Gain-Bandwidth Product

In multiple stage amplifiers, as the number of stages is increased to increase gain, the bandwidth decreases to some extent generally, but not according to the gain-bandwidth-product relation. 

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An additional consideration is the gain-bandwidth product specification of the operational amplifier used as the error amplifier. If the Bode character-... 

Another limiting factor is the bandwidth of the op-amp. On the factory specifications, the commonly used indicator is the gain-bandwidth product. The nominal dc gain is valid up to a cutoff frequency / which is typically 10 Hz. Above that frequency, the gain g is inversely proportional to the frequency. The product of gain and frequency, the gain-bandwidth product/a is typically 1 MHz. The input impedance of the amplifier increases with frequency ... 

The gain-bandwidth product GB of the op-amp is GB = Aoco, and the op-amp time constant is denoted as r = 1 /GB. For analyses in which the frequencies of interest are much greater than , A(s) is usually approximated as... 

The quantity ct)cL f is the closed-loop gain-bandwidth product, and so Eq. (7.111) shows that the closed-loop gain-bandwidth product for this ampHfier equals the open-loop gain-bandwidth product. 

The output current is also Hmited. The output current for a /uA741 op-amp is limited to about 25 mA by internal protection circuitry. Thus, the current demanded from the output of this op-amp should be kept below 25 mA to avoid distortion of the output waveform. In fact, the output current demand should be kept small for best results because most parameters of an op-amp, such as gain-bandwidth product, degrade as output current demand is increased. 

Gain-bandwidth product (GB) The product of the magnitude of op-amp gain at DC and its open loop bandwidth. 

Op-amp time constant (r) The reciprocal of the gain-bandwidth product of the op-amp. 

Aronhime, RB. 1977. Effects of finite gain-bandwidth product on three recently proposed quadratic networks. IEEE Trans, on Circuits and Systems CAS-24(Nov.) 657-660. 

The gain-bandwidth product theorem states simply that in a single-stage amplifier, as gain is increased, bandwidth decreases such that the area under the frequency-response curve (Figure 7.9) remains constant. Simply the... 

Feedback circuits - so that they do not become unstable due to temperature variations affecting component parameters (e g. gain-bandwidth product, phase margin, etc.). 

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