Analog Electronics Chapter 2: Exploring Inverting and Non-Inverting OPAMPs

OPAMP as Inverting Amplifier

The inverting amplifier configuration is one of the most common and widely used configurations of an operational amplifier (OPAMP). In this setup, the input signal is applied to the inverting terminal, and the non-inverting terminal is grounded. Let’s break down the diagram and understand the workings of this circuit in detail, along with formulas, the concept of virtual ground, and key characteristics.

Circuit Overview

Inverting Terminal (-): The input voltage (Vin) is applied to the inverting terminal through a resistor Rin.
Non-Inverting Terminal (+): The non-inverting terminal is connected to ground, creating a reference point for the operational amplifier.
Feedback Resistor (Rf): A resistor is placed between the output (Vo) and the inverting terminal, allowing feedback of a portion of the output signal back to the input.
Virtual Ground: Even though the non-inverting terminal is connected to ground (0V), due to the nature of the OPAMP, the voltage at the inverting terminal also behaves as if it were at 0V, creating what is called a “virtual ground.” This is explained in detail later.