Elantec EL4094CN Video gain control/fader Datasheet

EL4094C
EL4094C
Video Gain Control/Fader
Features
General Description
# Complete video fader
# 0.02%/0.04§ differential gain/
phase @ 100% gain
# Output amplifier included
# Calibrated linear gain control
# g 5V to g 15V operation
# 60 MHz bandwidth
# Low thermal errors
The EL4094C is a complete two-input fader. It combines two
inputs according to the equation:
Applications
#
#
#
#
#
Video faders/wipers
Gain control
Video text insertion
Level adjust
Modulation
VOUT e VINA (0.5V a Vg) a VINB (0.5V b Vg),
where VGAIN is the difference between VGAIN and VGAIN pin
voltages and ranges from b 0.5V to a 0.5V. It has a wide 60
MHz bandwidth at b 3 dB, and is designed for excellent video
distortion performance. The EL4094C is the same circuit as the
EL4095, but with feedback resistors included on-chip to implement unity-gain connection. An output buffer is included in
both circuits.
The gain-control input is also very fast, with a 20 MHz smallsignal bandwidth and 70 ns recovery time from overdrive.
The EL4094C is compatible with power supplies from g 5V to
g 15V, and is available in both the 8-pin plastic DIP and SO-8.
Ordering Information
Part No.
Temp. Range
Package
OutlineÝ
Connection Diagram
EL4094CN b 40§ C to a 85§ C 8-Pin P-DIP MDP0031
EL4094CS
b 40§ C to a 85§ C 8-Pin SO
MDP0027
Manufactured under U.S. Patent No. 5,321,371, 5,374,898
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.
© 1993 Elantec, Inc.
August 1996, Rev D
4094 – 1
EL4094C
Video Gain Control/Fader
Voltage between VS a and GND
Voltage between VS a and VSb
Input Voltage
VS a
VS
VINA,
VINB
VGAIN
VGAIN
a 18V
a 33V
(VSb) b0.3V
to (VS a ) a 0.3V
Input Voltage
Input Voltage
IOUT
Output Current
Internal Power Dissipation
TA
Operating Ambient Temp. Range
TJ
Operating Junction Temperature
TST
Storage Temperature Range
VGAIN g 5V
VSb to VS a
g 35 mA
See Curves
b 40§ C to a 85§ C
150§ C
b 65§ C to a 150§ C
TD is 0.6in
Absolute Maximum Ratings (TA e 25§ 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 TJ e TC e TA.
Test Level
I
II
III
IV
V
Test Procedure
100% production tested and QA sample tested per QA test plan QCX0002.
100% production tested at TA e 25§ C and QA sample tested at TA e 25§ C ,
TMAX and TMIN per QA test plan QCX0002.
QA sample tested per QA test plan QCX0002.
Parameter is guaranteed (but not tested) by Design and Characterization Data.
Parameter is typical value at TA e 25§ C for information purposes only.
