High input impedance.

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Maintenance Man

Joined May 12, 2010
25
We are studying amplifiers in electronics class, and I am having trouble understanding why a good amplifier has high impedance at the input. Is it to cause low current flow at the input while keeping the voltage at a constant? If someone could give me an easy explanation, I would greatly appreciate it. Thank you very much. :confused:
 
It is to prevent "loading effect" from previous stages. Otherwise, if the input impedance is smaller, you will get sort of a voltage divider effect. You will lose gain.
 
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