Inverting amplifier is one of the most popular Operational Amplifier circuits. The output changes in such a way that tries to avoid saturation and counteract the change caused by the input. This makes the amplifier stable. The amplifier tries to resist change and so avoid saturation. As the open loop DC gain of an operational amplifier is extremely high,
we can therefore afford to lose some of this gain by connecting a suitable resistor across the amplifier from the output terminal back to the inverting input terminal to both reduce and control the overall gain of the amplifier. This produces a very stable Operational Amplifier based system. The polarity of input voltage gets inverted at the output. If a sine wave is fed to the input of this amplifier, the output will be amplified sine wave with 180° phase shift.It has so many applications for example Audio amplifier, Pre amplifier, etc.
we can therefore afford to lose some of this gain by connecting a suitable resistor across the amplifier from the output terminal back to the inverting input terminal to both reduce and control the overall gain of the amplifier. This produces a very stable Operational Amplifier based system. The polarity of input voltage gets inverted at the output. If a sine wave is fed to the input of this amplifier, the output will be amplified sine wave with 180° phase shift.It has so many applications for example Audio amplifier, Pre amplifier, etc.
Circuit Diagram of Inverting Amplifier
Components Required
- 741 Op Amp
- Resistors(10kΩ,2kΩ)
Output waveform
Blue = Input
Red = Output
Working of Inverting Amplifier
- The non-inverting input is held at 0v
- The feedback will try to ensure that the inverting input is very close to 0v. This is because the difference between the inputs must be only µV if the output is not saturated. The inverting input is called a virtual ground.
- The resistors form a potential divider with the center at 0v
- Assume that Vin is 0v. Thus Vout must also be 0v
- If Vin rises then the inverting input is greater than non-inverting and so Vout goes rapidly negative until the two inputs are once again equal (or at least only µV's different)
- Similarly, if Vin goes negative then the inverting input is less than non-inverting input and so Vout rises rapidly to become positive.
- For the amplifier to work properly the output must be able to change very quickly in order to react to the changes in the input. This limits the maximum frequency at which the amplifier can operate.
- The ratio of Vin and Vout depends on the ratio of the resistors in the potential divider and so, at low frequencies, the gain depends only on the values of Rf and Ri.
- At higher frequencies the gain of the op-amp is limited and so sets an upper limit on the gain of the amplifier circuit.
Design
Components Pin out
i-St@r Lab
Simulated output using Multisim
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