EL2090C
January
1996
Rev
D
EL2090C
100 MHz DC-Restored Video Amplifier
Note All information contained in this data sheet has been carefully checked and is believed to be accurate as of the date of publication however this data sheet cannot be a ``controlled document'' Current revisions if any to these
specifications are maintained at the factory and are available upon your request We recommend checking the revision level before finalization of your design documentation Patent pending
CMS
2090DS
1990 Elantec Inc
Features
Complete video level restoration
system
0 01% differential gain and 0 02
differential phase accuracy at
NTSC
100 MHz bandwidth
0 1 dB flatness to 20 MHz
Sample-and-hold has 15 nA
typical leakage and 1 5 pC charge
injection
System can acquire DC
correction level in 10
ms or 5 scan
lines of 2
ms each to
IRE
V
S
e
g
5V to
g
15V
TTL CMOS hold signal
Applications
Input amplifier in video
equipment
Restoration amplifier in video
mixers
Ordering Information
Part No
Temp Range
Pkg
Outline
EL2090CN 0 C to a75 C
14-Pin P-DIP MDP0031
EL2090CM 0 C to a75 C
16-Lead SOL MDP0027
General Description
The EL2090C is the first complete DC-restored monolithic vid-
eo amplifier sub-system It contains a very high-quality 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 in-
put 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
The video amplifier is optimized for video characteristics and
performance at NTSC is nearly perfect It is a current-feedback
amplifier so that
b
3 dB bandwidth changes little at various
closed-loop gains The amplifier easily drives video signal levels
into 75
X loads With 100 MHz bandwidth the EL2090 is also
useful in HDTV applications
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 2
ms 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
The EL2090C is fabricated in Elantec's proprietary Comple-
mentary Bipolar process which produces NPN and PNP tran-
sistors with equivalent AC and DC performance The EL2090C
is specified for operation over the 0 C to 75 C temperature
range
Connection Diagrams
14-Pin DIP Package
16-Pin SOL Package
2090 1
2090 2
EL2090C
100 MHz DC-Restored Video Amplifier
Absolute Maximum Ratings
(T
A
e
25 C)
Voltage between V
a
and V
b
36V
Voltage between V
INa
S H
INa
S H
INb
C
HOLD
and GND pins
(V
a
)
a
0 5V
to (V
b
)
b
0 5V
V
OUT
Current
60 mA
Current into V
INb
and HOLD Pins
5 mA
Current S H
OUT
16 mA
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
b
65 C to
a
150 C
Important Note
All parameters having Min Max specifications are guaranteed The Test Level column indicates the specific device testing actually
performed during production and Quality inspection Elantec performs most electrical tests using modern high-speed automatic test
equipment specifically the LTX77 Series system Unless otherwise noted all tests are pulsed tests therefore T
J
e
T
C
e
T
A
Test Level
Test Procedure
I
100% production tested and QA sample tested per QA test plan QCX0002
II
100% production tested at T
A
e
25 C and QA sample tested at T
A
e
25 C
T
MAX
and T
MIN
per QA test plan QCX0002
III
QA sample tested per QA test plan QCX0002
IV
Parameter is guaranteed (but not tested) by Design and Characterization Data
V
Parameter is typical value at T
A
e
25 C for information purposes only
Open Loop DC Electrical Characteristics
V
S
e
g
15V R
L
e
150
X T
A
e
25 C unless otherwise specified
Parameter
Description
Temp
Min
Typ
Max
Test Level
Units
I
S
Total Supply Current
Full
14
17
II
mA
Video Amplifier Section (Not Restored)
V
OS
Input Offset Voltage
Full
8
70
II
mV
I
Ba
a
V
IN
Input Bias Current
Full
2
15
II
mA
I
Bb
b
V
IN
Input Bias Current
Full
30
150
II
mA
R
OL
Transimpedance
25 C
300
V
V mA
A
VOL
Open-Loop Voltage Gain
Full
56
65
II
dB
V
OUT
e
g
2V
V
O
Output Voltage Swing
Full
g
12
g
13
II
V
V
S
e
g
15V R
L
e
2 k
X
V
S
e
g
5V R
L
e
150
X
Full
g
3 0
g
3 5
II
V
I
SC
Short-Circuit Current
a
V
IN
Set to
g
2V
b
V
IN
25 C
g
50
g
90
g
160
II
mA
to Ground through 1 k
X
Sample-And-Hold Section
V
