el2008 Intersil Corporation, el2008 Datasheet - Page 7

• Manufacturer Part Number: el2008
• Description: 55mhz 1 Amp Buffer Amplifier
• Manufacturer: Intersil Corporation

Unfortunately the isolation resistor is not inside the op amp
feedback loop and cannot be neglected when computing the
DC voltage gain into a resistive load. If load dependent DC
gain is not tolerable then additional high frequency feedback
from the op amp output (the EL2008 input) and an isolation
resistor from the buffer output can be used to stabilize the
loop. This configuration requires the op amp to be unity gain
stable. This feedback method will allow the EL2008 to boost
the output of the EHA2505 amplifier below and serve as a
variable, bipolar 1A voltage supply with short circuit
protection.
1000pF
3300pF
470pF
0.1µF
13pF
1µF
5µF
C
L
Slew Rate = 1A/C
7
350ns
45ns
50ns
55ns
60ns
20µs
4µs
t
R
L
O.S.
20%
20%
30%
30%
0%
0%
0%
EL2008
Video Distribution Amplifier
The EL2008 can drive 15 double matched 75: cables. If the
EL2008 is used within an op amp feedback loop the output
levels are independent of loading. The circuit below accepts
1 of 2 inputs and drives 15 cables. Pin 8 of the EL2020
(Disable) is used to multiplex between the inputs and can be
easily expanded to accept more inputs. The circuit as shown
when fully loaded has differential phase < 0.1° and
differential gain < 0.1%. The 100: resistor at the EL2008
input (R1) is necessary to stabilize the loop. The 100:
resistor at the EL2008 output (R2) to the -12V supply,
insures that the EL2008 sources current even when the
output voltage is at 0V. This is necessary to achieve the
excellent differential gain and phase values. More
information about driving cables can be found in the EL2003
data sheet. See the EL2020 data sheet to learn more about
using it as a multiplexer.
INPUT (TOP TRACE) AND OUTPUT (BOTTOM TRACE)
OF EHA2505 OP AMP BOOSTED BY EL2008.