CMOS Optical Preamplifier Design Using Graphical Circuit Analysis

i in
5.1 Analysis of the Low-Voltage Transimpedance Amplifier 110
feedback that is associated with the common-gate configuration of M 1, L2 , the
feedback loop that extends from the input terminal to the gate of through ,
and L3 , the feedback loop around M 3 through resistor R f . The presence of overlapping
feedback loops makes this structure difficult for analysis using conventional
feedback techniques.
i in
– ( + )
g m1
Z in
g s1
v in
( + ) 1 –
Y A
gm1 + gs1 – gm2 Y f
Y f
Y f
M 2
vA ( Y f + Y L)
1 –
– gm3 Figure 5.3 Signal-flow graph of optical preamplifier superimposed
on circuit schematic.
– ( +
gm1 + gs1 )
i scin
g m1
L 1
g s1
– 1
Y in
v in
i scA
( + ) 1 –
L 2
– gm2 Y A
Y f
Figure 5.4 Signal-flow graph of preamplifier highlighting the
existing feedback loops.
Y f
L3 – gm3 + Y f
i scout
v out
vA ( Y f + Y L)
1 –
v out
M 1