Hi All,
So I'm still having a go at this. Attached is a spreadsheet containing the transistor capacitance from the EPC2045. I've done some calculations and have some plots to try to get the charge curves from capacitance curve and hence the miller ratio. I still cannot agree with the result of the book , shown in the first post
Here is the transistor capacitance curves, digitized from datasheet
Using Q = CV, the Cgd was then converted to Qgd, though the curve does not look right. Vgs1 was left constant since it is the charge required to reach the threshold voltage. There the two of them were then divided to get the miller ratio. What am I doing wrong? The grey curve is on the secondary axis (right)
This is what I'm trying to get to with the grey curve
if anyone could have a look at the spread sheet attached at what I've done and maybe can find my error?