Hardware Reference
In-Depth Information
Fig. 3.3 The two types of
cells considered by
Normand [
2
](a) type-one
cell based on Wilson current
mirror [
3
](b) type-two cell
based upon Pookaiyaudom-
Quartet [
4
]
a
b
V
V
z
I
I
z
V
V
z
Q
5
Q
6
I
I
z
Q
3
Q
4
Q
3
Q
4
Q
1
Q
2
Q
1
Q
2
I
y
I
x
I
y
I
x
V
y
V
x
V
y
V
x
2
4
3
5
2
4
3
5
¼
2
4
3
5
0
2
=β
0
i
y
v
x
i
z
v
y
i
x
v
z
1
r
e
=β
0
ð
3
:
2
Þ
β
1
0
0
β þ
1
Like the type-one cell, the type- two cell also nearly works as a current conveyor.
An important property of Normand
s translinear current conveyors of Fig.
3.4a, b
is that they allow a very wide range input of I
x
which is theoretically extendable
to
'
I. In fact, the circuits can operate in class A mode when the input current I
x
is kept within the range of
β
I or they can be operated in class AB mode where
input current range can go even beyond these limits. The input resistance looking
into X port has been found to be 130
ʩ
for the first configuration and equal to 5
ʩ
for
the second configuration, for the DC bias current I
ʩ
are connected to reduce the effect of the offset voltages in the emitters of Q
6
and Q
8
(see Fig.
3.4b
). The trimmer Tr1 cancels the offset current at Y input for Vin
¼
100
ʼ
A. Resistors of value 5
0
while Tr2 and Tr3 compensate the output offset current and reduces the even
harmonics in the output for sine wave signal and Tr4 compensates the input offset
voltage.
¼
3.2.3 An Alternative CCII Implementation
Other than the four translinear mixed translinear loop employed in both Fabre [
1
]
and Normand [
2
] implementations of the second generation current conveyor, there
is an alternative four-transistor mixed-translinear-loop which is also used in quite a
number of other CC implementations. While the mixed translinear cell employed in
Fabre implementation has Y-input terminal on the junction of emitters of two
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