LMH6715EP
Enhanced Plastic Dual Wideband Video Op Amp
General Description
The LMH6715EP combines National’s VIP10™high speed
complementary bipolar process with National’s current feed-
back topology to produce a very high speed dual op amp.
The LMH6715EP provides 400MHz small signal bandwidth
at a gain of +2V/V and 1300V/µs slew rate while consuming
only 5.8mA per amplifier from ±5V supplies.
The LMH6715EP offers exceptional video performance with
its 0.02% and 0.02˚ differential gain and phase errors for
NTSC and PAL video signals while driving up to four back
terminated 75Ωloads. The LMH6715EP also offers a flat
gain response of 0.1dB to 100MHz and very low channel-to-
channel crosstalk of −70dB at 10MHz. Additionally, each
amplifier can deliver 70mA of output current. This level of
performance makes the LMH6715EP an ideal dual op amp
for high density, broadcast quality video systems.
The LMH6715EP’s two very well matched amplifiers support
a number of applications such as differential line drivers and
receivers. In addition, the LMH6715EP is well suited for
Sallen Key active filters in applications such as anti-aliasing
filters for high speed A/D converters. Its small 8-pin SOIC
package, low power requirement, low noise and distortion
allow the LMH6715EP to serve portable RF applications
such as IQ channels.
ENHANCED PLASTIC
•Extended Temperature Performance of −40˚C to +85˚C
•Baseline Control - Single Fab & Assembly Site
•Process Change Notification (PCN)
•Qualification & Reliability Data
•Solder (PbSn) Lead Finish is standard
•Enhanced Diminishing Manufacturing Sources (DMS)
Support
Features
nT
A
= 25˚C, R
L
= 100Ω, typical values unless specified.
nVery low diff. gain, phase: 0.02%, 0.02˚
nWide bandwidth: 480MHz (A
V
= +1V/V); 400MHz (A
V
=
+2V/V)
n0.1dB gain flatness to 100MHz
nLow power: 5.8mA/channel
n−70dB channel-to-channel crosstalk (10MHz)
nFast slew rate: 1300V/µs
nUnity gain stable
nImproved replacement for CLC412
Applications
nSelected Military Applications
nSelected Avionics Applications
Ordering Information
PART NUMBER VID PART NUMBER NS PACKAGE NUMBER (Note 3)
LMH6715MAEP V62/04623-01 M08A
(Notes 1, 2) TBD TBD
Note 1: For the following (Enhanced Plastic) version, check for availability: LMH6715MAXEP. Parts listed with an "X" are provided in Tape & Reel
and parts without an "X" are in Rails.
Note 2: FOR ADDITIONAL ORDERING AND PRODUCT INFORMATION, PLEASE VISIT THE ENHANCED PLASTIC WEB SITE AT: www.national.com/
mil
Note 3: Refer to package details under Physical Dimensions
May 2004
LMH6715EP Enhanced Plastic Dual Wideband Video Op Amp
© 2004 National Semiconductor Corporation DS200885 www.national.com
Differential Gain & Phase with
Multiple Video Loads
20088508
Frequency Response vs. V
OUT
20088516
LMH6715EP Enhanced Plastic
www.national.com 2
Absolute Maximum Ratings (Note 4)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
ESD Tolerance (Note 7)
Human Body Model 2000V
Machine Model 150V
V
CC
±6.75V
I
OUT
(Note 6)
Common-Mode Input Voltage ±V
CC
Differential Input Voltage 2.2V
Maximum Junction Temperature +150˚C
Storage Temperature Range −65˚C to +150˚C
Lead Temperature (Soldering 10
sec)
+300˚C
Operating Ratings
Thermal Resistance
Package (θ
JC
)(θ
JA
)
SOIC 65˚C/W 145˚C/W
Operating Temperature Range −40˚C to +85˚C
Nominal Operating Voltage ±5V to ±6V
Electrical Characteristics
A
V
= +2, R
F
= 500Ω,V
CC
=±5V,R
L
= 100Ω; unless otherwise specified. Boldface limits apply at the temperature extremes.
