Gain-Bandwidth Product

Formula

Description

The gain-bandwidth product is a constant for a given op-amp, meaning that as closed-loop gain increases, the usable bandwidth decreases proportionally. An op-amp with a GBW of 10 MHz can provide a gain of 10 up to 1 MHz, a gain of 100 up to 100 kHz, or unity gain up to 10 MHz. This fundamental tradeoff arises from the dominant-pole compensation used to ensure stability in feedback configurations. Selecting an op-amp with sufficient GBW for the required gain at the signal frequency is a critical design step.

Variables

• GBW — Gain-bandwidth product (Hz)
• Gain — Closed-loop voltage gain (V/V, dimensionless)
• f — Maximum usable frequency at that gain (Hz)

Practical Notes

GBW applies to voltage-feedback op-amps with a single dominant pole. Current-feedback op-amps do not follow this rule and can maintain high gain at high frequencies. Common GBW values: LM358 1 MHz, TL072 3 MHz, OPA2134 8 MHz, AD8065 145 MHz. For stability, ensure the loop gain crosses 0 dB at a rate of 20 dB/decade.