Hardware Reference
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a
CCII
1
z+
x
D
1
CCII
2
I
0+
(t)
z+
x
z+
y
z−
I
in
(t)
D
2
I
0−
(t)
y
z−
V
B
b
CCII
1
z+
x
CCII
2
R
1
D
1
z+
x
z+
V
0+
(t)
y
R
3
z−
+
D
2
V
B
V
in
(t)
y
z−
V
0−
(t)
−
R
2
Fig. 15.5 Precision full-wave rectifiers [
5
](a) current-mode (b) voltage-mode
R
1
v
in
t
,
R
1
v
in
t
;
R
3
R
2
v
Oþ
t
ðÞ
¼
ðÞ
:
v
O
t
ðÞ
¼
ðÞ
ð
15
:
20
Þ
The experimental and simulation results have confirmed that although as compared
to the traditional op-amp based precision rectifiers, the CC-based precision recti-
fiers presented in [
5
] have somewhat larger DC error but on the other hand, they
have superior transient response. These circuits are obviously superior to their
op-amp based counterpart when the input signals to be rectified are in the vicinity
of 1 MHz or so.
15.5.2 Kumngern
'
s Full Wave Rectifier
Kumngern [
6
] demonstrated that a novel full wave rectifier can be made from only
two differential difference current conveyors (DDCC) without requiring any
diodes. His proportion is shown in Fig.
15.6
.
The operation of this circuit can be explained as follows. When V
in
is positive,
the DDCC1is ON, the voltage V
in
is followed by the DDCC1 and appears at the
X-terminal and hence, at the output of the circuit. On the other hand, when V
in
is
negative, this negative voltage is followed by DDCC2 and is conveyed to its X
terminal. The relation between input voltage V
in
and output voltage V
out
can be
expressed as:
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