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SR stands for "slew rate" and it is a ratio between change of otput voltage and its rising time when the input signal is a pulse (square). Example: If slew rate = 0.25V/µs then at Uout of 10V the maxium frequency will be 4kHz
BW and 3dB: Bandwidth can be described as frequency range from 0Hz (Fmin) to Fmax at which the gain decreases by 3dB comparing to gain at 0Hz (Fmin)
slewing originates from charging a capacitor at the output node with a constant current to improve it increase output current
in other words decrease gain of the amplifier
take care it is a large signal behavior
Added after 4 minutes:
3 dbw is the product of the highest gain ( mid band) & the frequency at which this gain is halfed
care it is a small signal response ( ac sweep)
If you use operational amplifier work in voltage follower. You maybe can consider high speed operational amplifier. For instance,the LM6172 of National Semiconductor. Its Slew Rate is 3000V/us.
And the 3dB Bandwidth is mean that you can useful frequency range.
Basically SR is defined as how fast the output voltage can response to the given input signal in the short time. The factors which normally degrade the SR are the output load and miller compensation capacitors. It is defined that SR=Ic/C, so as others mentioned, you can improve your opamp slew rate by increasing the dc biasing current of your last stage opamp or decrease the miller compensation capacitor or both.
3db bandwidth of any amplifier will be the frequency at which the gain will reduce by 3db from it'd dc gain. As others said, SR can be improved by increasing the output current.
slew rate is a large signal phenomena that deals with how quickly the output changes when there is a large change in the input, i.e. a step response. In order to increase SR, increase current.
If u are working with differential topologies, take care about a symmetrical slewing of the output stage because sometimes one of the branches is faster than the other one.
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