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August 1995, Rev. A
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1-888
EL2090
FN7040
100MHz DC-Restored Video Amplifier
Features
The EL2090 is the first complete DCrestored monolithic video amplifier
sub-system. It contains a very highquality video amplifier and a nulling sample-and-hold
amplifier specifically designed to stabilize video
performance. When the HOLD logic input is set to a logic 0
during a horizontal sync, the sample-and-hold amplifier may
be used as a general-purpose op-amp to null the DC offset
of the video amplifier. When the HOLD input goes to a logic
1 the sample-and-hold stores the correction voltage on the
hold capacitor to maintain DC correction during the
subsequent scan line.
• Complete video level restoration system
The video amplifier is optimized for video characteristics,
and performance at NTSC is nearly perfect. It is a currentfeedback amplifier, so that -3dB bandwidth changes little at
various closed-loop gains. The amplifier easily drives video
signal levels into 75Ω loads. With 100MHz bandwidth, the
EL2090 is also useful in HDTV applications.
• TTL/CMOS hold signal
The sample-and-hold is optimized for fast sync pulse
response. The application circuit shown will restore the video
DC level in five scan lines, even if the HOLD pulse is only
2µs long. The output impedance of the sample-and-hold is
low and constant over frequency and load current so that the
performance of the video amplifier is not compromised by
connections to the DC restore circuitry.
Ordering Information
• 0.01% differential gain and 0.02° differential phase
accuracy at NTSC
• 100MHz bandwidth
• 0.1dB flatness to 20MHz
• Sample-and-hold has 15nA typical leakage and 1.5pC
charge injection
• System can acquire DC correction level in 10µs, or 5 scan
lines of 2µs each, to 1/2 IRE
• VS = ±5V to ±15V
Applications
• Input amplifier in video equipment
• Restoration amplifier in video mixers
PART
NUMBER
TEMP.
RANGE
PACKAGE
PKG. NO.
EL2090CN
0°C to +75°C
14-Pin PDIP
MDP0031
EL2090CM
0°C to +75°C
16-Pin SOL
MDP0027
The EL2090 is fabricated in Elantec's proprietary
Complementary Bipolar process which produces NPN and
PNP transistors with equivalent AC and DC performance.
The EL2090 is specified for operation over the 0°C to 75°C
temperature range.
Pinouts
EL2090
(14-PIN DIP)
TOP VIEW
1
EL2090
(16-PIN SOL)
TOP VIEW
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
1-888-INTERSIL or 321-724-7143 | Intersil (and design) is a registered trademark of Intersil Americas Inc.
Copyright © Intersil Americas Inc. 2003. All Rights Reserved. Elantec is a registered trademark of Elantec Semiconductor, Inc.
All other trademarks mentioned are the property of their respective owners.
EL2090
Absolute Maximum Ratings (TA = 25°C)
Voltage between V+ and V- . . . . . . . . . . . . . . . . . . . . . . . . . . . . .36V
Voltage between VIN+, S/HIN+, S/HIN-, CHOLD,
and GND pins (V+) . . . . . . . . . . . . . . . . . . . . . . . +0.5V to (V-) -0.5V
VOUT Current. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60mA
Current into VIN- and HOLD Pins . . . . . . . . . . . . . . . . . . . . . . . 5mA
Current S/HOUT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16mA
Internal Power Dissipation . . . . . . . . . . . . . . . . . . . . . . . See Curves
Operating Ambient Temperature Range . . . . . . . . . . . . 0°C to 75°C
Operating Junction Temperature Plastic DIP or SOL. . . . . . . . 150°C
Storage Temperature Range . . . . . . . . . . . . . . . . . .-65°C to +150°C
CAUTION: Stresses above those listed in “Absolute Maximum Ratings” may cause permanent damage to the device. This is a stress only rating and operation of the
device at these or any other conditions above those indicated in the operational sections of this specification is not implied.
