how to measure the output resistance of LDO?

[renwl]

Normally,we need very low output resistance of LDO. I want to know how to measure the output resistance of LDO.

thanks

 

[neoflash]

one easy way is that after biasing your LDO, put a AC current source at the output of LDO, measure the AC voltage you get.

Make sure your loop is closed if you want to get closed-loop Ro. Or you just break the loop and get open-loop impedance.

 

[renwl]

when we test the LDO,is this method still useful?

 

[neoflash]

why not?