OS
Input Offset Voltage
Full
2
10
II
mV
I
B
Input Bias Current
Full
0 5
2 5
II
mA
I
OS
Input Offset Current
Full
0 05
0 5
II
mA
R
IN DIFF
Input Differential Resistance
25 C
200
V
k
X
R
IN COMM
Input Common-Mode Resistance
25 C
100
V
M
X
V
CM
Common-Mode Input Range
Full
g
11
g
12 5
II
V
2
TD
is
39in
EL2090C
100 MHz DC-Restored Video Amplifier
Open Loop DC Electrical Characteristics
V
S
e
g
15V R
L
e
150
X T
A
e
25 C unless otherwise specified
Contd
Parameter
Description
Temp
Min
Typ
Max
Test Level
Units
Sample-And-Hold Section
Contd
A
VOL
Large Signal Voltage Gain
Full
15k
50k
II
V V
CMRR
Common-Mode Rejection Ratio
Full
75
95
II
dB
V
CM
e
g
11V
PSRR
Power-Supply Rejection Ratio
Full
75
95
II
dB
V
S
e
g
5V to
g
15V
V
thresh
HOLD Pin Logic Threshold
Full
0 8
1 4
2 0
II
V
I
droop
Hold Mode Droop Current
Full
10
50
II
nA
I
charge
Charge Current Available to
Full
g
90
g
135
II
mA
Chold
V
O
Output Swing R
L
e
2k
Full
g
10
g
13
II
V
I
SC
Short-Circuit Current
25 C
g
10
g
17
g
40
II
mA
Closed Loop AC Electrical Characteristics
V
S
e
g
15V C
L
e
15 pF C
stray
(
b
V
IN
)
e
2 5 pF R
F
e
R
G
e
300
X R
L
e
150
X C
hold
e
100 pF T
A
e
25 C
Parameter
Description
Min
Typ
Max
Test Level
Units
Video Amplifier Section
SR
SlewRate V
OUT
from
b
2 to
a
2V
600
V
V
ms
BW
Bandwidth
b
3 dB
75
100
III
MHz
g
1 dB
35
60
III
MHz
g
0 1 dB
10
20
III
MHz
Peaking
dG
Differential Gain
V
IN
from
b
0 7V to 0 7V
0 01
V
%
F
e
3 58 MHz
d
i
Differential Phase
V
IN
from
b
0 7V to 0 7V
0 02
V
F
e
3 58 MHz
Sample-And-Hold Section
BW
Gain-Bandwidth Product
1 3
V
MHz
DQ
Sample to Hold Charge
1 5
5
III
pC
Injection (Note 1)
DT
Sample to Hold or Hold to
20
V
ns
Sample Delay Time
T
s
Sample to Hold Settling
200
V
ns
Time to 2 mV
Note 1 The logic input is between 0V and 5V with a 220
X resistor in series with the HOLD pin and 39 pF capacitor from HOLD pin
to ground
3
TD
is
23in
TD
is
34in
EL2090C
100 MHz DC-Restored Video Amplifier
2090 3
Figure 1 Typical Application (A
V
e a
2)
Typical Performance Curves
for Various Gains
Relative Frequency Response
Different Loads (A
V
e
a
2)
Frequency Response with
2090 4
and Supply Conditions
for Various Load
Frequency Response Flatness
C
INb
A
V
e
a
2
Frequency Response Flatness vs
2090 5
4
EL2090C
100 MHz DC-Restored Video Amplifier
Typical Performance Curves
Contd
R
L
e
150X V
IN
from 0 to a0 7 V
DC
Supply Voltage A
V
e
a
2
Differential Gain and Phase vs
Phase vs Frequency
Deviation from Linear
F
O
e
3 58 MHz R
L
e
150X
Offset A
V
e
a
2
Differential Gain vs DC Input
F
O
e
3 58 MHz R
L
e
150X
Offset A
V
e
a
2
Differential Phase vs DC Input
2090 12
A
V
e
a
2 and F
O
e
30 MHz R
L
e
150X
Differential Gain vs DC Input Offset
A
V
e
a
2 F
O
e
30 MHz R
L
e
150X
Differential Phase vs DC Input Offset
2090 6
5
EL2090C
100 MHz DC-Restored Video Amplifier
Typical Performance Curves
Contd
vs Temperature
S H Available Charge Current
2090 7
Injection vs Temperature
Sample-to-Hold Change
Temperature V
S
e
g
15V
Typical Droop Current vs
2090 8
Supply Voltage
Supply Current vs
V
S
e
g
15V
Supply Current vs Temperature
2090 9
6
EL2090C
100 MHz DC-Restored Video Amplifier
Typical Performance Curves
Contd
Maximum Power Dissipation
vs Ambient Temperature
14-Pin PDIP and 16-Pin SOL
2090 10
Applications Information
The EL2090C 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 DC-restored video
amplifier will be set by external component val-
ues and parasitics Some application considera-
tions 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 log-
ic low) the sample-and-hold acts as a simple null-
ing 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
DC-dependent
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 feed-
back resistor value so as to isolate the sample-
and-hold from the video path as much as possi-
ble Values of 1 k
X 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-and-hold can still correct for the
variations of DC offset in the video input with
large values of Raz The typical application cir-
cuit shown will allow correction of
