Department of Electronics and
Communication Engineering
23ECR406 ANALOG INTEGRATED CIRCUITS
CIA II ANSWERKEY
1 List the limitations of voltage to current converters CO 3 K1
Non-ideal behavior at high frequencies, potential for instability, and limited
current output.
2 What is active filter and specify the types of filters? CO 3 K1
A filter is designed to selectively allow or block certain frequencies. Common
filter types include low-pass, high-pass, band-pass, and band-reject (notch) filters.
3 In the low-pass filter shown in the figure, for a cut-off frequency CO 3 K3
of 5kHz, the value of R2 GAT
E
2014
4 Why active filters are preferred over the passive filters? CO 3 K2
Active filters have the following advantages over passive filters: (1) gain of the
active filter can be greater than one (2) active filters can be cascaded without
loading and impedance matching issues; (3) active filters can be constructed
without using inductors, which are bulky
5 Summarize the important features of an instrumentation amplifier. CO 3 K2
Very high common mode rejection ratio (CMRR), High open loop gain, Low DC
offset, Low drift, Low input impedance, and Low noise.
6 Differentiate the feature of voltage controlled oscillator (VCO) in K2
comparison with other oscillators. CO 4
A Voltage Controlled Oscillator (VCO) differs from other oscillators by
its ability to dynamically adjust its output frequency based on an applied
control voltage
7 List any two application of 555 Timer in Monostable mode. CO 4 K1
In monostable mode, the 555 timer can be used in applications like pulse
generation and delay circuits.
8 Illustrate the purpose of using an external pass transistor with an IC voltage K2
regulator. CO 5
An external pass transistor is used with an IC voltage regulator to increase the
output current capacity of the regulator, allowing it to handle heavier loads. It acts
as a "current booster," enabling the regulator to supply larger currents.
9 Differentiate linear and switching regulators. CO 5 K2
Linear regulators dissipate excess power as heat to maintain a stable output
voltage, while switching regulators use switching components (like transistors) to
, efficiently convert and regulate voltage
10 List the need for protection diodes in voltage regulators based on LM317 CO 5 K1
regulator.
Protection diodes in LM317 voltage regulators are used to prevent damage to the
internal transistors when the input voltage drops to zero while the output capacitor
is charged. They also help protect against reverse voltage.
11 (i)Explain in detail the function of amplifier with resistive load and active Load
Amplifier with resistive load
In a resistive load amplifier, a resistor (RL) is connected in series with the
amplifier's output to control the DC bias current and voltage.
The gain of the amplifier with a resistive load is determined by the resistance (RL)
and the amplifier's internal parameters (like transconductance, gm).
The gain is limited by the value of RL and the amplifier's internal resistance.
The output voltage swing is limited by the DC supply voltage and the voltage drop
across RL. Simple to design and implement, and provides stable operation.
A common-emitter amplifier with a collector resistor (RC) as the load.
The active load (e.g., current mirror) maintains a constant current regardless of the
output voltage, providing a high output resistance.
A common active load in amplifier circuits, especially for differential amplifiers.
Active loads are preferred in applications where high gain, large output swing, and
low distortion are required, especially in integrated circuits.
Amplifier with resistive load
Instead of a resistor, an active device (e.g., a transistor) is used as the load. This
active device acts as a current source, providing a high resistance for the amplifier's
output.
The gain is higher than with resistive loads due to the high output resistance of the
active load.
Higher gain, better output swing, and reduced distortion. More complex to design
and implement, and can be more sensitive to temperature variations. A differential
amplifier with a current mirror as the load
(ii)Sketch an instrumentation amplifier using three Op-Amp and derive its output
voltage equation.
The important features of an instrumentation amplifier are
1. High gain accuracy
2. High CMRR
3. High gain stability with low temperature coefficient
4. Low output impedance
Instrumentation amplifier is a kind of differential amplifier with additional input buffer
stages. The addition of input buffer stages makes it easy to match (impedance matching)
the amplifier with the preceding stage. Instrumentation amplifiers are commonly used in
industrial test and measurement application.
, 12 (i)Explain in detail the function of amplifier with depletion load and current source
load.
An amplifier with a depletion load, typically a depletion-mode MOSFET, amplifies a
signal by using the inherent conductivity of the depletion-mode transistor to provide a load
Depletion MOSFET as an Active Load
Depletion-mode MOSFETs can act as a constant current source because they conduct
current even without a gate voltage, making them a good choice for load resistors in logic
circuits or as a load in amplifiers. A depletion-mode MOSFET has a channel that conducts
current even without a gate voltage. The gate-to-source voltage can control the channel's
width and the amount of current flowing. In an amplifier, the depletion-mode MOSFET
acts as the load, providing the necessary current flow for amplification. The depletion-
mode MOSFET is biased to operate in its linear region, allowing the amplifier to amplify
the input signal.