IMPORTANT NOTE: All parameters having Min/Max specifications are guaranteed. Typical values are for information purposes only. Unless otherwise noted, all tests
are at the specified temperature and are pulsed tests, therefore: TJ = TC = TA
Open-Loop DC Electrical Specifications
PARAMETER
IS
VS = ±15V; RL = 150Ω, TA = 25°C unless otherwise specified
DESCRIPTION
TEMP
Total Supply Current
MIN
TYP
MAX
UNITS
Full
14
17
mA
VIDEO AMPLIFIER SECTION (NOT RESTORED)
VOS
Input Offset Voltage
Full
8
70
mV
IB+
+VIN Input Bias Current
Full
2
15
µA
IB-
-VIN Input Bias Current
Full
30
150
µA
ROL
Transimpedance
25°C
300
V/mA
AVOL
Open-Loop Voltage Gain; VOUT = ±2V
VO
Output Voltage Swing
ISC
Full
56
65
dB
VS = ±15V; RL = 2kΩ
Full
±12
±13
V
VS = ±5V; RL = 150Ω
Full
±3.0
±3.5
V
25°C
±50
±90
±160
mA
Short-Circuit Current; +VIN Set to ±2V; -VIN to Ground through 1kΩ
SAMPLE-AND-HOLD SECTION
VOS
Input Offset Voltage
Full
2
10
mV
IB
Input Bias Current
Full
0.5
2.5
µA
IOS
Input Offset Current
Full
0.05
0.5
µA
RIN, DIFF
Input Differential Resistance
25°C
200
kΩ
RIN, COMM
Input Common-Mode Resistance
25°C
100
MΩ
VCM
Common-Mode Input Range
Full
±11
±12.5
V
SAMPLE-AND-HOLD SECTION
AVOL
Large Signal Voltage Gain
Full
15k
50k
V/V
CMRR
Common-Mode Rejection Ratio; VCM = ±11V
Full
75
95
dB
PSRR
Power-Supply Rejection Ratio; VS = ±5V to ±15V
Full
75
95
dB
VTHRESH
HOLD Pin Logic Threshold
Full
0.8
1.4
2.0
V
IDROOP
Hold Mode Droop Current
Full
10
50
nA
ICHARGE
Charge Current Available to Chold
Full
±90
±135
µA
VO
Output Swing; RL = 2k
Full
±10
±13
V
ISC
Short-Circuit Current
25°C
±10
±17
2
±40
mA
EL2090
VS = ±15V; CL = 15pF; CSTRAY (-VIN) = 2.5pF; RF = RG = 300Ω; RL = 150Ω;
CHOLD = 100pF; TA = 25°C
Closed-Loop AC Electrical Specifications
PARAMETER
DESCRIPTION
MIN
TYP
MAX
UNITS
VIDEO AMPLIFIER SECTION
SR
SlewRate; VOUT from -2 to +2V
BW
Bandwidth;
600
V/µs
-3dB
75
100
MHz
±1dB
35
60
MHz
±0.1dB
10
20
MHz
dG (Peaking)
Differential Gain; VIN from -0.7V to 0.7V; F = 3.58MHz
0.01
%
dθ (Peaking)
Differential Phase; VIN from -0.7V to 0.7V; F = 3.58MHz
0.02
°
MHz
SAMPLE-AND-HOLD SECTION
BW
Gain-Bandwidth Product
1.3
Q
Sample to Hold Charge Injection (Note 1)
1.5
T
Sample to Hold or Hold to Sample Delay Time
20
ns
Ts
Sample to Hold Settling Time to 2mV
200
ns
5
pC
NOTE:
1. The logic input is between 0V and 5V, with a 220Ω resistor in series with the HOLD pin and 39pF capacitor from HOLD pin to ground.
