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What is Gain bandwidth product (GBW OR GB?)

   Refer to the multiple of the open loop gain (continuous for a given amplifier).

Gain bandwidth product is commonly uses in the operational amplifier to let circuit designers to determine the highest gain that can be extorted from the apparatus for a given frequency (or bandwidth at any constant point)

            Importance of the Gain Bandwidth

A little gain bandwidth is desirable for constant single-frequency operation

It can limit the range for wavelength tuning

           Open-loop Frequency Response Curve

(Electronics Tutorial about Operational Amplifiers)

   The open-loop frequency response curve shown above we can observe that the product of the gain against frequency is steady at any point along the curve and in addition to that we can see the unity gains (0dB) frequency also determine the gain of the amplifier at any position along the curve. This constant is usually known as the Gain Bandwidth Product(GBP, GB).

Hence, GBP = Gain x Bandwidth or A * BW.

For example, from the graph above the gain of the amplifier at 100 kHz = 20dB or 10, then the

GBP = 100,000Hz * 10 = 1,000,000. Or 100,000Hz * 20 = 2,000,000

Likewise, a gain at 1 kHz = 60dB or 1000, so the

GBP = 1,000 * 1,000 = 1,000,000. Identical!

The Voltage Gain (A) of the amplifier can be set up using the following formula:

Voltage Gain, (A) = V Out/Vin

And in Decibels or (dB) is known as:

20log (A) or 20logV out/Vin in dB