What\s the difference between GBW, Unity Gain Bandwidth, Gain Bandwidth Product, and the -3dB frequency?
For many op amps, the open-loop gain drops with frequency at a steady rate, -20dB/decade. At any point on this downward slope, the product of the gain and the frequency at that point is constant, and is known as the Gain Bandwidth Product or GBW. If the op amp has been stabilized to operate at unity gain, then the Unity Gain Bandwidth, or the frequency at which the open loop gain is unity (gain of one) is usually equal to the Gain Bandwidth Product. This is shown on the “Open Loop Gain and Phase” plots as the frequency where the gain crosses through 0dB. Some op amps do not have a steady GBW, especially those not stabilized to operate at unity gain. In these cases, the GBW will be different from (usually higher than) the Unity Gain Bandwidth. The -3dB frequency is a measurement of the bandwidth of a closed-loop application of the op amp. The -3dB frequency is the point where the overall closed-loop gain drops by 3dB. The frequency at which the closed-loop application gain is unity can
