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Questions and Answers
What is the primary function of an emitter follower in a circuit?
Which configuration is typically used for an emitter follower?
What is the typical voltage drop across the base-emitter junction of silicon transistors in an emitter follower?
What type of input impedance does an emitter follower have?
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What defines the phase relationship between the input and output signals of an emitter follower?
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Which of the following is a disadvantage of using an emitter follower?
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In which application is an emitter follower particularly useful?
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What is the current gain in an emitter follower circuit primarily dependent on?
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Which type of transistor is primarily used in an emitter follower configuration?
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What is one of the advantages of using an emitter follower?
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What is the main disadvantage of a direct coupled amplifier?
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What is the primary purpose of cascade amplifiers?
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Why is the cascade amplifier beneficial for high gains?
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What is one of the main applications of a direct coupled amplifier?
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What role do the transistors T1 and T2 play in a direct coupled amplifier?
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What happens to the bandwidth of a cascade amplifier as the number of stages increases?
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Which configuration is known for good high-frequency operation in cascade amplifiers?
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What issue arises due to non-perfect coupling between cascaded stages in amplifiers?
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Which of these does a cascade amplifier NOT typically enhance?
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What is one advantage of using a direct coupled amplifier?
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What is a primary advantage of using a Darlington emitter follower?
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Which statement accurately describes the voltage drop in a Darlington emitter follower?
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What are typical applications of a Darlington emitter follower?
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What is a limitation of the Darlington configuration?
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What is the primary function of the capacitor C2 in a bootstrap emitter follower?
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How does the current gain of a Darlington pair relate to the individual transistors?
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Which component is primarily responsible for bootstrapping in a bootstrap emitter follower?
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In a bootstrap emitter follower, which resistors are used for biasing the transistor?
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A common application for bootstrapped circuits includes:
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What is one of the essential design steps for creating a bootstrap emitter follower?
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What happens to the total gain in a multistage amplifier compared to the product of the individual stage gains?
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How is the voltage gain affected at low frequencies for an RC coupled amplifier?
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What characteristic of a coupling transformer in a transformer coupled amplifier helps in impedance matching?
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At high frequencies, how does a capacitor behave in the context of a transformer coupled amplifier?
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In an RC coupled amplifier, what factor contributes to the gain remaining constant in the mid-frequency range?
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What is the primary drawback of an RC coupled amplifier?
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What does the frequency response curve for an RC coupled amplifier generally indicate for frequencies outside the range of 50 Hz to 20 KHz?
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What does the primary of a transformer do in a transformer coupled amplifier?
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What role does the emitter bypass capacitor play in a transformer coupled amplifier?
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What happens to the effective load resistance when an amplifier's low output impedance is coupled to a high input impedance?
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Study Notes
Emitter Follower
- An emitter follower is a transistor amplifier circuit where the output is taken from the emitter terminal.
- The voltage gain is slightly less than 1.
- The output voltage follows the input voltage but with a voltage drop due to the base-emitter junction (typically around 0.7V for silicon transistors).
- The current gain is high, determined by the transistor's current gain (ß).
- High input impedance makes it good for buffering applications.
- Low output impedance allows it to drive low impedance loads effectively.
- Applications include: buffering, impedance matching, voltage regulation, and signal amplification.
Darlington Emitter Follower
- A Darlington emitter follower uses two transistors connected to act as a single transistor with a very high current gain.
- The base of the first transistor is connected to the emitter of the second transistor.
- The total voltage drop from the input to the output is approximately 1.4V (0.7V for each transistor).
- Current gain is the product of the individual transistor current gains.
- Applications include: buffer amplifiers, power amplifiers, and high-current switching.
Bootstrap Emitter Follower
- Improves the performance of a basic emitter follower by using bootstrapping.
- Increases input impedance and overall performance of the circuit.
- Uses a capacitor to create feedback, effectively raising the input impedance.
- Advantages include improved signal handling and increased impedance matching of high-impedance sources.
RC Coupled Amplifier
- Uses capacitors to couple the output of one stage to the input of the next stage.
- The gain is constant in mid-frequency range, decreases at low and high frequencies due to capacitor reactance.
- Low frequencies: high reactance, load effect and gain reduction.
- High frequencies: low reactance, load effect, and gain reduction.
Transformer Coupled Amplifier
- Uses a transformer to couple the output of one stage to the input of the next stage.
- Provides good impedance matching between amplifier stages.
- Advantage over RC coupled amplifier: overcomes the issue of reduced load resistance by impeding the load resistance to higher for the previous stage.
- Used for power amplifications.
- Low frequencies: reactance decreases, gain reduction.
- High frequencies: capacitance between windings acts as bypass condenser, gain reduction.
Direct Coupled Amplifier
- The stages are coupled directly, no coupling devices used.
- Uses alternating NPN and PNP transistors to minimize drift due to temperature variations.
- Simple circuit arrangement and low cost.
- Cannot be used for high frequency amplifications.
- Applications include low frequency and low current amplifications.
Cascade Amplifier
- A combination of multiple amplifier stages connected in series.
- Each stage's output is connected to the next stage's input.
- Used to achieve high gain and bandwidth.
- Provides high isolation between input and output.
- Applications: tuned RF amplifiers, wideband amplifiers, and high isolation applications.
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Description
This quiz explores the concepts of emitter follower and Darlington emitter follower circuits in transistor technology. It covers their characteristics, operational principles, and applications. Gain insights into how these amplifiers function and their significance in electronics.
