Hardware Reference
In-Depth Information
frequency ranges 0-70 MHz for output Y and 0-340 MHz for output Z. The
output impedances (R
0
//C
0
) were found to be 220 K
ʩ
//3.5 pF for port Y and
1.1 M
ʩ
//1.1 pF for port Z. R
0
could be increased by reducing the DC bias current I
0
.
3.3 Commercially Available IC CCs
In this section we describe various commercially available CCs as well as other
devices which are although not labelled or termed as CCs in their manufacturer
s
data sheets and catalogues but nevertheless, can be either directly used as CCs or
can be modified to realize CCs.
'
3.3.1 CCII01 from LTP Electronics
Figure
3.17
shows the simplified schematic of the LTP CCII01. The device was
made available packaged as 8-pin DIL containing two CCIIs. It may be seen that the
basic architecture is a voltage follower between ports Y and X with power supply
current sensing mechanism implemented by the two current mirrors in the DC
power supply rails in a typical operational mirrored amplifier formulation which
senses the current input at port X and makes an equal current made available at the
high output impedance terminal Z.
Each individual CCII has a high input impedance Y-terminal with input imped-
ance as 80 k
ʩ
at 1 kHz while X-terminal has low input impedance of the order
of 10
.
Two CCII01 devices could be combined to make a composite CC with enhanced
characteristics with X- port input resistance reduced to a value as low as less than
200 m
ʩ
ʩ
at 1 MHz. The Z-port output impedance is of the order of 1 M
ʩ
at 1 kHz.
+V
y
Y
A
X
A
Z
A
Y
B
X
B
z
Z
B
1
R
F
x
Composite CC
−V
Fig. 3.17 The schematic of CCII01 IC current conveyor from LTP electronics [
17
]
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