An inverting amplifier is a type of operational amplifier (op-amp) configuration that produces an inverted output voltage with respect to the input voltage. It is commonly used in analog electronics to amplify an input signal while inverting its polarity. The inverting amplifier circuit is straightforward and consists of an op-amp and two resistors: a feedback resistor (Rf) and an input resistor (Rin).
The circuit diagram of an inverting amplifier is as follows:
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+Vcc +Vout
| |
| |
Rf |
| +-----|-----+
Vin ---|---Rin---| | | |
| | | Rf |
| | | | |
+---------+-----|-----|-----|---- GND
| | | |
+-----+-----+-----+
|
-
Here:
Vin: Input voltage applied to the input terminal of the inverting amplifier.
Vout: Output voltage taken from the output terminal of the inverting amplifier.
Rf: Feedback resistor, connected between the output terminal and the inverting input terminal (marked with a minus sign).
Rin: Input resistor, connected between the inverting input terminal and the Vin input.
The gain (A) of the inverting amplifier is calculated using the following formula:
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A = -Rf / Rin
The negative sign in the gain equation indicates that the output voltage is inverted compared to the input voltage. The magnitude of the gain depends on the ratio of the feedback resistor (Rf) to the input resistor (Rin). The gain can be adjusted by choosing appropriate values for these resistors.
It is essential to note that for ideal op-amps, the gain is theoretically infinite. However, in practical circuits, real op-amps have limitations and are often powered by a finite voltage supply (±Vcc). As a result, the gain is typically determined by the ratio of the resistors within the available supply voltage range to prevent clipping and saturation of the output signal.