http://www.allaboutcircuits.com/vol_3/chpt_8/9.html
Stated: "Another limitation of this amplifier design is the fact that its input impedances are rather low...Each input voltage source has to drive current through a resistance, which constitutes far less impedance than the bare input of an op-amp alone. The solution to this problem, fortunately, is quite simple. All we need to do is "buffer" each input voltage signal through a voltage follower"
Why does the addition of a resistor lessen the impedance? Shouldn't it be the other way around?
Thanks for your help!
Stated: "Another limitation of this amplifier design is the fact that its input impedances are rather low...Each input voltage source has to drive current through a resistance, which constitutes far less impedance than the bare input of an op-amp alone. The solution to this problem, fortunately, is quite simple. All we need to do is "buffer" each input voltage signal through a voltage follower"
Why does the addition of a resistor lessen the impedance? Shouldn't it be the other way around?
Thanks for your help!