Basic ConceptsBasic ElectronicsCircuit AnalysisElectrical DesignElectronicsFormulas - Equations

Operational Amplifier (OP-AMP) – Formulas and Equations

Operational Amplifier (OP-AMP) Formulas

Operational Amplifier (OP-AMP) - Formulas and Equations

Operational Amplifiers:

Inverting Amplifier:

Inverting Amplifier

The following terms are used in the formulas and equations for Operational Amplifies.

  • Rf = Feedback resistor
  • Rin = Input Resistor
  • Vin ­­­= Input voltage
  • Vout = Output voltage
  • Av = Voltage Gain

Voltage Gain:

The close loop gain of an inverting amplifier is given by;

gain of an inverting amplifier

Output Voltage:

The output voltage is out of phase with the input voltage that is why it is known as the inverting amplifier.

Summing Amplifier:

Summing Amplifier

Output Voltage:

The general output of this given circuit above is;

Summing Amplifier

Inverted Amplified Sum of Input Voltage:

if the input resistors are same, the output is a scaled inverted sum of input voltages,

If R1 = R= R3 = R= R

Inverted Amplified sum of input voltage

Summed Output:

When all the resistors in the above given circuit are same, the output is an inverted sum of input voltages.

If Rf = R1 = R= R3 = R= R;

Vout = – (V+ V2 + V3 +… + Vn)

Non-Inverting Amplifier:

Non-Inverting Amplifier

Terms used for Non-Inverting Amplifier formulas and equations.

  • Rf = Feedback resistor
  • R = Ground Resistor
  • Vin ­­­= Input voltage
  • Vout = Output voltage
  • Av = Voltage Gain

Gain Of Amplifier:

The total gain of non-inverting amplifier is;

Non-Inverting Amplifier

Output Voltage:

The output voltage of non-inverting amplifier is in-phase with its input voltage and it’s given by;

output voltage of non-inverting amplifier

Unity Gain Amplifier / Buffer / Voltage Follower:

If the feedback resistor in removed i.e. Rf = 0, the non-inverting amplifier will become voltage follower/buffer.

Unity gain amplifier

Differential Amplifier:

Differential Amplifier

Terms used for Differential Amplifier formulas.

  • Rf = Feedback resistor
  • R= Inverting Input Resistor
  • R= Non Inverting Input Resistor
  • Rg = Non Inverting ground Resistor
  • Va ­­­= Inverting Input voltage
  • Vb ­­­= Non Inverting Input voltage
  • Vout = Output voltage
  • Av = Voltage Gain

General Output:

the output voltage of the above given circuits is;

Differential Amplifier

Scaled Differential Output:

If the resistor Rf = Rg  & R= R, then the output will be scaled difference of the input voltage;

Scaled Differential Output

Unity Gain Difference:

If all the resistors used in the circuit are same i.e. Ra = R= R= R= R, the amplifier will provide output that is the difference of input voltages;

Vout = V– Va

Differentiator Amplifier

Differentiator Amplifier

This type of Operational Amplifier provides the output voltage which is directly proportional to the changes in the input voltage. The output voltage is given by;

Differentiator Amplifier

Triangular wave input => Rectangular wave output

Sine wave input => Cosine wave output

Integrator Amplifier

Integrator Amplifier

This amplifier provides an output voltage which is the integral of the input voltages.

Integrator Amplifier

Related Formulas and Equations Posts:

➡️ READ FULL ARTICLE 📖

Electrical Technology

All about Electrical and Electronic Engineering & Technology. Join us on WhatsApp at Electrical Technology Official Channel, to receive the latest content, articles, and updates. You can also like and follow our social media networks below, or subscribe with your email to receive premium engineering articles in your mailbox.

Leave a Reply

Your email address will not be published. Required fields are marked *

Back to top button

Kindly permit ads on our free website.

It appears that you are using an ad blocker. We rely on advertising to support our website, provide free information, and sustain our services. Kindly consider whitelisting our website to allow ads.