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LX2 > L2 - Identification of Transistor Amplifier Circuits > Flashcards

L2 - Identification of Transistor Amplifier Circuits Flashcards

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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
The Current Mirror Circuit effectively acts as a ___________
Constant current source
26
One of the key features of the current mirror circuit is it only uses two transistors
Simple Design
27
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.
Proportionally
28
Why are current mirrors used in analog ICs
Stable current needs to be distributed across different parts
29
Current mirrors can be used as ____ to improve gain of amplifier stages by providing a high-impedance load
Active loads
30
Applications of Current Mirror Circuits
1. Analog ICs 2. Amplifiers 3. Active Loads 4. Current Sources / Sinks
31
Type of Current Mirror that uses two identical transistors and mirrors the current exactly.
Basic Current Mirror
32
An improved version of the CM that provides better accuracy and higher output resistance, reducing the effect of variations in transistor properties
Wilson CM
33
Type of CM that provides high output impedance and improved voltage regulation
Cascode CM
34
Type of CM that allows for scaling of currents without requiring large resistors or components
Widlar CM
35
This configuration amplifies the difference between two input voltages
Differential Amplifier
36
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
Common-mode (High CMRR)
37
The two transistors share a common current source, which helps ________ the operation of the circuit
balance
38
The differential pair provides a ______ response to small differences in input voltage, making it ideal for amplification.
Linear
39
Differential pair offers good temperature ________
Stability
40
Since the differential pair operate in a balanced manner, it has ___________ distortion
low harmonic
41
The outputs of diff amps with resistive load are usually taken from the _____
collector
42
It is called an operational amplifier because......
It can perform some mathematical operations
43
Main difference of Op-Amp to Diff-Amp
Very high open loop gain
44
Three stages of an Op-Amp
1. Diff Amp stage 2. Additional amplifier stage 3. Output Stage (Voltage Follower)
45
Op-Amp has ____ inputs and ___ outputs
Two; One
46
In Op-Amps; Vin1 is called
noninverting input
47
In Op-Amps; Vin2 is called
Inverting input
48
Three bands of the frequency response
1. Passband 2. Transition Band 3. Stopband
49
It allows low-frequency signals to pass while rejecting high-frequency signals.
Low Pass Filter
50
It allows high-frequency signals to pass and reject low-frequency signals
High Pass Filter
51
This kind of filter rejects both low and high-frequency signals and passes a band in between.
Band Pass Filter
52
This kind of filter passes both low and high-frequency signals and rejects the band in between.
Band Reject Filter
53
It is a filter composed of circuit elements such as resistors, capacitors, and inductors
Continuous-Time
54
A filter is mainly composed of energy storage elements such as a capacitor and a switch.
Discrete-Time
55
It is a filter that incorporates only passive devices.
Passive Filter
56
A filter that employs amplifying components.
Active Filter
57
Refers to a filter circuit made up of passive components that has a frequency response defined by a first-order differential equation.
First-order passive filter
58
These filters are called "first-order" because their roll-off rate is _____________- in the stopband
20dB per decade; 6dB per octave
59
First-order passive filters can be configured as ________
low-pass or high-pass filters
60
For a first-order passive low-pass filter, the output is taken across the ________
capacitor
61
For a first-order passive high-pass filter, the output is taken across the ______
resistor
62
To construct an active filter circuit, ______ into a second stage active circuit
cascade a first-stage passive filter
63
To construct an active filter is to use frequency-dependent components in the _______________ of an amplifier
feedback network
64
It is typically composed of two frequency-dependent components.
Second-Order Filters
65
For Second-Order Filters, a passive filter is typically composed of ______
Resistor, Inductor, Capacitor
66
For second-order active filters, this is typically used.
Sallen-Key Filter
67
Sallen-Key Filters uses __________ for the two frequency-dependent components
two capacitors
68
The simplest way to implement a band pass filter
Cascade a LPF and a HPF
69
In cascading an LPF and an HPF to make a BPF, what is the requirement for the cutoff frequencies?
fchpg < fclpf
70
Cascading an LPF and an HPF to make a BPF is only suitable for ________
wideband applications
71
A passive narrowband BPF can be implemented using _______
passive elements
72
An active narrowband BPF is implemented using ______
Multiple Feedback Filter
73
It is widely used as a power amplifier due to its high current gain, low output impedance, and ability to drive heavy loads.
Emitter Follower / Common-Collector
74
A type of amplifier design where two active devices alternately handle the positive and negative halves of the input signal
Push-Pull
75
Push-pull amplifier is commonly used in audio and radio frequency applications due to its ___________
efficiency and ability to deliver significant output power
76
The push-pull amplifier achieves higher efficiency because each transistor is only active for ______, reducing ________
half the cycle, power dissipation
77
It is a form of distortion that occurs when neither transistor is conducting during the transition between signal halves.
Crossover distortion
78
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.
tied together; turn ON
79
Distortion in a push-pull stage can be solved by _____
introducing a DC voltage source in between the two base terminals
80
In an improved push-pull stage amplifier, the circuit operates in this way to reduce crossover distortion while maintaining high efficiency.
Class AB
81
The improved push-pull amplifier typically uses _________ which allows for symmetrical amplification
complementary transistors
82
Each transistor is conducting for the whole cycle with a conduction angle of 360
Class A
83
Each transistor is conducting for half the cycle with a conduction angle of 180
Class B
84
Each transistor is conducting slightly greater than half the cycle with a conduction angle slightly greater than 180
Class AB
85
With the less conduction angle
Higher efficiency
86
A transistor with a conduction angle less than 360 is prone to produce ________ in the output hence reducing the ______ of the amplifier.
distortions; linearity
87
The ratio of the center frequency to the bandwidth
Quality factor

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