ECE 3050 Analog Electronics - BJT Formula Summary · PDF fileECE 3050 Analog Electronics - BJT...

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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. V CE becomes V EC . When more than one equation is given, either can be used. i C = I S e v BE /V T I S = I S0 μ 1+ v CE V A i B = i C β i E = i C + i B β = β 0 μ 1+ v CE V A g m = I C V T r π = V T I B = (1 + β) r e r e = V T I E = r π 1+ β = α g m r 0 = V A + V CE I C α = β 1+ β β = α 1 α r e α = r π β r 0 e = R tb + r x + r π 1+ β = R tb + r x 1+ β + r e i 0 c = g m v b 0 e = αi 0 e = βi b i c(sc) = G mb v tb G me v te G mb = α r 0 e + R te kr 0 r 0 R te r 0 + R te G me = 1 R te + r 0 e kr 0 αr 0 + r 0 e r 0 + r 0 e r ic = r 0 + r 0 e kR te 1 αR te / (r 0 e + R te ) R tb =0,rx=0 = r 0 [1 + g m (r π kR te )] + R te v e(oc) = v tb r 0 + R tc / (1 + β ) r 0 e + r 0 + R tc / (1 + β ) r ie = r 0 e r 0 + R tc r 0 e + r 0 + R tc / (1 + β ) v b(oc) = v te r 0 + R tc R te + r 0 + R tc r ib = r x + (1 + β ) r e + R te (1 + β ) r 0 + R tc r 0 + R te + R tc = r x + r π + R te (1 + β) r 0 + R tc r 0 + R te + R tc r 0 large = r x + r π + (1 + β) R te r 0 Approximations — Assume r 0 = except when calculating r ic i 0 e = i e i c(sc) = i 0 c = αi e = βi b = G m (v tb v te ) G m = α r 0 e + R te r 0 e = R tb + r x + r π 1+ β = R tb + r x 1+ β + r e r ic = r 0 + r 0 e kR te 1 αR te / (r 0 e + R te ) v e(oc) = v tb r ie = r 0 e v b(oc) = v te r ib = r x + r π + (1 + β) R te = r x + (1 + β )(r e + R te ) 1

Transcript of ECE 3050 Analog Electronics - BJT Formula Summary · PDF fileECE 3050 Analog Electronics - BJT...

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 reversethe order of subscripts involving node labels, i.e. VCE becomes VEC . When more than one equation isgiven, either can be used.

iC = ISevBE/VT IS = IS0

µ1 +

vCEVA

¶iB =

iCβ

iE = iC + iB β = β0

µ1 +

vCEVA

¶gm =

ICVT

rπ =VTIB

= (1 + β) re re =VTIE

=rπ1 + β

gmr0 =

VA + VCEIC

α =β

1 + β

β =α

1− α

reα=

rπβ

r0e =Rtb + rx + rπ

1 + β=

Rtb + rx1 + β

+ re i0c = gmvb0e = αi0e = βib

ic(sc) = Gmbvtb −Gmevte Gmb =α

r0e +Rtekr0r0 −Rte/β

r0 +RteGme =

1

Rte + r0ekr0αr0 + r0er0 + r0e

ric =r0 + r0ekRte

1− αRte/ (r0e +Rte)

Rtb=0, rx=0= r0 [1 + gm (rπkRte)] +Rte ve(oc) = vtbr0 +Rtc/ (1 + β)

r0e + r0 +Rtc/ (1 + β)

rie = r0er0 +Rtc

r0e + r0 +Rtc/ (1 + β)vb(oc) = vte

r0 +Rtc

Rte + r0 +Rtc

rib = rx + (1 + β) re +Rte(1 + β) r0 +Rtc

r0 +Rte +Rtc= rx + rπ +Rte

(1 + β) r0 +Rtc

r0 +Rte +Rtc

r0 large= rx + rπ + (1 + β)Rte

r0 Approximations — Assume r0 =∞ except when calculating ric

i0e = ie ic(sc) = i0c = αie = βib = Gm (vtb − vte) Gm =α

r0e +Rte

r0e =Rtb + rx + rπ

1 + β=

Rtb + rx1 + β

+ re ric =r0 + r0ekRte

1− αRte/ (r0e +Rte)ve(oc) = vtb

rie = r0e vb(oc) = vte rib = rx + rπ + (1 + β)Rte = rx + (1 + β) (re +Rte)

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