Impedance requirements

[Akshe]

Hi,

Can someone pls help me understand how do we decide whether we require a high or low impedance (both wrt input and output impedance) for a circuit?
Is this logic correct - if the input current is to be minimum my input impedance should be low and if i want to deliver the maximum output current then my output imp should be high? Then how does it vary from circuit to circuit eg. voltage reference generators,amplifiers etc.
Any good links to help me understand this would also be helpful.

 

[emresel]

Hi;
It depends on your input source and load imp.
ie you have a weak source (it can drive small ampunts of currents), then you need to design a cct (ie buffer or amplifier) that source should sink small amount of current so that don't disturb the weak source.
On the other ahnd ie you want to drive 1kohm load, in this case your source device (this is the output imp of your cct) should be small, so that you can deliver the power to the load. Consider what if your cct output is also around 1kOhm, then you can deliver only the half of power. This is called loading effect.
This may also help:https://answers.yahoo.com/question/index?qid=20100128134432AALqX2r

 

[Akshe]

Thanks a lot for the explanation..