g
1V inputs
with good isolation of the sample-and-hold out-
put Good isolation is defined as no video degra-
dation 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 opti-
mum at
g
9V supplies and differential gain only
marginally improves above this voltage Since all
video characteristics mildly degrade with increas-
ing die temperature the
g
9V levels are some-
what better than
g
15V supplies
However
g
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
g
1V of
output is preferable to a span of 0V to
a
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-and-hold transients to even smaller
levels The corruption can be reduced to as low as
1 mV peak seen at the video amplifier 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 amplifi-
er'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 prevent-
ing spurious DC correction due to video signals
confusing the sample-and-hold during autozero
events Figure 1 shows convenient component
values A full 3 58 MHz trap is not necessary for
suppressing NTSC chroma burst interaction with
the sample-and-hold input the simple R-C net-
work suggested in Figure 1 suffices
7
EL2090C
100 MHz DC-Restored Video Amplifier
Applications Information
Contd
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 char-
acteristics are not sensitive to logic high nor low
levels (within TTL or CMOS swings) but logic
slewrates greater than 1000V
ms can couple noise
and hold step into the sample-to-hold output
waveforms The logic slewrate should be greater
than 50V
ms to avoid hold jitter To avoid artifi-
cially high droop in hold mode the Chold pin
and Chold itself should be guarded with circuit
board traces connected to the output of the sam-
ple-and-hold Low-leakage hold capacitors should
be used such as mica or mylar but not ceramic
The excellent properties of more expensive poly-
styrene polypropylene or teflon capacitors are
not needed
The user should be aware of a combination of
conditions that may make the EL2090 operate in-
correctly 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 V
CC
This voltage is maintained regard-
less 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
1000 pF or more This is not an unusual situa-
tion Many users want to reduce the size of the
hold step and increasing Chold is the most di-
rect way to do this Increasing Chold also re-
duces the slew rate of the sample and hold sec-
tion but because of the limited size of the vid-
eo 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 2
ms
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 volt-
age that is proper for a balanced loop When the
sampling interval is too small there is insuffi-
cient time for internal devices to recover from
their initial saturated state from power-up be-
cause the feedback is not closed long enough
Therefore typical recovery times for the loop are
2
ms or greater Summarizing the two things
that could prevent proper saturation recovery are
(as mentioned above) too large a capacitor which
slows the charge and discharge rate of the stored
voltage at Chold and too small a sampling inter-
val in which the entire feedback loop is closed
The circuit shown below prevents the fault condi-
tion from occurring by preventing the node from
ever saturating By clamping the value of Chold
to some value lower than the supply voltage less
2090 13
8
EL2090C
100 MHz DC-Restored Video Amplifier
Applications Information
Contd
a saturation voltage we prevent this node from
approaching the positive rail
The maximum
voltage is set by the resistive voltage divider (be-
tween V
a
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 100 MHz amplifiers good by-
passing of the supplies to ground is mandatory
1
mF tantalums are sufficient and 0 01 mF leaded
chip capacitors in parallel with medium value
electrolytics are also good Leads longer than
can induce a characteristic 150 MHz resonance
and ringing
The V
IN
b
of the video amplifier should have the
absolute minimum of parasitic capacitance Stray
