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Correct option is (a) True

The best I can explain: One of the MAIN functions of the coupling device in a CASCADING transistor 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.

Correct option is (d) 7.38V

To explain I would say: The voltage VB of a simplified common collector AMPLIFIER configuration can be calculated using VB = I × R2. GIVEN, VCC = 12V and R1 = 5kΩ and R2 = 8kΩ:

I = VCC / R1 + R2 = 12 / (5 + 8) = 0.92mA

VB = I × R2 = 0.92mA × 8kΩ = 7.38V

Right ANSWER is (c) 10dB

Easiest explanation: A decibel is ten TIMES the value of power in its logarithm in base 10. Therefore a 10dB change is RESULTANT of a change in power by a factor of 10. HOWEVER, when calculating in terms of amplitude the change is DUE to a factor on 20.

Correct answer is (a) High GAIN and high BANDWIDTH

Easy explanation: A circuit having a single TRANSISTOR amplifier does not provide suitable bandwidth or gain. To OVERCOME this difficulty, we combine several amplification stages. The CASCADING transistor amplifier theory is used for high gain as well as high bandwidth.

Correct option is (C) LOW

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 low output impedance.

Right choice is (c) Voltage divider bias

Easy explanation: The SINGLE stage common emitter amplifier uses BIASING commonly called “Voltage Divider Biasing”. This type of biasing arrangement uses TWO resistors as a potential divider NETWORK across the supply with their center point supplying the REQUIRED Base bias voltage to the transistor.

Correct option is (a) it provides better voltage and current gain

The best EXPLANATION: The COMMON emitter configuration(CE) provides maximum voltage and current gain. The other configurations provide EITHER high current gain or voltage gain but not both for a BJT. That’s why CE amplifier is always preferred and HENCE does the choice of CE becomes obvious.

Correct answer is (a) True

The best explanation: The common BASE amplifier PLAN is very helpful in sound and radio recurrence applications because of its input yield impedance attributes. The CURRENT buffer is utilized to COORDINATE a low-impedance source to a high-impedance.

Right ANSWER is (b) to REDUCE the EFFECTS of r’e

The explanation is: A swamping resistor is an unbiased resistance in the emitter (re) circuit of a common-emitter amplifier. The swamping resistor stabilizes the voltage gain and reduces distortion.

The correct option is (a) 1

To ELABORATE: The CURRENT gain of a simplified CB amplifier configuration is approximately equal to unity (Ai ≈ 1). Ai is approximately equal to β / β + 1. The VALUE of β DEPENDS on the value of each individual transistors.

The correct choice is (b) hie + (1 + hfe) × RL

Explanation: The INPUT RESISTANCE of a simplified common collector (CC) amplifier can be expressed in terms of approximate HYBRID parameters. The input resistance is hie + (1 + hfe) × RLwhere, hie and hfe are the input resistance and CURRENT gain of CE amplifier respectively and RLis the load resistance.

Correct OPTION is (a) VB / VS

To explain: The overall voltage GAIN in a simplified common emitter hybrid model while considering RS is calculated as ratio of base voltage over the applied external voltage. It is expressed as VB / VS. Where, VS is the external applied voltage on the amplifier.

The correct answer is (B) -hfe

The explanation is: The current gain of a COMMON emitter (CE) amplifier can be EXPRESSED in TERMS of hybrid parameters in the simplified CE hybrid model. The current gain hfe is the forward transfer characteristics and is used to calculate the current gain in common emitter AMPLIFIERS.

The CORRECT answer is (d) 2.48dB

For explanation: The voltage gain in terms of decibels is EXPRESSED as 20 × LOG (Voutput / Vinput) . Given, Voutput = 20V and Vinput = 15V.

Voltage gain = 20 × log (Voutput / Vinput) = 20 × log (1.33) = 20 × 0.1239 = 2.48dB.

Right option is (c) 23.87

To elaborate: The TOTAL gain of a cascading transistor amplifier can be calculated by TAKING the product of the individual STAGES. Where,

AV = AV1 × AV2 × AV3 × AV4 = 1.5 × 2.3 × 3.46 × 2 = 23.87

Right option is (c) 2

To explain: An n-stage cascading amplifier is a two-port network assembled from a series of amplifiers. Each amplifier directs its OUTPUT to the input of the subsequent amplifier. The performance obtained from a single-stage amplifier is INADEQUATE, there FORE numerous stages are COMBINED to FORM a multistage amplifier.

Correct choice is (d) 2.32V

The explanation: The voltage VB of a simplified common BASE AMPLIFIER configuration can be calculated using VB = I × R2. GIVEN, VCC = 12V and R1 = 25kΩ and R2 = 6kΩ:

I = VCC / R1 + R2 = 12 / (25 + 6) = 0.387mA

VB = I × R2 = 0.387mA × 6kΩ = 2.32V

Right answer is (d) 1 – HIE / Ri

For EXPLANATION I would say: The voltage gain of as implified common collector (CC) amplifier can be EXPRESSED in terms of APPROXIMATE hybrid parameters. The voltage gain is equal to 1 – hie / Riwhere, Riis equal to hie + (1 + HFE) × RL .

Right choice is (c) 50dB

Easy explanation: The TOTAL gain of a cascading transistor amplifier is the SUM of the multiple STAGES when the gain is calculated is DECIBELS. Given, AV1 = 14dB, AV2 = 12dB and AV3 = 24dB

AV = AV1 + AV2 + AV3 = 14dB + 12dB + 24dB = 50dB

The correct option is (c) AV × AI

To explain I would say: The power GAIN in a simplified COMMON emitter hybrid model is calculated as the product of voltage gain and power gain. It is expressed as AV × AI. It can also be further simplified as AI^2 × RL / Ri, where RL is load resistance and Ri is INPUT resistance.