Communication Engineering
23ECR406 ANALOG INTEGRATED CIRCUITS
CIA II ANSWERKEY
1 List the limitations of voltage to current converters CO 3 K1
Non-ideal behavior at high frequencies, potential for instability, and limited
current output.
2 What is active filter and specify the types of filters? CO 3 K1
A filter is designed to selectively allow or block certain frequencies. Common
filter types include low-pass, high-pass, band-pass, and band-reject (notch) filters.
3 In the low-pass filter shown in the figure, for a cut-off frequency CO 3 K3
of 5kHz, the value of R2 GAT
E
2014
4 Why active filters are preferred over the passive filters? CO 3 K2
Active filters have the following advantages over passive filters: (1) gain of the
active filter can be greater than one (2) active filters can be cascaded without
loading and impedance matching issues; (3) active filters can be constructed
without using inductors, which are bulky
5 Summarize the important features of an instrumentation amplifier. CO 3 K2
Very high common mode rejection ratio (CMRR), High open loop gain, Low DC
offset, Low drift, Low input impedance, and Low noise.
6 Differentiate the feature of voltage controlled oscillator (VCO) in K2
comparison with other oscillators. CO 4
A Voltage Controlled Oscillator (VCO) differs from other oscillators by
its ability to dynamically adjust its output frequency based on an applied
control voltage
7 List any two application of 555 Timer in Monostable mode. CO 4 K1
In monostable mode, the 555 timer can be used in applications like pulse
generation and delay circuits.
8 Illustrate the purpose of using an external pass transistor with an IC voltage K2
regulator. CO 5
An external pass transistor is used with an IC voltage regulator to increase the
output current capacity of the regulator, allowing it to handle heavier loads. It acts
as a "current booster," enabling the regulator to supply larger currents.
9 Differentiate linear and switching regulators. CO 5 K2
Linear regulators dissipate excess power as heat to maintain a stable output
voltage, while switching regulators use switching components (like transistors) to
, efficiently convert and regulate voltage
10 List the need for protection diodes in voltage regulators based on LM317 CO 5 K1
regulator.
Protection diodes in LM317 voltage regulators are used to prevent damage to the
internal transistors when the input voltage drops to zero while the output capacitor
is charged. They also help protect against reverse voltage.
11 (i)Explain in detail the function of amplifier with resistive load and active Load
Amplifier with resistive load
In a resistive load amplifier, a resistor (RL) is connected in series with the
amplifier's output to control the DC bias current and voltage.
The gain of the amplifier with a resistive load is determined by the resistance (RL)
and the amplifier's internal parameters (like transconductance, gm).
The gain is limited by the value of RL and the amplifier's internal resistance.
The output voltage swing is limited by the DC supply voltage and the voltage drop
across RL. Simple to design and implement, and provides stable operation.
A common-emitter amplifier with a collector resistor (RC) as the load.
The active load (e.g., current mirror) maintains a constant current regardless of the
output voltage, providing a high output resistance.
A common active load in amplifier circuits, especially for differential amplifiers.
Active loads are preferred in applications where high gain, large output swing, and
low distortion are required, especially in integrated circuits.
Amplifier with resistive load
Instead of a resistor, an active device (e.g., a transistor) is used as the load. This
active device acts as a current source, providing a high resistance for the amplifier's
output.
The gain is higher than with resistive loads due to the high output resistance of the
active load.
Higher gain, better output swing, and reduced distortion. More complex to design
and implement, and can be more sensitive to temperature variations. A differential
amplifier with a current mirror as the load
(ii)Sketch an instrumentation amplifier using three Op-Amp and derive its output
voltage equation.
The important features of an instrumentation amplifier are
1. High gain accuracy
2. High CMRR
3. High gain stability with low temperature coefficient
4. Low output impedance
Instrumentation amplifier is a kind of differential amplifier with additional input buffer
stages. The addition of input buffer stages makes it easy to match (impedance matching)
the amplifier with the preceding stage. Instrumentation amplifiers are commonly used in
industrial test and measurement application.
, 12 (i)Explain in detail the function of amplifier with depletion load and current source
load.
An amplifier with a depletion load, typically a depletion-mode MOSFET, amplifies a
signal by using the inherent conductivity of the depletion-mode transistor to provide a load
Depletion MOSFET as an Active Load
Depletion-mode MOSFETs can act as a constant current source because they conduct
current even without a gate voltage, making them a good choice for load resistors in logic
circuits or as a load in amplifiers. A depletion-mode MOSFET has a channel that conducts
current even without a gate voltage. The gate-to-source voltage can control the channel's
width and the amount of current flowing. In an amplifier, the depletion-mode MOSFET
acts as the load, providing the necessary current flow for amplification. The depletion-
mode MOSFET is biased to operate in its linear region, allowing the amplifier to amplify
the input signal.
