Gain and Bandwidth of Op-Amps

• Gain: the ratio of output/input voltage.

  • Open loop.
  • Closed loop.

• Bandwidth: the range of frequencies where a particular gain can be maintained. Also denoted in Hz.

• Cutoff frequency: the maximum frequency we can achieve while maintaining a certain gain.

• The gain-bandwidth product is a constant parameter of each op-amp. It is useful in calculating the available bandwidth given the required gain or vice versa.

$$\text{Gain Bandwidth Product}=A_{CL}\times F_{\text{cutoff}}$$

• Given the open loop gain of a device, we can figure out what closed loop gain to extract out of it so that it has sufficient bandwidth for our use.
• If we set our closed loop gain to 1, the cutoff frequency will be same as the gain-bandwidth product. Cuz 1.