Current Sources and Voltage References

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Op amp supply bypassing and input protection

impressive. For precision current source applications, having an op amp

with either a high PSRR of more than 90 dB or a low PSRR of less than

20 µV/V will be helpful in one’s design, because this will buffer changes

in the supply rails and the load voltage, from the constant current output

to the load.



Gain bandwidth product (G

BW

or f

T

).

This specification refers to the fre-

quency range from DC to the frequency at which the open-loop gain

equals unity. Each op amp is designed so that its gain reduces as the fre-

quency rises, and this falls off at a rate of about 6 dB/octave. Normally,

the op amp would ...