Symbol Parameter Conditions Min Typ Max Units
Frequency Domain Response
SSBW -3dB Bandwidth V
OUT
<0.5V
PP
,R
F
= 300Ω280 400 MHz
LSBW -3dB Bandwidth V
OUT
<4.0V
PP
,R
F
= 300Ω170 MHz
Gain Flatness V
OUT
<0.5V
PP
GFP Peaking DC to 100MHz, R
F
= 300Ω0.1 dB
GFR Rolloff DC to 100MHz, R
F
= 300Ω0.1 dB
LPD Linear Phase Deviation DC to 100MHz, R
F
= 300Ω0.25 deg
DG Differential Gain R
L
= 150Ω, 4.43MHz 0.02 %
DP Differential Phase R
L
= 150Ω, 4.43MHz 0.02 deg
Time Domain Response
Tr Rise and Fall Time 0.5V Step 1.4 ns
4V Step 3 ns
Ts Settling Time to 0.05% 2V Step 12 ns
OS Overshoot 0.5V Step 1 %
SR Slew Rate 2V Step 1300 V/µs
Distortion And Noise Response
HD2 2nd Harmonic Distortion 2V
PP
, 20MHz −60 dBc
HD3 3rd Harmonic Distortion 2V
PP
, 20MHz −75 dBc
Equivalent Input Noise
V
N
Non-Inverting Voltage >1MHz 3.4 nV/
I
N
Inverting Current >1MHz 10.0 pA/
I
NN
Non-Inverting Current >1MHz 1.4 pA/
SNF Noise Floor >1MHz −153 dB
1Hz
XTLKA Crosstalk Input Referred 10MHz −70 dB
Static, DC Performance
V
IO
Input Offset Voltage ±2±6
±8
mV
DV
IO
Average Drift ±30 µV/˚C
I
BN
Input Bias Current Non-Inverting ±5±12
±20
µA
DI
BN
Average Drift ±30 nA/˚C
I
BI
Input Bias Current Inverting ±6±21
±35
µA
DI
BI
Average Drift ±20 nA/˚C
PSRR Power Supply Rejection Ratio DC 46
44
60 dB
LMH6715EP Enhanced Plastic
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Electrical Characteristics (Continued)
A
V
= +2, R
F
= 500Ω,V
CC
=±5V,R
L
= 100Ω; unless otherwise specified. Boldface limits apply at the temperature extremes.
Symbol Parameter Conditions Min Typ Max Units
CMRR Common Mode Rejection Ratio DC 50
47
56 dB
I
CC
Supply Current per Amplifier R
L
=∞4.7
4.1
5.8 7.6
8.1
mA
Miscellaneous Performance
R
IN
Input Resistance Non-Inverting 1000 kΩ
C
IN
Input Capacitance Non-Inverting 1.0 pF
R
OUT
Output Resistance Closed Loop .06 Ω
V
O
Output Voltage Range R
L
=∞±4.0 V
V
OL
R
L
= 100Ω±3.5
±3.4
±3.9 V
CMIR Input Voltage Range Common Mode ±2.2 V
I
O
Output Current 70 mA
Note 4: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is
intended to be functional, but specific performance is not guaranteed. For guaranteed specifications, see the Electrical Characteristics tables.
Note 5: Electrical Table values apply only for factory testing conditions at the temperature indicated. Factory testing conditions result in very limited self-heating of
the device such that TJ=T
A. No guarantee of parametric performance is indicated in the electrical tables under conditions of internal self heating where TJ>TA.
See Applications Section for information on temperature de-rating of this device." Min/Max ratings are based on product characterization and simulation. Individual
parameters are tested as noted.
Note 6: The maximum output current (IOUT) is determined by device power dissipation limitations. See the Power Dissipation section of the Application Division for
more details.
Note 7: Human body model, 1.5kΩin series with 100pF. Machine model, 0ΩIn series with 200pF.
Connection Diagram
8-Pin SOIC
20088504
Top View
LMH6715EP Enhanced Plastic
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Typical Performance Characteristics (T
A
= 25˚C, V
CC
=±5V, A
V
=±2V/V, R
F
= 500Ω,R
L
= 100Ω,
unless otherwise specified).
