Question

Find the block diagram representation of non-inverting amplifier with feedback?

I have been asked this question in final exam.

I'm obligated to ask this question of Voltage Series Feedback Amplifier in section Operational Amplifier Characteristics of Linear Integrated Circuits

Answer 1

The block diagram representation of a non-inverting amplifier with feedback is as follows:

• Input signal (V_in) is applied to the non-inverting input (+) of the operational amplifier (op-amp).
• A feedback network is connected between the output of the op-amp and the non-inverting input (+).
• The inverting input (−) is typically grounded or connected to the feedback network.
• The output signal (V_out) is taken from the output terminal of the op-amp.

Block Diagram Representation:

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+---------------------+ | | V_in --->| (+) |---> V_out | | Feedback |<---- R_f ---> | | | | | | | | (-) | +---------------------+

Explanation:

• V_in: The input signal applied to the non-inverting input of the op-amp.
• R_f: The feedback resistor, which is connected between the output and the non-inverting input.
• V_out: The output voltage of the op-amp.

The feedback loop maintains the gain of the amplifier, and for a non-inverting amplifier, the relationship between the output voltage and the input voltage is defined by the equation:

Vout=Vin×(1+RfRin)V_{out} = V_{in} \times \left(1 + \frac{R_f}{R_{in}}\right)Vout​=Vin​×(1+Rin​Rf​​)

Where:

• RfR_fRf​ is the feedback resistor,
• RinR_{in}Rin​ is the input resistor connected between the inverting input and ground.

In this configuration, the signal at the output is in phase with the input, and the gain is greater than or equal to 1.