Question

Match the following

i–iv	Connection Type	a–d	Feedback Description
i	Voltage shunt	a	Current sampling, voltage mixing
ii	Voltage series	b	Current sampling, current mixing
iii	Current shunt	c	Voltage sampling, current mixing
iv	Current series	d	Voltage sampling, voltage mixing

• A. i-b, ii-a, iii-c, iv-d
• B. i-c, ii-b, iii-d, iv-a
• C. i-a, ii-d, iii-b, iv-c
• D. i-d, ii-c, iii-a, iv-b

Hint:

Feedback Topology Naming: (Type of Output Signal Sampled) - (Way Feedback is Mixed at Input).
Voltage Sampling: Feedback network connected in shunt (parallel) across the output.
Current Sampling: Feedback network connected in series with the output (load).
Shunt Mixing (Current Mixing): Feedback signal (current) summed with input current source in parallel at input.
Series Mixing (Voltage Mixing): Feedback signal (voltage) summed with input voltage source in series at input.
Voltage Shunt (Shunt-Shunt): Samples V\(_o\), mixes I\(_f\) with I\(_s\). (Voltage sampling, Current mixing).
Voltage Series (Series-Shunt): Samples V\(_o\), mixes V\(_f\) with V\(_s\). (Voltage sampling, Voltage mixing).
Current Shunt (Shunt-Series): Samples I\(_o\), mixes I\(_f\) with I\(_s\). (Current sampling, Current mixing).
Current Series (Series-Series): Samples I\(_o\), mixes V\(_f\) with V\(_s\). (Current sampling, Voltage mixing).

Answer 1

The Correct Option is C

Feedback Amplifier Matching

The terminology for feedback amplifiers is based on two parts:

• Output Sampling: "Voltage" or "Current" sampling
• Input Mixing: "Series" or "Shunt" mixing

Interpretations:

• Voltage Sampling: Feedback network in parallel (shunt) with the output.
• Current Sampling: Feedback network in series with the output.
• Shunt Mixing: Feedback current added in parallel to input current (current mixing).
• Series Mixing: Feedback voltage added in series to input source (voltage mixing).

Matching Feedback Types to Characteristics

Feedback Type	Sampling	Mixing	Description
i. Voltage Shunt	Voltage	Current	Voltage Sampling, Current Mixing → (c)
ii. Voltage Series	Voltage	Voltage	Voltage Sampling, Voltage Mixing → (d)
iii. Current Shunt	Current	Current	Current Sampling, Current Mixing → (b)
iv. Current Series	Current	Voltage	Current Sampling, Voltage Mixing → (a)

So the correct matching is:

\[ \boxed{ \text{i} \rightarrow \text{c},\quad \text{ii} \rightarrow \text{d},\quad \text{iii} \rightarrow \text{b},\quad \text{iv} \rightarrow \text{a} } \]

Final Answer: Option (b) matches this combination correctly. The checkmark shown on option (3) in the image (i-a, ii-d, iii-b, iv-c) is incorrect, as it mismatches the type of sampling and mixing for voltage shunt and current series feedback types.