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LX2 > L2 - Identification of Transistor Amplifier Circuits > Flashcards

L2 - Identification of Transistor Amplifier Circuits Flashcards

1
Q

Consists of two BJT transistors where the emitter of one is connected to the base of the other

A

Darlington Pair

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2
Q

The typical beta of a Darlington pair is

A

> 1000

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3
Q

What does the Darlington pair produce when the two transistors act as one?

A

Superbeta transistor

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4
Q

The current gain or beta of the Darlington pair is the _______ of the two current gains.

A

Product

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5
Q

Darlington pair requires _______ input current to control a large output current, making it useful in applications where power needs to be amplified.

A

Very Little

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6
Q

Darlington pair has a _____ saturation voltage as the voltage drop is the _____ of the Vbes of the two transistors

A

Higher; Sum

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7
Q

The Darlington pair is similar to that of an _____ transistor

A

Emitter Follower / Common Collector

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8
Q

Applications of Darlington Pair

A
  1. Power Amplifier
  2. Switching Applications
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9
Q

It utilizes one NPN and one PNP where the NPN’s collector is connected to the PNP’s base.

A

Complementary Feedback / Sziklai Pair

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10
Q

The current gain of the Sziklai pair is approximately the _____ of the gains of the individual transistors.

A

Product

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11
Q

The Sziklai pair has a ______ saturation voltage which has a value closer to ______.

A

Lower; 0.2-0.3 V

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12
Q

The complementary transistors created a ________ that helps stabilize the pair and reduce distortion.

A

Feedback loop

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13
Q

Applications of Sziklai Pair

A
  1. Audio Amplifiers
  2. Switching Applications
  3. Voltage Regulators
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14
Q

The Sziklai pair generally has a _____ response time compared to the Darlington pair

A

Faster

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15
Q

Both Darlington and Sziklai pair are mainly used as _____

A

current amplifiers

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16
Q

It is done by connecting two transistors in a series

A

Cascoding

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17
Q

Transistor cascoding is usually implemented to improve an amplifier’s ____________

A

output impedance

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18
Q

The higher the output impedance

A

The higher the gain

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19
Q

Cascode configuration are _______ in series

A

stacked

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20
Q

The lower transistor is known as the _______________

A

Amplifying transistor

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21
Q

The upper transistor is the _______

A

Cascode transistor

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22
Q

A cascoded configuration is set to be a _____

A

common source circuit

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23
Q

An analog circuit designed to copy or replicate the current flowing through one active device into another

A

Current Mirror Circuit

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24
Q

The current mirror circuit makes a perfect copy by _______________ in the output device as in the reference device.

A

maintaining the reference current

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25
Q

The Current Mirror Circuit effectively acts as a ___________

A

Constant current source

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26
Q

One of the key features of the current mirror circuit is it only uses two transistors

A

Simple Design

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27
Q

In more advanced Current Mirror Circuits, the current in the output can be scaled ________ to the reference current by adjusting transistor sizes or resistor values.

A

Proportionally

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28
Q

Why are current mirrors used in analog ICs

A

Stable current needs to be distributed across different parts

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29
Q

Current mirrors can be used as ____ to improve gain of amplifier stages by providing a high-impedance load

A

Active loads

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30
Q

Applications of Current Mirror Circuits

A
  1. Analog ICs
  2. Amplifiers
  3. Active Loads
  4. Current Sources / Sinks
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31
Q

Type of Current Mirror that uses two identical transistors and mirrors the current exactly.

A

Basic Current Mirror

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32
Q

An improved version of the CM that provides better accuracy and higher output resistance, reducing the effect of variations in transistor properties

A

Wilson CM

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33
Q

Type of CM that provides high output impedance and improved voltage regulation

A

Cascode CM

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34
Q

Type of CM that allows for scaling of currents without requiring large resistors or components

A

Widlar CM

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35
Q

This configuration amplifies the difference between two input voltages

A

Differential Amplifier

36
Q

The differential pair has high ______ rejection, meaning it can ignore or reject signals that are common to both inputs and only respond to the difference

A

Common-mode (High CMRR)

37
Q

The two transistors share a common current source, which helps ________ the operation of the circuit

A

balance

38
Q

The differential pair provides a ______ response to small differences in input voltage, making it ideal for amplification.

