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Preconfigured Amplifier Circuits
Popular Applications
Inverting Amplifier
AC-Coupled Inverting Amp
NonInverting Amp

Instrumentation & Signal Conditioning
Integrator

Preconfigured Active Filters
Lowpass Filter
Lowpass Filter 4th Order
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AC-Coupled Inverting Amp
Vout: The output voltage will be [(-Rf/Rg) x Vin(ac)] + Vbias. Rload: This resistor represents the actual load in your system. The default resistance is the value recommended for this op amp. If the load is greater than the op amp can handle, the simulation results will show a limited output voltage. V+ & V-: The total voltage between the V+ and V- pins is the op amp supply voltage. This supply voltage must be within the range specified for the chosen op amp. Op Amp: Amplifiers to be used in this design must meet the bandwidth requirements of the circuit, as well as the input voltage, output voltage, and supply voltage ranges needed. Vin: This input signal will be AC-coupled and multiplied by an inverting gain, -Rf/Rg. Cc: This capacitor provides DC blocking of the input signal. It is selected to have an impedance less than 1% of Rg at the minimum operating frequency Fmin. Cf: This capacitor rolls off the circuit bandwidth, to limit amplification of high-frequency noise. Rf & Rg: The ratio of Rf to Rg sets the gain, Vout/Vin = -Rf/Rg. If Rf or Rg is limited by the op amp's requirements, then the other resistor will be adjusted accordingly. Vref, Rb1, Rb2, Vbias: Vref is divided down by Rb1 & Rb2 to provide a bias voltage, Vbias. Vbias is applied to the noninverting input to bring its voltage within the op amp's normal operating range.
The AC-Coupled Inverting Amplifier multiplies the non-DC input voltage by the desired negative gain: 
    Vout = [-(Rf/Rg) x Vin(p-p)] + Vbias

Vbias is added to the op amp noninverting input to bring that input pin voltage within the normal operating range of the amplifier. It also provides an offset for the output, so that it is within its operating range.

The AC-Coupled Inverting Amplifier can also be used as a wide-bandwidth Bandpass Filter. Below the Minimum Signal Frequency, the signal will be attenuated at 20dB decade; above the Maximum Signal Frequency the attenuation will also be 20dB/decade. The attenuation at Maximum and Minimum Signal Frequency is approximately 1dB. For a narrow bandwidth Bandpass Filter, see the WEBENCH Active Filter Designer Custom Filters.

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