3
EL2090
FIGURE 1. TYPICAL APPLICATION (AV = +2)
Typical Performance Curves
Relative Frequency Response
for Various Gains
Frequency Response Flatness
for Various Load
and Supply Conditions
4
Frequency Response with
Different Loads (AV = +2)
Frequency Response Flatness vs
CIN-, AV = +2
EL2090
Typical Performance Curves
(Continued)
Differential Gain and Phase vs
Supply Voltage; AV = +2,
RL = 150Ω, VIN from 0 to +0.7 VDC
Deviation from Linear
Phase vs Frequency
Differential Gain vs DC Input
Offset; AV = +2,
FO = 3.58MHz, RL = 150Ω
Differential Phase vs DC Input
Offset; AV = +2,
FO = 3.58MHz, RL = 150Ω
Differential Gain vs DC Input Offset;
AV = +2 and FO = 30MHz, RL = 150Ω
5
Differential Phase vs DC Input Offset;
AV = +2, FO = 30MHz, RL = 150Ω
EL2090
Typical Performance Curves
(Continued)
S/H Available Charge Current
vs Temperature
Sample-to-Hold Change
Injection vs Temperature
Typical Droop Current vs
Temperature, VS = ±15V
Supply Current vs
Supply Voltage
Supply Current vs Temperature;
VS = ±15V
Maximum Power Dissipation
vs Ambient Temperature—
14-Pin PDIP and 16-Pin SOL
6
EL2090
Applications Information
The EL2090 is a general purpose component and thus the
video amplifier and sample-and-hold pins are uncommitted.
Therefore much of the ultimate performance as a DCrestored video amplifier will be set by external component
values and parasitics. Some application considerations will
be offered here.
The DC feedback from the sample-and-hold can be applied
to either positive or negative inputs of the video amplifier
(with appropriate phasing of the sample-and-hold amplifier
inputs). We will consider feedback to the inverting video
input. During a sample mode (the HOLD input at a logic low),
the sample-and-hold acts as a simple nulling op-amp.
Ideally, the DC feedback resistor Raz is a high value so as
not to couple a large amount of the AC signal on the video
input back to the sample-and-hold amplifier output. The
sample-and-hold output is a low impedance at high
frequencies, but variations of the DC operating point will
change the output impedance somewhat. No more than a
few ohms output impedance change will occur, but this can
cause gain variations in the 0.01% realm. This DCdependent gain change is in fact a differential gain effect.
Some small differential phase error will also be added. The
best approach is to maximize the DC feedback resistor value
so as to isolate the sample-and-hold from the video path as
much as possible. Values of 1kΩ or above for Raz will cause
little to no video degradation.
This suggests that the largest applicable power supply
voltages be used so that the output swing of the sample-andhold can still correct for the variations of DC offset in the
video input with large values of Raz. The typical application
circuit shown will allow correction of ±1V inputs with good
isolation of the sample-and-hold output. Good isolation is
defined as no video degradation due to the insertion of the
sample-and-hold loop. Lower supply voltages will require a
smaller value of DC feedback resistor to retain correction of
the full input DC variation. The EL2090 differential phase
performance is optimum at ±9V supplies, and differential
gain only marginally improves above this voltage. Since all
video characteristics mildly degrade with increasing die
temperature, the ±9V levels are somewhat better than ±15V
supplies. However, ±15V supplies are quite usable.
Ultimate video performance, especially in HDTV
applications, can also be optimized by setting the black-level
reference such that the signal span at the video amplifier's
output is set to its optimum range. For instance, setting the
span to ±1V of output is preferable to a span of 0V to +2V.
The curves of differential gain and phase versus input DC
offset will serve as guides.
The DC feedback resistor may be split so that a bypass
capacitor is added to reduce the initially small sample-andhold transients to even smaller levels. The corruption can be
reduced to as low as 1mV peak seen at the video amplifier
7
output. The size of the capacitor should not be so large as to
de-stabilize the sample-and-hold feedback loop, nor so small
as to reduce the video amplifier's gain flatness. A resistor or
some other video isolation network should be inserted
between the video amplifier output and the sample-and-hold
input to prevent excessive video from bleeding through the
autozero section, as well as preventing spurious DC
correction due to video signals confusing the sample-andhold during autozero events. Figure 1 shows convenient
component values. A full 3.58MHz trap is not necessary for
suppressing NTSC chroma burst interaction with the
sample-and-hold input; the simple R-C network suggested in
Figure 1 suffices.
