I am measuring BJT DC h parameters hie and hre, so I measured the common emitter input characteristic, Ib vs Vbe for various Vce.

For a given Vbe, Ib should drop with and increase in Vce due to the early effect, but I measure an increase in Ib with increasing Vbe. Does anyone know what mechanism might cause this? Might I have the wrong measurement setup?

 

Hello,

The wiki has an article on the early effect:
http://en.wikipedia.org/wiki/Early_effect

Bertus

PS Don't use your email-adresses as user name.

 

I am measuring BJT DC h parameters hie and hre, so I measured the common emitter input characteristic, Ib vs Vbe for various Vce.

For a given Vbe, Ib should drop with and increase in Vce due to the early effect, but I measure an increase in Ib with increasing Vbe. Does anyone know what mechanism might cause this? Might I have the wrong measurement setup?

You are saying different things at different points: You say it should drop with increasing "Vce" but that you observe that it increases with increasing "Vbe". Which of those, if either, is a typo?

I don't recall the Early Effect saying anything regarding the base current. I recall it addressing the increase in collector current as the collector-emitter voltage increases and, thus, the collector current increasing for the same base current.