To find the AC inverting amplifier in the context of operational amplifier circuits, we need to focus on the configuration where the input signal is applied to the inverting terminal, and the non-inverting terminal is typically grounded (in AC applications).
The general characteristics of an AC inverting amplifier are as follows:
- Input signal is applied to the inverting input (VinV_{\text{in}}Vin) of the operational amplifier through a capacitor (for AC signals).
- The non-inverting input is connected to ground.
- The feedback resistor (RFR_FRF) is connected between the output and the inverting input.
- The input resistor (RinR_{\text{in}}Rin) is placed between the input signal and the inverting input.
- The gain of the circuit is given by the formula:
Gain (Av)=−RFRin\text{Gain (} A_{\text{v}} \text{)} = -\frac{R_F}{R_{\text{in}}}Gain (Av)=−RinRF
Steps to identify the AC inverting amplifier:
- AC coupling: In the case of an AC amplifier, a capacitor will typically be placed in series with the input signal to block any DC component and allow only AC signals to pass through.
- Inverting configuration: The input is applied to the inverting terminal of the op-amp, and the output is taken from the output terminal.
- Feedback resistor: A feedback resistor is used to control the gain, and the output voltage will be inverted and amplified based on the resistor values.
Common Characteristics in the Circuit:
- Input capacitor (CinC_{\text{in}}Cin) in series with RinR_{\text{in}}Rin.
- The output voltage will have a phase shift of 180° relative to the input.
- The gain is determined by the ratio of RFR_FRF to RinR_{\text{in}}Rin.
In summary, if you are looking for an AC inverting amplifier:
- Identify the circuit where an AC signal is fed to the inverting input via a capacitor.
- Look for a feedback resistor from the output to the inverting terminal.
- The circuit will have an inverted output, and the gain will be the negative ratio of RFR_FRF to RinR_{\text{in}}Rin.