The HOLD input to the sample-and-hold has a 1.4V
threshold and is clamped to a diode below ground and 6V
above ground. The hold step characteristics are not sensitive
to logic high nor low levels (within TTL or CMOS swings), but
logic slewrates greater than 1000V/µs can couple noise and
hold step into the sample-to-hold output waveforms. The
logic slewrate should be greater than 50V/µs to avoid hold
jitter. To avoid artificially high droop in hold mode, the Chold
pin and Chold itself should be guarded with circuit board
traces connected to the output of the sample-and-hold. Lowleakage hold capacitors should be used, such as mica or
mylar, but not ceramic. The excellent properties of more
expensive polystyrene, polypropylene, or teflon capacitors
are not needed.
The user should be aware of a combination of conditions that
may make the EL2090 operate incorrectly upon power-up.
The fault condition can be described by noticing that the
sample-and-hold output (pin 11) appears locked at a voltage
close to VCC. This voltage is maintained regardless of
changes at the inputs to the sample-and-hold (pins 5 and 6)
or to the HOLD control input (pin 7). Two conditions must
occur to bring this about:
1. A large value of Chold_usually values of 1000pF or more.
This is not an unusual situation. Many users want to
reduce the size of the hold step and increasing Chold is
the most direct way to do this. Increasing Chold also
reduces the slew rate of the sample and hold section but
because of the limited size of the video signal, this is
usually not a limitation.
2. A sampling interval (dictated by the HOLD pin) that is too
small. By small, we mean less than 2µs.
For a sampling interval that is wide enough, there is enough
time for the loop to close and for the amplifier to discharge
whatever charge was dumped onto Chold it during the initial
power spike and to then ramp up (or down) to the voltage
that is proper for a balanced loop. When the sampling
interval is too small, there is insufficient time for internal
devices to recover from their initial saturated state from
power-up because the feedback is not closed long enough.
Therefore, typical recovery times for the loop are 2µs or
greater. Summarizing, the two things that could prevent
proper saturation recovery are (as mentioned above) too
EL2090
large a capacitor which slows the charge and discharge rate
of the stored voltage at Chold and too small a sampling
interval in which the entire feedback loop is closed.
The circuit shown above prevents the fault condition from
occurring by preventing the node from ever saturating. By
clamping the value of Chold to some value lower than the
supply voltage less a saturation voltage, we prevent this
node from approaching the positive rail. The maximum
voltage is set by the resistive voltage divider (between V+
and GND) R1 and R2 plus a diode. This value can be
adjusted if the maximum size of the input signal is known.
The diode used is an off-the-shelf 1N914 or 1N916.
As is true of all 100MHz amplifiers, good bypassing of the
supplies to ground is mandatory. 1µF tantalums are
sufficient, and 0.01µF leaded chip capacitors in parallel with
medium value electrolytics are also good. Pins longer than
1/2 can induce a characteristic 150MHz resonance and
ringing.
The VIN- of the video amplifier should have the absolute
minimum of parasitic capacitance. Stray capacitance of more
than 3pF will cause peaking and compromise the gain
flatness. The bandwidth of the amplifier is fundamentally set
by the value of Rf. As demonstrated by the frequency
response versus gain graph, the peaking and bandwidth is a
weak function of gain. The EL2090 was designed for
Rf = 300Ω giving optimum gain flatness at Av = +2. Unitygain response is flattest for Rf = 360Ω; gains of +5 can use
Rf = 270Ω. In situations where the peaking is accentuated by
load capacitance or -input capacitance the value of Rf will
have to be increased, and some bandwidth will be sacrificed.
