Hardware Reference
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+V
+V
+V
+V
µA749C
Y
X
i
X
Q
1
+
−
Q
2
Q
3
Q
4
I
B
+ i
x
I
B
I
B
+ i
x
R
B
I
B
−V
Z
i
X
Q
5
Q
6
I
B
+ i
x
I
B
Q
7
Q
8
−V
Fig. 2.2 Simplified form of integrable CCII
proposed by Black et al. [
1
]
now easy to see that the collector current of Q
1
which is I
B
+i
x
is duplicated in Q
2
where from, through NPN current mirror Q
7
-Q
8
it is replicated in collector of Q
8
.
Since the junction of the collectors Q
4
and Q
8
constitute the Z- port, from the
various current components shown in the diagram it follows that current going into
Z- terminal will be same as current coming out of X- terminal and therefore the
circuit realizes a CCII
.
made this way exhibited a voltage gain between ports Y and X of the
order of 0.9997, an input impedance looking into port Y as 130 M
ʩ
, output
resistance looking into terminal X as 0.45
ʩ
and an offset of the order of 0.5 mV
between ports Y and X. The output impedance looking into terminal Z could be
raised by using Wilson current mirrors at the output end which was found to be of
the order of 80 M
The CCII
when the simple mirrors at the Z-output were replaced by an
elaborate controlled positive feedback based mirror arrangement.
ʩ
2.2.2 Bakhtiar-Aronhime
'
s Entirely Op-Amp-Based
Implementation
In reference [
2
], Bakhtiar and Aronhime demonstrated for the first time how a CCII
(both + and
) can be realized exclusively using only op-amps and resistors. Their
proposition is shown in Fig.
2.3
. In this circuit, the first op-amp along with a resistor
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