Non-Inverting Frequency Response Inverting Frequency Response
20088513 20088512
Non-Inverting Frequency Response vs. V
OUT
Small Signal Channel Matching
20088516 20088501
Frequency Response vs. Load Resistance Non-Inverting Frequency Response vs. R
F
20088515 20088514
LMH6715EP Enhanced Plastic
www.national.com5
Typical Performance Characteristics (T
A
= 25˚C, V
CC
=±5V, A
V
=±2V/V, R
F
= 500Ω,R
L
= 100Ω,
unless otherwise specified). (Continued)
Small Signal Pulse Response Large Signal Pulse Response
20088518 20088519
Input-Referred Crosstalk Settling Time vs. Accuracy
20088507 20088524
−3dB Bandwidth vs. V
OUT
DC Errors vs. Temperature
20088525 20088526
LMH6715EP Enhanced Plastic
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Typical Performance Characteristics (T
A
= 25˚C, V
CC
=±5V, A
V
=±2V/V, R
F
= 500Ω,R
L
= 100Ω,
unless otherwise specified). (Continued)
Open Loop Transimpedance, Z(s) Equivalent Input Noise vs. Frequency
20088520 20088523
Differential Gain & Phase vs. Load Differential Gain vs. Frequency
20088508 20088509
Differential Phase vs. Frequency Gain Flatness & Linear Phase Deviation
20088510 20088511
LMH6715EP Enhanced Plastic
www.national.com7
Typical Performance Characteristics (T
A
= 25˚C, V
CC
=±5V, A
V
=±2V/V, R
F
= 500Ω,R
L
= 100Ω,
unless otherwise specified). (Continued)
2nd Harmonic Distortion vs. Output Voltage 3rd Harmonic Distortion vs. Output Voltage
20088502 20088505
Closed Loop Output Resistance PSRR & CMRR
20088506 20088517
Suggested R
S
vs. C
L
20088527
LMH6715EP Enhanced Plastic
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Application Section
Application Introduction
Offered in an 8-pin package for reduced space and cost, the
wideband LMH6715EP dual current-feedback op amp pro-
vides closely matched DC and AC electrical performance
characteristics making the part an ideal choice for wideband
signal processing. Applications such as broadcast quality
video systems, IQ amplifiers, filter blocks, high speed peak
detectors, integrators and transimedance amplifiers will all
find superior performance in the LMH6715EP dual op amp.
FEEDBACK RESISTOR SELECTION
One of the key benefits of a current feedback operational
amplifier is the ability to maintain optimum frequency re-
sponse independent of gain by using appropriate values for
the feedback resistor (R
F
). The Electrical Characteristics and
Typical Performance plots specify an R
F
of 500Ω, a gain of
+2V/V and ±5V power supplies (unless otherwise specified).
Generally, lowering R
F
from it’s recommended value will
peak the frequency response and extend the bandwidth
while increasing the value of R
F
will cause the frequency
response to roll off faster. Reducing the value of R
F
too far
below it’s recommended value will cause overshoot, ringing
and, eventually, oscillation.
Frequency Response vs. R
F
20088514
The plot labeled “Frequency Response vs. R
F
” shows the
LMH6715EP’s frequency response as R
F
is varied (R
L
=
100Ω,A
V
= +2). This plot shows that an R
F
of 200Ωresults
in peaking and marginal stability. An R
F
of 300Ωgives near
maximal bandwidth and gain flatness with good stability, but
with very light loads (R
L
>300Ω) the device may show some
peaking. An R
F
of 500Ωgives excellent stability with good
bandwidth and is the recommended value for most applica-
tions. Since all applications are slightly different it is worth
some experimentation to find the optimal R
F
for a given
circuit. For more information see Application Note OA-13
which describes the relationship between R
F
and closed-
loop frequency response for current feedback operational
amplifiers.
When configuring the LMH6715EP for gains other than
+2V/V, it is usually necessary to adjust the value of the
feedback resistor. The two plots labeled “R
F
vs. Non-
inverting Gain” and “R
F
vs. Inverting Gain” provide recom-
mended feedback resistor values for a number of gain se-
lections.
20088535
FIGURE 1. Non-Inverting Configuration with Power
Supply Bypassing
20088537
FIGURE 2. Inverting Configuration with Power Supply
Bypassing
LMH6715EP Enhanced Plastic
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Application Introduction (Continued)
R
F
vs. Non-Inverting Gain
20088521
Both plots show the value of R
F
approaching a minimum
value (dashed line) at high gains. Reducing the feedback
resistor below this value will result in instability and possibly
oscillation. The recommended value of R
F
is depicted by the
solid line, which begins to increase at higher gains. The
reason that a higher R
F
is required at higher gains is the
need to keep R
G
from decreasing too far below the output
impedance of the input buffer. For the LMH6715EP the
output resistance of the input buffer is approximately 160Ω
and 50Ωis a practical lower limit for R
G
. Due to the limita-
tions on R
G
the LMH6715EP begins to operate in a gain
bandwidth limited fashion for gains of ±5V/V or greater.
