mona123
Member level 5
gm of BJT is 40*Ic. So does it mean gm is independent of device size and shape? So I can get same gm with smaller device and larger device for same amount of current applied? Then why would one use large devices? Thanks.
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gm of BJT is 40*Ic. So does it mean gm is independent of device size and shape? So I can get same gm with smaller device and larger device for same amount of current applied? Then why would one use large devices? Thanks.
No it's a basic quantity in many design calculations. But other real word parameters need to considered additionally. You can find out yourself by reviewing design excercise problems in text books.So is gm a useless quantity in BJT then?
I don't know about your text books. Mine are using gm in many places, e.g. Analysis and Design of Analog Integrated Circuits by Gray/Hurst/Lewis/Meyer. The role of the parameter gm corresponds to the description of the transistor as voltage controlled current source in basic transistor models. gm isn't but the derivative of Ic = f(Vbe).If it was clear in text book, i wouldn't have asked here If you know a particular section of a textbook that describes the importance of gm in BJT, that will be helpful. Thanks.
Trans conductance is not directly used in a BJT but in other forms in h parameter model design
the model you
who is "you"?
are talking about is Z model and the one I meant was H representation of Tranny that is all the difference that is the reason why some of the books he referred are not having the ame in question
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and do you mean hoe as trans conductance
Yes Gm is the inverse of resistance
R = V/I
Gm = I/V, which is why i said it determines how well voltage can be transferred into current, i was not wrong in what i said
I see several inaccuracies involved with the expression.R = V/I
Gm = I/V, which is why i said it determines how well voltage can be transferred into current, i was not wrong in what i said
Ic = f(Vbe)
gm = dIc/dVbe
ro = dVce/dIc