Correct ANSWER is (a) Increase voltage gain

Easy explanation: A circuit having a single transistor AMPLIFIER does not provide SUITABLE bandwidth or gain. The PURPOSE of an n-stage cascading amplifier is to provide an increase in the voltage gain. The total gain of ann-stage cascading amplifier is the product of the voltage gains of the discrete stages.

The CORRECT CHOICE is (d) 0.02mA

Easiest EXPLANATION: IC=V ACROSS RL/RL=5V/5KΩ=1mA

IB=IC/β=1/50=0.02MA.

Correct choice is (c) Current

To explain: The emitter FOLLOWER CONFIGURATION is prominently known for its feedback amplifier qualities. It is a NEGATIVE feedback network that provides a negative feedback of current to the CIRCUIT. It is generally used in the last STAGE of an amplifying network.

The correct OPTION is (a) True

The EXPLANATION: The symbols dBA, dBB and dBC are used for to estimated HUMAN ear’s reaction to sound. They all FALL under the subcategory of dB SPL which stands for sound pressure level. They are all weighted MEASURES and are used to refer to the effects of noise on human and animals’ ears.

Correct option is (c) Emitter

Easiest EXPLANATION: The n-stage cascading transistor amplifier circuit can be CONSTRUCTED by connecting the emitters of TWO consecutive transistors. A resistor is placed between each stage to act as a coupling DEVICE.

The correct option is (a) True

To elaborate: A coupling capacitor allows ac SIGNAL to PASS from ONE circuit to the other. This technique helps to isolate the DC bias SETTINGS of the two coupled circuits.

Right answer is (a) to increase voltage gain

For explanation I would say: When an EMITTER resistance is added in a CE amplifier, its voltage gain is REDUCED, but the input impedance increases. WHENEVER bypass capacitor is linked in PARALLEL with an emitter resistance, the voltage gain of CE amplifier increases.

Right answer is (d) RC / re‘

The best explanation: The voltage gain of a simplified COMMON base (CB) amplifier can be expressed in terms circuit RESISTOR values. The base impedance is RC / re‘. Where RC is the equivalent CURRENT resistance and re‘ is the ALTERNATING current resistance of the emitter-base diode.

The CORRECT choice is (a) 1

The explanation: The voltage gain of a simplified CC amplifier configuration is approximately equal to UNITY (AV ≈ 1) and its current gain, Ai is approximately equal to β(Ai ≈ β) which depends on the value of each individual TRANSISTORS.

Right option is (a) True

To explain I would SAY: It is more practical to calculate the approximate VALUES of voltage and current gains instead of computing the EXACT values of a common emitter amplifier circuit. We use a simplified common emitter hybrid model to OBTAIN these approximate values WITHOUT reducing the accuracy.

The correct answer is (a) DB

Easiest EXPLANATION: The decibel is a comparative UNIT of measurement equivalent to ONE tenth (deci) of a Bel unit. A Bel unit is expressed as B and hence the decibel is subsequently expressed by the SYMBOL dB. They are a unit of a logarithmic scale to measure power or intensity levels.

The correct choice is (d) Impedance matching

Easy explanation: The high input impedance and resistance along with low output impedance makes the transistor amplifier circuit amplifier ideal for impedance matching. Along with that, its key CHARACTERISTICS include a comparatively high CURRENT and POWER GAIN.

Correct choice is (c) emitter follower

The BEST EXPLANATION: The emitter follower configuration is mostly used as a VOLTAGE buffer. These configurations are EXTENSIVELY used in impedance matching applications because of their high input impedance.

Correct choice is (d) RB || β × (Re + re‘)

To explain I would say: The INPUT impedance of a simplified common collector (CC) amplifier can be expressed in TERMS circuit RESISTOR values. The base impedance is RB || β × (Re + re‘) . Where β is the transistor amplifiers current gain, Reis the equivalent emitter resistance, RB is the equivalent base resistance and re‘ is the alternating current resistance of the emitter-base diode.

The CORRECT option is (c) Amplitude of a signal

The explanation is: We use dBm to measure the POWER relative to 1mW. It is generally compared relative to a 600Ω IMPEDANCE, which EQUATES to a voltage level of 0.775V. The m stands for milliwatts. The DERIVATE dBm0 stands for dBm measured at zero transmission level point.

Correct choice is (c) RE || (re‘ + (R1 || R2) / (β + 1))

Easiest explanation: The output IMPEDANCE of a simplified common collector (CC) AMPLIFIER can be expressed in terms circuit resistor values. The base impedance is RE || (re‘ + (R1 || R2) / (β + 1)) . 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 (b) 4

To explain I would say: 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.

The correct option is (b) 180 degrees

To explain I would say: The negative ALTERNATION of an AC signal will CAUSE a decrease in the base current.This action then causes a CORRESPONDING decrease in EMITTER current through RL(load). The output signal of a common- emitter AMPLIFIER is therefore 180 degrees out of phase with the input signal.

The correct CHOICE is (c) Current

The explanation is: A HIGH input resistance transistor amplifier circuit configuration is PROMINENTLY known for its feedback amplifier qualities. It is a negative feedback network that provides a negative feedback of current to the circuit. It is generally used in the last STAGE of an AMPLIFYING network.

Right OPTION is (c) LOW

The explanation is: 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 low output impedance.