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CMOS Optical Preamplifier Design Using Graphical Circuit Analysis

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v s<br />

i ti<br />

that part of the SFG for Q 2 can be eliminated because of its common-emitter config-<br />

uration. The final SFG including all the branch and node expressions is shown in<br />

Figure A.3. The various branch transmittances are calculated below:<br />

v s<br />

[a]<br />

G s<br />

a<br />

a = 0.001S b = 500Ω c = – 0.1S<br />

d = 909.09Ω e = – 0.1S f = 333.33Ω<br />

g = 0.002S h = 0.101S i = 7.209Ω<br />

j = 0.001S k = 0.1S l = 0.002S<br />

b<br />

[b]<br />

R || s β ⁄ gm1 i sc1<br />

j<br />

c<br />

h<br />

k<br />

d<br />

i<br />

0<br />

ve2= 0<br />

Figure A.2 SFG for wideband feedback amplifier.<br />

[c]<br />

–<br />

v 1<br />

[j]<br />

gm1 ⁄ β<br />

g m1<br />

i sc2<br />

Figure A.3 Simplified SFG for wideband feedback amplifier.<br />

v 3<br />

v 2<br />

i to<br />

e<br />

[d]<br />

[e]<br />

R ||<br />

1 β ⁄ gm2 – gm2 [k]<br />

g m1<br />

[h]<br />

gm1 ⁄ α<br />

l<br />

i sco<br />

[l]<br />

G f<br />

[i]<br />

R ||<br />

α<br />

e R || f --------<br />

g m1<br />

f<br />

g<br />

[f]<br />

R ||<br />

2 R f<br />

i sc3<br />

[g]<br />

G f<br />

169<br />

v out<br />

v o

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