R
F
vs. Inverting Gain
20088522
When using the LMH6715EP as a replacement for the
CLC412, identical bandwidth can be obtained by using an
appropriate value of R
F
. The chart “Frequency Response
vs. R
F
” shows that an R
F
of approximately 700Ωwill provide
bandwidth very close to that of the CLC412. At other gains a
similar increase in R
F
can be used to match the new and old
parts.
CIRCUIT LAYOUT
With all high frequency devices, board layouts with stray
capacitances have a strong influence over AC performance.
The LMH6715EP is no exception and its input and output
pins are particularly sensitive to the coupling of parasitic
capacitances (to AC ground) arising from traces or pads
placed too closely (<0.1”) to power or ground planes. In
some cases, due to the frequency response peaking caused
by these parasitics, a small adjustment of the feedback
resistor value will serve to compensate the frequency re-
sponse. Also, it is very important to keep the parasitic ca-
pacitance across the feedback resistor to an absolute mini-
mum.
The performance plots in the data sheet can be reproduced
using the evaluation boards available from National. The
CLC730036 board uses all SMT parts for the evaluation of
the LMH6715EP. The board can serve as an example layout
for the final production printed circuit board.
Care must also be taken with the LMH6715EP’s layout in
order to achieve the best circuit performance, particularly
channel-to-channel isolation. The decoupling capacitors
(both tantalum and ceramic) must be chosen with good high
frequency characteristics to decouple the power supplies
and the physical placement of the LMH6715EP’s external
components is critical. Grouping each amplifier’s external
components with their own ground connection and separat-
ing them from the external components of the opposing
channel with the maximum possible distance is recom-
mended. The input (R
IN
) and gain setting resistors (R
F
) are
the most critical. It is also recommended that the ceramic
decoupling capacitor (0.1µF chip or radial-leaded with low
ESR) should be placed as closely to the power pins as
possible.
POWER DISSIPATION
Follow these steps to determine the Maximum power dissi-
pation for the LMH6715EP:
1. Calculate the quiescent (no-load) power: P
AMP
=I
CC
(V
CC
-V
EE
)
2. Calculate the RMS power at the output stage: P
O
=(V
CC
-V
LOAD
)(I
LOAD
), where V
LOAD
and I
LOAD
are the voltage and
current across the external load.
3. Calculate the total RMS power: Pt = P
AMP
+P
O
The maximum power that the LMH6715EP, package can
dissipate at a given temperature can be derived with the
following equation:
Pmax = (150o- Tamb)/ θ
JA
, where Tamb = Ambient tempera-
ture (˚C) and θ
JA
= Thermal resistance, from junction to
ambient, for a given package (˚C/W). For the SOIC package
θ
JA
is 145˚C/W.
MATCHING PERFORMANCE
With proper board layout, the AC performance match be-
tween the two LMH6715EP’s amplifiers can be tightly con-
trolled as shown in Typical Performance plot labeled “Small-
Signal Channel Matching”.
The measurements were performed with SMT components
using a feedback resistor of 300Ωat a gain of +2V/V.
The LMH6715EP’s amplifiers, built on the same die, provide
the advantage of having tightly matched DC characteristics.
SLEW RATE AND SETTLING TIME
One of the advantages of current-feedback topology is an
inherently high slew rate which produces a wider full power
bandwidth. The LMH6715EP has a typical slew rate of
1300V/µs. The required slew rate for a design can be calcu-
lated by the following equation: SR = 2πfV
pk
.
LMH6715EP Enhanced Plastic
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Application Introduction (Continued)
Careful attention to parasitic capacitances is critical to
achieving the best settling time performance. The
LMH6715EP has a typical short term settling time to 0.05%
of 12ns for a 2V step. Also, the amplifier is virtually free of
any long term thermal tail effects at low gains.
When measuring settling time, a solid ground plane should
be used in order to reduce ground inductance which can
cause common-ground-impedance coupling. Power supply
and ground trace parasitic capacitances and the load ca-
pacitance will also affect settling time.
Placing a series resistor (R
s
) at the output pin is recom-
mended for optimal settling time performance when driving a
capacitive load. The Typical Performance plot labeled “R
S
and Settling Time vs. Capacitive Load” provides a means for
selecting a value of R
s
for a given capacitive load.