A

Linear

39
Q

Differential pair offers good temperature ________

A

Stability

40
Q

Since the differential pair operate in a balanced manner, it has ___________ distortion

A

low harmonic

41
Q

The outputs of diff amps with resistive load are usually taken from the _____

A

collector

42
Q

It is called an operational amplifier because……

A

It can perform some mathematical operations

43
Q

Main difference of Op-Amp to Diff-Amp

A

Very high open loop gain

44
Q

Three stages of an Op-Amp

A
  1. Diff Amp stage
  2. Additional amplifier stage
  3. Output Stage (Voltage Follower)
45
Q

Op-Amp has ____ inputs and ___ outputs

A

Two; One

46
Q

In Op-Amps; Vin1 is called

A

noninverting input

47
Q

In Op-Amps; Vin2 is called

A

Inverting input

48
Q

Three bands of the frequency response

A
  1. Passband
  2. Transition Band
  3. Stopband
49
Q

It allows low-frequency signals to pass while rejecting high-frequency signals.

A

Low Pass Filter

50
Q

It allows high-frequency signals to pass and reject low-frequency signals

A

High Pass Filter

51
Q

This kind of filter rejects both low and high-frequency signals and passes a band in between.

A

Band Pass Filter

52
Q

This kind of filter passes both low and high-frequency signals and rejects the band in between.

A

Band Reject Filter

53
Q

It is a filter composed of circuit elements such as resistors, capacitors, and inductors

A

Continuous-Time

54
Q

A filter is mainly composed of energy storage elements such as a capacitor and a switch.

A

Discrete-Time

55
Q

It is a filter that incorporates only passive devices.

A

Passive Filter

56
Q

A filter that employs amplifying components.

A

Active Filter

57
Q

Refers to a filter circuit made up of passive components that has a frequency response defined by a first-order differential equation.

A

First-order passive filter

58
Q

These filters are called “first-order” because their roll-off rate is _____________- in the stopband

A

20dB per decade; 6dB per octave

59
Q

First-order passive filters can be configured as ________

A

low-pass or high-pass filters

60
Q

For a first-order passive low-pass filter, the output is taken across the ________

A

capacitor

61
Q

For a first-order passive high-pass filter, the output is taken across the ______

A

resistor

62
Q

To construct an active filter circuit, ______ into a second stage active circuit

A

cascade a first-stage passive filter

63
Q

To construct an active filter is to use frequency-dependent components in the _______________ of an amplifier

A

feedback network

64
Q

It is typically composed of two frequency-dependent components.

A

Second-Order Filters

65
Q

For Second-Order Filters, a passive filter is typically composed of ______

A

Resistor, Inductor, Capacitor

66
Q

For second-order active filters, this is typically used.

A

Sallen-Key Filter

67
Q

Sallen-Key Filters uses __________ for the two frequency-dependent components

A

two capacitors

68
Q

The simplest way to implement a band pass filter

A

Cascade a LPF and a HPF

69
Q

In cascading an LPF and an HPF to make a BPF, what is the requirement for the cutoff frequencies?

A

fchpg < fclpf

70
Q

Cascading an LPF and an HPF to make a BPF is only suitable for ________

A

wideband applications

71
Q

A passive narrowband BPF can be implemented using _______

A

passive elements

72
Q

An active narrowband BPF is implemented using ______

A

Multiple Feedback Filter

73
Q

It is widely used as a power amplifier due to its high current gain, low output impedance, and ability to drive heavy loads.

A

Emitter Follower / Common-Collector

74
Q

A type of amplifier design where two active devices alternately handle the positive and negative halves of the input signal

A

Push-Pull

75
Q

Push-pull amplifier is commonly used in audio and radio frequency applications due to its ___________

A

efficiency and ability to deliver significant output power

76
Q

The push-pull amplifier achieves higher efficiency because each transistor is only active for ______, reducing ________

A

half the cycle, power dissipation

77
Q

It is a form of distortion that occurs when neither transistor is conducting during the transition between signal halves.

A

Crossover distortion

78
Q

For a push-pull stage, the distortion arises from the input connection since both base terminals are ______, thus the two transistors cannot _______ around Vin = 0V.

A

tied together; turn ON

79
Q

Distortion in a push-pull stage can be solved by _____

A

introducing a DC voltage source in between the two base terminals

80
Q

In an improved push-pull stage amplifier, the circuit operates in this way to reduce crossover distortion while maintaining high efficiency.

A

Class AB

81
Q

The improved push-pull amplifier typically uses _________ which allows for symmetrical amplification

A

complementary transistors

82
Q

Each transistor is conducting for the whole cycle with a conduction angle of 360

A

Class A

83
Q

Each transistor is conducting for half the cycle with a conduction angle of 180

A

Class B

84
Q

Each transistor is conducting slightly greater than half the cycle with a conduction angle slightly greater than 180

A

Class AB

85
Q

With the less conduction angle

A

Higher efficiency

86
Q

A transistor with a conduction angle less than 360 is prone to produce ________ in the output hence reducing the ______ of the amplifier.

A

distortions; linearity

87
Q

The ratio of the center frequency to the bandwidth

A

Quality factor

LX2 (2 decks)

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