Whats wrong with this circuit...?

Thread Starter

Himanshoo

Joined Apr 3, 2015
265
@jony 130

In your video mentioned in post #10...the author says that
if the value of capacitor would be high then droop would improve but it will take time to charge the capacitor due to limited slew rate of the opamp and hence efficient tracking of input voltage won’t be possible..
But the rate of charge of capacitor also depends upon the size of the capacitor(i.e capacitance).....so in this circuit which has a major effect on charging the capacitor ...is it the slew rate or the capacitance of the capacitor..
Does the entire charging of the capacitor depends on slew rate..or the capacitance...?
Which of the two has the dominant effect....?
 
Last edited:

crutschow

Joined Mar 14, 2008
38,515
In your video mentioned in post #10...the author says that
if the value of capacitor would be high then droop would improve but it will take time to charge the capacitor due to limited slew rate of the opamp and hence efficient tracking of input voltage won’t be possible..
But the rate of charge of capacitor also depends upon the size of the capacitor(i.e capacitance).....so in this circuit which has a major effect on charging the capacitor ...is it the slew rate or the capacitance of the capacitor..
Does the entire charging of the capacitor depends on slew rate..or the capacitance...?
Which of the two has the dominant effect....?
It can be either.
The charging rate of the capacitor is determined by the size of the capacitor and the maximum output current the op amp can deliver.
Thus for a given op amp output current you want to make the capacitor as small as possible to achieve fast tracking while still keeping the droop to an acceptable value. It's a trade-off between acquisition time and droop.
 
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