
http://www.national.com
10
Special Evaluation Board
Considerations for the CLC5612
To optimize off-isolation of the CLC5612, cut the R
f
trace
on both the CLC730038 and the CLC730036 evaluation
boards. This cut minimizes capacitive feedthrough
between the input and the output. Figure 13 shows where
to cut both evaluation boards for improved off-isolation.
Figure 13: Evaluation Board Changes
SPICE Models
SPICE models provide a means to evaluate amplifier
designs.
Free SPICE models are available for
Comlinear’s monolithic amplifiers that:
I
Support Berkeley SPICE 2G and its many derivatives
I
Reproduce typical DC, AC, Transient, and Noise
performance
I
Support room temperature simulations
The
readme
file that accompanies the diskette lists
released models, and provides a list of modeled parame-
ters.
The application note OA-18, Simulation SPICE
Models for Comlinear’s Op Amps, contains schematics
and a reproduction of the readme file.
Single Supply Cable Driver
Figure 14 below shows the CLC5612 driving 10m of 75
coaxial cable. The CLC5612 is set for a gain of +2V/V
to compensate for the divide-by-two voltage drop at
V
o
.
The response after 10m of cable is illustrated in
Figure 15.
Figure 14: Single Supply Cable Driver
Figure 15: Response After 10m of Cable
Differential Line Driver With Load
Impedance Conversion
The circuit shown in the
Typical Application
schematic
on the front page and in Figure 16, operates as a
differential line driver. The transformer converts the load
impedance to a value that best matches the CLC5612’s
output capabilities. The single-ended input signal is
converted to a differential signal by the CLC5612. The
line’s characteristic impedance is matched at both the
input and the output. The schematic shows Unshielded
Twisted Pair for the transmission line; other types of lines
can also be driven.
Application Circuits
1
7
6
8
5
3
4
2
1k
+
-
+
-
1k
1k
1k
0.1
μ
F
6.8
μ
F
+
V
in
5k
5k
0.1
μ
F
+5V
+5V
0.1
μ
F
V
o
10m of 75
Coaxial Cable
75
0.1
μ
F
75
CLC5612
NOTE:
Channel 2 not shown
1
20ns/div
V
in
= 10MHz, 0.5V
pp
Cut traces here
730036 Bottom
CLC730038
REV C
OUT2
GND
IN2
IN1
OUT1
+Vcc
-Vcc
ROUT2
RG2
RF2
C3
+
C4
+
C1
C2
ROUT1
RF1
RG1RIN1
RIN2
(970) 226-0500
Cut traces here
730036 Top