DC & NOISE PERFORMANCE
A current-feedback amplifier’s input stage does not have
equal nor correlated bias currents, therefore they cannot be
canceled and each contributes to the total DC offset voltage
at the output by the following equation:
The input resistance is the resistance looking from the non-
inverting input back toward the source. For inverting DC-
offset calculations, the source resistance seen by the input
resistor R
g
must be included in the output offset calculation
as a part of the non-inverting gain equation. Application note
OA-7 gives several circuits for DC offset correction. The
noise currents for the inverting and non-inverting inputs are
graphed in the Typical Performance plot labeled “Equivalent
Input Noise”. A more complete discussion of amplifier input-
referred noise and external resistor noise contribution can be
found in OA-12.
DIFFERENTIAL GAIN & PHASE
The LMH6715EP can drive multiple video loads with very
low differential gain and phase errors. The Typical Perfor-
mance plots labeled “Differential Gain vs. Frequency” and
“Differential Phase vs. Frequency” show performance for
loads from 1 to 4. The Electrical Characteristics table also
specifies performance for one 150Ωload at 4.43MHz. For
NTSC video, the performance specifications also apply. Ap-
plication note OA-24 “Measuring and Improving Differential
Gain & Differential Phase for Video”, describes in detail the
techniques used to measure differential gain and phase.
I/O VOLTAGE & OUTPUT CURRENT
The usable common-mode input voltage range (CMIR) of
the LMH6715EP specified in the Electrical Characteristics
table of the data sheet shows a range of ±2.2 volts. Exceed-
ing this range will cause the input stage to saturate and clip
the output signal.
The output voltage range is determined by the load resistor
and the choice of power supplies. With ±5 volts the class A/B
output driver will typically drive ±3.9V into a load resistance
of 100Ω. Increasing the supply voltages will change the
common-mode input and output voltage swings while at the
same time increase the internal junction temperature.
Applications Circuits
SINGLE-TO-DIFFERENTIAL LINE DRIVER
The LMH6715EP’s well matched AC channel-response al-
lows a single-ended input to be transformed to highly
matched push-pull driver. From a 1V single-ended input the
circuit of Figure 3 produces 1V differential signal between
the two outputs. For larger signals the input voltage divider
(R
1
=2R
2
) is necessary to limit the input voltage on channel
2.
DIFFERENTIAL LINE RECEIVER
Figure 4 and Figure 5 show two different implementations of
an instrumentation amplifier which convert differential sig-
nals to single-ended. Figure 5 allows CMRR adjustment
through R
2
.
20088545
FIGURE 3. Single-to-Differential Line Driver
20088546
FIGURE 4. Differential Line Receiver
LMH6715EP Enhanced Plastic
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Applications Circuits (Continued)
NON-INVERTING CURRENT-FEEDBACK INTEGRATOR
The circuit of Figure 6 achieves its high speed integration by
placing one of the LMH6715EP’s amplifiers in the feedback
loop of the second amplifier configured as shown.
LOW NOISE WIDE-BANDWIDTH TRANSIMPEDANCE
AMPLIFIER
Figure 7 implements a low noise transimpedance amplifier
using both channels of the LMH6715EP. This circuit takes
advantage of the lower input bias current noise of the non-
inverting input and achieves negative feedback through the
second LMH6715EP channel. The output voltage is set by
the value of R
F
while frequency compensation is achieved
through the adjustment of R
T
.
20088547
FIGURE 5. Differential Line Receiver with CMRR
Adjustment
20088549
FIGURE 6. Current Feedback Integrator
20088550
FIGURE 7. Low-Noise, Wide Bandwidth,
Transimpedance Amp.
LMH6715EP Enhanced Plastic
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Physical Dimensions inches (millimeters)
unless otherwise noted
8-Pin SOIC
NS Package Number M08A
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NATIONAL’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT
DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT AND GENERAL
COUNSEL OF NATIONAL SEMICONDUCTOR CORPORATION. As used herein:
1. Life support devices or systems are devices or
systems which, (a) are intended for surgical implant
into the body, or (b) support or sustain life, and
whose failure to perform when properly used in
accordance with instructions for use provided in the
labeling, can be reasonably expected to result in a
significant injury to the user.
2. A critical component is any component of a life
support device or system whose failure to perform
can be reasonably expected to cause the failure of
the life support device or system, or to affect its
safety or effectiveness.
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Stewardship Specification (CSP-9-111C2) and the Banned Substances and Materials of Interest Specification
(CSP-9-111S2) and contain no ‘‘Banned Substances’’ as defined in CSP-9-111S2.
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LMH6715EP Enhanced Plastic Dual Wideband Video Op Amp
National does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and National reserves the right at any time without notice to change said circuitry and specifications.
