Electronic – Increasing in slope result in increasing in impedance of BJT Early voltage

bjt

I'm studying about the AC equivalent model of BJT and in the re model, it said that:

"As the base current increases the slope of the line increases, resulting in an increase in output impedance with increase in base and collector current"

Characteristic curve

I thought that the impedance is equal to the ro in the denominator, so base on the formula of the slope in the picture then if the slope increases, the value of ro decreases and therefore the impedance should decrease rather than increase.

Am I missing something?

Best Answer

"As the base current increases the slope of the line increases, resulting in an increase in output impedance with increase in base and collector current"

They got it wrong - as the slope increases you get more amps per volt so conductance increases and conductance is the inverse of resistance.

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