capacitance of more than 3 pF will cause peaking
and compromise the gain flatness The band-
width of the amplifier is fundamentally set by
the value of Rf As demonstrated by the frequen-
cy response versus gain graph the peaking and
bandwidth is a weak function of gain
The
EL2090 was designed for Rf
e
300
X giving opti-
mum gain flatness at Av
e
a
2 Unity-gain re-
sponse is flattest for Rf
e
360
X gains of
a
5 can
use Rf
e
270
X In situations where the peaking
is accentuated by load capacitance or
b
input ca-
pacitance the value of Rf will have to be in-
creased and some bandwidth will be sacrificed
The V
IN
a
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 re-
sistor in series with a capacitor which de-Q's the
input resonance Typical values are 100
X and
30 pF
The output of the video amplifier is sensitive to
capacitive loads greater than 25 pF and a snub-
ber to ground or a resistor in series with the out-
put is useful to isolate reactive loads
9
EL2090C
100 MHz DC-Restored Video Amplifier
EL2090 Macromodel
Revision A October 1992
param vclamp
e
b
0 002
(TEMP
b
25)
Connections
Vidin
a
l
Vidin
b
l
l
a
Vsupply
l
l
l
b
Vsupply
l
l
l
l
Vid Out
l
l
l
l
l
S H In
a
l
l
l
l
l
l
S H In
b
l
l
l
l
l
l
l
S H Out
l
l
l
l
l
l
l
l
Hold Control
l
l
l
l
l
l
l
l
l
Chold
l
l
l
l
l
l
l
l
l
l
subckt EL2090 EL 3
1
14
12
13
5
6
11
7
9
Video Amplifier
Sample
Hold
e1 20 0 3 0 1 0
g40 49 0 5 6 1e-3
vis 20 34 0V
vcur 49 42 0v
h2 34 38 vxx 1 0
r43 6 0 100Meg
r10 1 36 25
r44 5 0 100Meg
l1 36 38 20nH
r40 42 0 4K
iinp 3 0 10
mA
d41 50 42 diode
iinm 1 0 5
mA
d42 42 51 diode
h1 21 0 vis 600
v41 50 0 vclamp
r2 21 22 1K
v42 0 51 vclamp
d1 22 0 dclamp
g41 44 0 42 0 200e-6
d2 0 22 dclamp
r42 44 0 31Meg
e2 23 0 22 0 0 00166666666
d45 9 14 diode
l5 23 24 0 7
mH
d46 12 9 diode
c5 24 0 0 5pF
s1 44 9 48 0 swa
r5 24 0 600
e40 46 0 9 0 0 95
g1 0 25 24 0 1 0
i40 0 9 10nA
rol 25 0 400K
r45 46 47 70
cdp 25 0 7 7pF
l40 47 11 70nH
q1 12 25 26 qp
c40 7 9 0 32pF
q2 14 25 27 qn
r47 7 48 10K
q3 14 26 28 qn
c41 48 0 3pF
q4 12 27 29 qp
r7 28 13 4
Models
r8 29 13 4
ios1 14 26 2 5mA
model qn npn(is
e
5e-15 bf
e
500 tf
e
0 1nS)
ios2 27 12 2 5mA
model qp pnp(is
e
5e-15 bf
e
500 tf
e
0 1nS)
ips 14 12 7 2mA
model dclamp d(is
e
1e-30 ibv
e
0 02 bv
e
2 75 n
e
4)
ivos 0 33 5mA
model diode d
vxx 33 0 0V
model swa vswitch(von
e
1 2v voff
e
1 6v roff
e
1e12 ron
e
100)
r11 33 0 1K
ends
10
TD
is
66in
EL2090C
100 MHz DC-Restored Video Amplifier
EL2090 Macromodel
Contd
2090 15
Sample and Hold Amplifier
11
EL2090C
January
1996
Rev
D
EL2090C
100 MHz DC-Restored Video Amplifier
EL2090 Macromodel
Contd
2090 14
Video Amplifier
General Disclaimer
Specifications contained in this data sheet are in effect as of the publication date shown Elantec Inc reserves the right to make changes
in the circuitry or specifications contained herein at any time without notice Elantec Inc assumes no responsibility for the use of any
circuits described herein and makes no representations that they are free from patent infringement
Elantec Inc
1996 Tarob Court
Milpitas CA 95035
Telephone (408) 945-1323
(800) 333-6314
Fax (408) 945-9305
European Office 44-71-482-4596
WARNING
Life Support Policy
Elantec Inc products are not authorized for and should not be
used within Life Support Systems without the specific written
consent of Elantec Inc Life Support systems are equipment in-
tended to support or sustain life and whose failure to perform
when properly used in accordance with instructions provided can
be reasonably expected to result in significant personal injury or
death Users contemplating application of Elantec Inc products
in Life Support Systems are requested to contact Elantec Inc
factory headquarters to establish suitable terms
conditions for
these applications Elantec Inc 's warranty is limited to replace-
ment of defective components and does not cover injury to per-
sons or property or other consequential damages
Printed in U S A
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