Hardware Reference
In-Depth Information
a
b
CCII±
CCII±
R 1
y
y
V in
V in
z
z
V 0
V 0
x
x
C 1
C 1
R 1
Fig. 5.7 CC-based integrators (a) Non-inverting/Inverting integrator from CCII
(b) Inverting/
Non-inverting integrator from CCII
5.2.4
Integrators and Differentiators
Integrators and differentiators are important building blocks with numerous appli-
cations in the design of waveform shaping circuits, filters, oscillators etc. and their
realizations using CCs have been dealt with by several authors, for instance, see
[ 75 , 154 - 159 ].
The realization of non-inverting integrator is attained by connecting a resistor at
port-X and terminating port-Z into a capacitor connected to ground (see Fig. 5.7a ).
The transfer function of both the circuits can be expressed as:
V 0
V in ¼
1
sC 1 R 1
ð
5
:
12
Þ
where the + sign is applicable for CCII+ and negative sign corresponds to CCII
.
Alternatively, a CCII+ can also be used to realize an inverting integrator by the
circuit configuration shown in Fig. 5.7b .
A differential input integrator can be realized with the circuit arrangement
shown in Fig. 5.8 which also uses only two CCIIs+ and a voltage follower but
can be realized using only two AD844. The circuit is characterized by the following
equation:
1
sC 1 R 1 V 1
V 0 ¼
ð
V 2
Þ
ð
5
:
13
Þ
In principle, from all the three circuits described above, the corresponding
differentiator circuits can be obtained by replacing the resistor by a capacitor and
vice-versa.
In current mode filter design, current mode oscillators and other current mode
signal processing applications, there may be the requirement of a current mode
integrator/differentiator. Three configurations to realize such integrators are shown
in Fig. 5.9a-c .
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