Great Expectations Come From Basic Understandings

Blog Post created by analogkidr on Aug 21, 2012

Gain-bandwidth product GBWP, a fixed quantity for any voltage-feedback amplifier (this is not true for current-feedback amplifiers), can be determined from the open-loop gain plot found in a datasheet. Simply pick a point on the linear portion of the open-loop gain response after the –3 dB point, multiply the gain (in V/V, not dB) by the corresponding frequency, and you have the GBWP. You can also use the unity-gain crossover as the GBWP if there are no parasitic poles, but high-speed amplifiers tend to have parasitic poles close to the unity-gain crossover, so we tend to stay away from those when calculating the GBWP. Once the GBWP is calculated, the bandwidth for a given gain or the gain for a given frequency can be determined.


Learn more about GBWP in Great Expectations, as published in the September 2012 issue of Analog Dialogue.

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