The VIN+ of the video amplifier should not look into an
inductive source impedance. If the source is physically
remote and a terminated input line is not provided, it may be
necessary to connect an input “snubber” to ground. A
snubber is a resistor in series with a capacitor which de-Q's
the input resonance. Typical values are 100Ω and 30pF.
The output of the video amplifier is sensitive to capacitive
loads greater than 25pF, and a snubber to ground or a
resistor in series with the output is useful to isolate reactive
loads.
8
EL2090
EL2090 Macromodel
* Revision A, October 1992
.param vclamp = {-0.002 * (TEMP-25)}
*
* Connections:
Vidin+
*
|
Vidin*
|
|
+Vsupply
*
|
|
|
-Vsupply
*
|
|
|
|
Vid Out
*
|
|
|
|
|
S/H In+
*
|
|
|
|
|
|
S/H In*
|
|
|
|
|
|
|
S/H Out
*
|
|
|
|
|
|
|
|
Hold Control
*
|
|
|
|
|
|
|
|
|
Chold
*
|
|
|
|
|
|
|
|
|
|
.subckt EL2090/EL 3 1 14 12 13 5 6 11 7 9
*
******** Video Amplifier *******************
*
e1 20 0 3 0 1.0
vis 20 34 0V
h2 34 38 vxx 1.0
r10 1 36 25
l1 36 38 20nH
iinp 3 0 10µA
iinm 1 0 5µA
h1 21 0 vis 600
r2 21 22 1K
d1 22 0 dclamp
d2 0 22 dclamp
e2 23 0 22 0 0.00166666666
l5 23 24 0.7µH
c5 24 0 0.5pF
r5 24 0 600
g1 0 25 24 0 1.0
rol 25 0 400K
cdp 25 0 7.7pF
q1 12 25 26 qp
q2 14 25 27 qn
q3 14 26 28 qn
q4 12 27 29 qp
r7 28 13 4
r8 29 13 4
ios1 14 26 2.5mA
ios2 27 12 2.5mA
ips 14 12 7.2mA
ivos 0 33 5mA
vxx 33 0 0V
r11 33 0 1K
*
************ Sample & Hold *************************
*
g40 49 0 5 6 1e-3
vcur 49 42 0v
r43 6 0 100Meg
r44 5 0 100Meg
r40 42 0 4K
d41 50 42 diode
d42 42 51 diode
v41 50 0 {vclamp}
9
EL2090
EL2090 Macromodel
(Continued)
v42 0 51 {vclamp}
g41 44 0 42 0 200e-6
r42 44 0 31Meg
d45 9 14 diode
d46 12 9 diode
s1 44 9 48 0 swa
e40 46 0 9 0 0.95
i40 0 9 10nA
r45 46 47 70
l40 47 11 70nH
c40 7 9 0.32pF
r47 7 48 10K
c41 48 0 3pF
*
* Models
*
.model qn npn(is=5e-15 bf=500 tf=0.1nS)
.model qp pnp(is=5e-15 bf=500 tf=0.1nS)
.model dclamp d(is=1e-30 ibv=0.02 bv=2.75 n=4)
.model diode d
.model swa vswitch(von=1.2v voff=1.6v roff=1e12 ron=100)
.ends
10
EL2090
EL2090 Macromodel
(Continued)
FIGURE 2. SAMPLE AND HOLD AMPLIFIER
FIGURE 3. VIDEO AMPLIFIER
All Intersil U.S. products are manufactured, assembled and tested utilizing ISO9000 quality systems.
Intersil Corporation’s quality certifications can be viewed at www.intersil.com/design/quality
Intersil products are sold by description only. Intersil Corporation reserves the right to make changes in circuit design, software and/or specifications at any time without
notice. Accordingly, the reader is cautioned to verify that data sheets are current before placing orders. Information furnished by Intersil is believed to be accurate and
reliable. However, no responsibility is assumed by Intersil or its subsidiaries for its use; nor for any infringements of patents or other rights of third parties which may result
from its use. No license is granted by implication or otherwise under any patent or patent rights of Intersil or its subsidiaries.
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11