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a
+V
M
1
M
3
y
x
z
M
4
M
2
−V
+V
+V
M
9
M
5
M
6
M
10
M
7
M
8
−V
−V
Fig. 4.4 Class AB first generation current conveyors proposed by Bruun (a) without bias
stabilization (b) with bias stabilization [
10
]
I
QY
¼
I
D1
¼
I
Qx
¼
I
D3
¼
I
SS
=
ð
1
λ
FB
Þ
ð
4
:
1
Þ
If (1-
ʻ
FB
) is reasonably large as compared to expected mismatch in the devices, a
well-controlled quiescent current mechanism is, thus, available. Now, in order that
as required for a CCI, i
y
can be made equal to i
x
, a fraction (1-
ʻ
FB
) of the X- branch
current must be feedback directly to the Y-input. This function is performed by the
MOSFETs M
5b
and M
7b
.
Subject to the assumption of matched transistors having same g
m
and neglecting
the bulk effect, the input resistance looking into the port-X is given by:
1
2
gm
1
R
x
¼
ð
λ
FB
Þ
ð
4
:
2
Þ
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