Summary - Bjt formula PDF

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BJT Formula...

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ECE 3050 Analog Electronics - BJT Formula Summary Equations are for the npn BJT. For the pnp device, reverse the directions of all current labels and reverse the order of subscripts involving node labels, i.e.

VCE

becomes

VEC .

When more than one equation is

given, either can be used.

µ

¶

µ

¶

iC vCE iB = iE = iC + iB β = β0 1 + iC = IS e IS = IS0 β VA α β rπ VA + VCE VT VT IC = α= = r0 = = (1 + β ) re re = rπ = gm = 1+β 1+β IC IE gm IB VT re α R + r + r rπ R + r tb x π tb x β= r 0e = + re ic0 = gm vb0 e = αi0e = βib = = 1−α α 1+β β 1+β r0 − Rte/β α 1 αr0 + re0 ic(sc) = Gmbvtb − Gme vte Gmb = 0 Gme = re + Rtekr0 r0 + Rte Rte + re0 kr0 r0 + re0 0 r0 + Rtc/ (1 + β ) r0 + re kRte Rtb =0, rx =0 ric = = r0 [1 + gm (rπ kRte)] + Rte ve(oc) = vtb 0 1 − αRte / (r 0e + Rte ) re + r0 + Rtc/ (1 + β ) r0 + Rtc r0 + Rtc vb(oc) = vte rie = re0 0 Rte + r0 + Rtc re + r0 + Rtc/ (1 + β ) (1 + β ) r0 + Rtc (1 + β ) r0 + Rtc r0 large rib = rx + (1 + β ) re + Rte = rx + rπ + Rte = rx + rπ + (1 + β ) Rte r0 + Rte + Rtc r0 + Rte + Rtc vCE 1+ VA

vBE /VT

r0

Approximations — Assume

i0e

= ie

ic(sc)

r0

= 0

∞

= ic =

except when calculating

αie

=

βib

=

Gm (vtb − vte)

ric Gm

=

α re0 + Rte

r0 + re0 kRte Rtb + rx + rπ Rtb + rx ve(oc) = vtb + re ric = = 1+β 1+β 1 − αRte / (r 0e + Rte ) vb(oc) = vte rib = rx + rπ + (1 + β ) Rte = rx + (1 + β ) (re + Rte) rie = re0

re0

=

1...