Voltage follower

Tags

• amplificadores
• Amplifiers and op-amps
• Electronics
• physics
• Electronics formula
• physics formula
• Op-amp

Detail

Explore the idea

Variables

• $v_+,v_-,v_o,v_{\mathrm{in}}$V
• $A$gain (dimensionless)
• $R_f,R_{\mathrm{in}},R_g$Ω
• $\mathrm{CMRR}$dimensionless.

Conditions

• Ideal op-amp with negative feedback except comparator; |Vo| < Vsat.

Intuitive explanation

For “Voltage follower”: with negative feedback v+ ≈ v− (virtual node) and the resistor network sets the gain.

Worked example

Common mistakes

• forgetting the virtual node
• using inverting gain on a non-inverter
• ignoring |Vo| < Vsat

Frequently asked questions

What must be checked before using the Voltage follower relation?

Confirm negative feedback, the virtual node and that Vo does not saturate.

Also known as

• inverting amplifier, non-inverting, virtual node, CMRR, comparator

Related topics

• Basic op-amp

Conventions

• V or dimensionless

Related formulas

• Related

  Non-inverting amplifier

  $$v_o=\left(1+\frac{R_f}{R_g}\right)v_{\mathrm{in}}$$
  Open formulaOpen in section

• Related

  Inverting summer

  $$v_o=-R_f\sum_k\frac{v_k}{R_k}$$
  Open formulaOpen in section

• Related

  Voltage divider

  $$V_o=V_i\frac{R_2}{R_1+R_2}$$
  Open formulaOpen in section

• Related

  Superposition principle

  $$x=\sum_k x_k$$
  Open formulaOpen in section