Op-Amp Gain & Bandwidth Calculator

Operational Amplifiers (Op-Amps) are analog building blocks used to scale, filter, or compare signals.

Formulas:

• Non-Inverting Gain: Av = 1 + (Rf / Rg)
• Inverting Gain: Av = - (Rf / Rg)
• Schmitt Trigger (Non-Inv) Hysteresis: Thresholds at Vth = (Vref * R1 +/- Vsat * R2) / (R1 + R2)

Usage: Select your configuration and input resistor values to calculate gain, output voltage, or Schmitt trigger hysteresis thresholds.

When you need it: Setting an inverting or non-inverting stage's gain and checking the resulting bandwidth against the op-amp's gain-bandwidth product, so your signal isn't quietly rolled off.

Worked example: A non-inverting gain of 11 (Rf = 10 kΩ, Rg = 1 kΩ) built on a 1 MHz GBW op-amp gives a bandwidth of GBW / gain = 1e6 / 11 ≈ 91 kHz. More gain buys less bandwidth.

Tips & gotchas:

• Gain × bandwidth is roughly constant (the GBW product) — trade one directly for the other.
• Slew rate limits large, fast signals independently of GBW; check both for a step or high-amplitude sine.
• Input bias current flowing through the source resistance shows up as an output offset — balance the input resistances.
• Driving a capacitive load can cause ringing; a small series resistor or feedback cap restores stability.