An inverting amplifier is a type of operational amplifier (op-amp) circuit that produces an output that is the opposite (inverted) polarity of the input signal. In other words, when the input voltage increases, the output voltage decreases, and vice versa.
The basic configuration of an inverting amplifier involves an operational amplifier with two input terminals, labeled as the inverting input (usually denoted with a minus sign, "-") and the non-inverting input (usually denoted with a plus sign, "+"). The input signal is applied to the inverting input terminal, and the output is taken from the output terminal of the op-amp.
The inverting amplifier circuit typically consists of a feedback resistor (Rf) connected between the output terminal and the inverting input, and an input resistor (Rin) connected between the inverting input and the input signal source. The non-inverting input is usually connected to a reference point (e.g., ground) through a resistor (Rg) to create a virtual ground, which helps in the amplification process.
The voltage gain (Av) of an inverting amplifier can be calculated using the following formula:
Av = - Rf / Rin
Where:
Av is the voltage gain (dimensionless).
Rf is the feedback resistor (in ohms) connected between the output and the inverting input of the op-amp.
Rin is the input resistor (in ohms) connected between the inverting input and the input signal source.
The negative sign in the voltage gain formula indicates the inversion of the input signal, which is characteristic of the inverting amplifier configuration. The magnitude of the voltage gain is determined by the ratio of the feedback resistor to the input resistor, and its value can be controlled by appropriately selecting the resistor values in the circuit.
Keep in mind that while the voltage gain formula is a simplified representation of an ideal inverting amplifier, in real-world applications, factors such as op-amp limitations, bandwidth, and other considerations should be taken into account for accurate design and analysis.