el8302 Intersil Corporation, el8302 Datasheet - Page 11

• Manufacturer Part Number: el8302
• Description: 500mhz Rail-to-rail Amplifier
• Manufacturer: Intersil Corporation

avoided because of their additional series inductance. Use
of sockets should also be avoided if possible. Sockets add
parasitic inductance and capacitance that can result in
compromised performance. Minimizing parasitic capacitance
at the amplifier’s inverting input pin is very important. The
feedback resistor should be placed very close to the
inverting input pin. Strip line design techniques are
recommended for the signal traces.
Typical Applications
VIDEO SYNC PULSE REMOVER
Many CMOS analog to digital converters have a parasitic
latch up problem when subjected to negative input voltage
levels. Since the sync tip contains no useful video
information and it is a negative going pulse, we can chop it
off. Figure 31 shows a gain of 2 connections for EL8302.
Figure 32 shows the complete input video signal applied at
the input, as well as the output signal with the negative going
sync pulse removed.
MULTIPLEXER
Besides the normal power down usage, the ENABLE pin of
the EL8302 can be used for multiplexing applications. Figure
33 shows two channels with the outputs tied together, driving
a back terminated 75Ω video load. A 2V
is applied to Amp A and a 1V
to Amp B. Figure 34 shows the ENABLE signal and the
resulting output waveform at V
before-make operation of the multiplexing. Amp A is on and
V
IN
75Ω
FIGURE 31. SYNC PULSE REMOVER
1K
FIGURE 32. VIDEO SIGNAL
V
OUT
V
+
-
1K
5V
IN
M = 10µs/DIV
V
V
S+
S-
11
P-P
OUT
75Ω
2MHz sine wave is applied
. Observe the break-
P-P
2MHz sine wave
75Ω
1V
0.5V
0V
1V
0.5V
0V
V
OUT
EL8302
V
signal is low and turns off in about 25ns when the ENABLE
signal is high. About 200ns later, Amp B turns on and V
passed through to the output. The break-before-make
operation ensures that more than one amplifier isn’t trying to
drive the bus at the same time.
SINGLE SUPPLY VIDEO LINE DRIVER
The EL8302 is wideband rail-to-rail output op amplifiers with
large output current, excellent dG, dP, and low distortion that
allow them to drive video signals in low supply applications.
Figure 35 is the single supply non-inverting video line driver
configuration and Figure 36 is the inverting video ling driver
configuration. The signal is AC coupled by C
are used to level shift the input and output to provide the
largest output swing. R
the virtual ground potential. R
resistors for the line. C
to minimize the droop of the luminance signal.
B
A
IN1
1V
2V
2MHz
2MHz
P-P
P-P
is passed through to the output when the ENABLE
ENABLE
75Ω
75Ω
FIGURE 33. TWO TO ONE MULTIPLEXER
1K
1K
A
ENABLE
1
F
+
-
+
-
, C
and R
FIGURE 34.
+2.5V
-2.5V
1K
+2.5V
-2.5V
1K
2
M = 50ns/DIV
and C
T
G
and R
set the AC gain. C
3
are selected big enough
3
are the termination
75Ω
B
1
. R
-0.5V
-1.5V
-2.5V
-1V
0V
1V
0V
1
and R
2
isolates
IN2
2
V
75Ω
OUT
is