transfer characteristics. The current gain of a common collector amplifier is expressed as 1 + hfe.