Open Loop DC Electrical Characteristics
Parameter
Limits
Description
Min
VOS
Input Offset Voltage
IB a
VIN Input Bias Current
PSRR
Power Supply Rejection Ratio
EG
Gain Error, 100% Setting
60
Max
Test
Level
Units
Typ
4
30
I
mV
2
10
I
mA
I
dB
b 0.8
I
%
(V a ) b2.5
I
V
(V a ) b2.5
I
V
150
I
mA
80
b 0.5
VIN
VIN Range
(Vb) a 2.5
VO
Output Voltage Swing
(Vb) a 2.5
ISC
Output Short-Circuit Current
VGAIN, 100%
Minimum Voltage at VGAIN for 100% Gain
VGAIN, 0%
Maximum Voltage at VGAIN for 0% Gain
NL, Gain
50
95
0.45
0.5
0.55
I
V
b 0.55
b 0.5
b 0.45
I
V
Gain Control Non-linearity, VIN e g 0.5V
1.5
4
I
%
NL, AV e 1
AV e 0.5
AV e 0.25
Signal Non-linearity, VIN e 0 to g 1V, VGAIN e 0.55V
Signal Non-linearity, VIN e 0 to g 1V, VGAIN e 0V
Signal Non-linearity, VIN e 0 to g 1V, VGAIN e b0.25V
0.01
0.05
0.2
0.5
V
V
I
%
%
%
RGAIN
Resistance between VGAIN and VGAIN
4.6
5.5
6.6
I
kX
IS
Supply Current
12
14.5
19
I
mA
FT
Off-Channel Feedthrough
b 75
b 50
I
dB
2
TD is 3.3in
VS e g 5V, TA e 25§ C, VGAIN e a 0.6V to measure channel A, VGAIN e b0.6V to measure channel B, VGAIN e 0V, unless
otherwise specified
EL4094C
Video Gain Control/Fader
Closed Loop AC Electrical Characteristics
Parameter
Limits
Description
Min
Typ
Max
Test
Level
Units
SR
Slew Rate; VOUT from b3V to a 3V measured at b2V and a 2V
370
500
V
V/ms
BW
Bandwidth, b3 dB
b 1 dB
b 0.1 dB
45
60
35
6
III
V
V
MHz
MHz
MHz
dG
Differential Gain, AC amplitude of 286 mVp-p
at 3.58 MHz on DC offset of b0.7, 0, and a 0.7V AV e 100%
AV e 50%
AV e 25%
0.02
0.20
0.40
V
V
V
%
%
%
Differential Phase, AC ampitude of 286 mVp-p
at 3.58 MHz on DC offset of b0.7, 0, and a 0.7V AV e 100%
AV e 50%
AV e 25%
0.04
0.20
0.20
V
V
V
(§ )
(§ )
(§ )
di
BW, GAIN
b 3 dB Gain Control Bandwidth, VGAIN Amplitude 0.5 Vp-p
20
V
MHz
TREC, GAIN
Gain Control Recovery from Overload; VGAIN from b0.6V to 0V
70
V
ns
Typical Performance Curves
Small-Signal Step
Response for Gain e 100%, 50%,
25%, and 0%. VS g 5V
Large-Signal Step
Response for Gain e 100%, 50%,
25%, and 0%. VS g 12V
4094 – 2
4094 – 3
3
TD is 2.6in
VS e g 15V, CL e 15 pF, TA e 25§ C, AV e 100% unless otherwise noted
EL4094C
Video Gain Control/Fader
Typical Performance Curves Ð Contd.
Frequency Response vs
Capacitive Loading
Frequency Response vs
Resistive Loading
Frequency Response vs Gain
Off-Channel Isolation
Over Frequency
Change in Slewrate and
Bandwidth with Supply Voltage
Output Noise Over Frequency
4094 – 4
4
EL4094C
Video Gain Control/Fader
Typical Performance Curves Ð Contd.
Change in 100% Gain Error,
Supply Current, Slewrate and
Bandwidth over Temperature
Nonlinearity vs VIN for
Gain e 100%, 75%, 50% and 25%
Differential Gain Error vs
Voffset for Gain e 100%,
75%, 50% and 25%. F e 3.58 MHz
Differential Phase Error vs
Voffset for Gain e 100%,
75%, 50% and 25%. F e 3.58 MHz
Differential Gain Error vs
Voffset for Gain e 100%,
75%, 50% and 25%. F e 3.58 MHz
Differential Phase Error vs
Voffset for Gain e 100%,
75%, 50% and 25%. F e 3.58 MHz
4094 – 5
5
EL4094C
Video Gain Control/Fader
Typical Performance Curves Ð Contd.
Differential Gain and
Phase Error vs Gain
Differential Gain and
Phase Error vs Gain
4094 – 6
Gain vs VG. 1VDC at VINA
Cross-Fade Balance. VINA e VINB e 0V
4094 – 7
4094 – 8
Gain Control Response to
a Non-Overloading Step,
Constant Sinewave at VINA
VGAIN Overload Recovery Response
4094 – 10
4094 – 9
6
EL4094C
Video Gain Control/Fader
Typical Performance Curves Ð Contd.
Gain Control Gain vs Frequency
Change in V(100%) and V(0%) of
Gain Control vs /VG Offset
Change in V(100%) and V(0%) of Gain
Control vs Supply Voltage
Change in V(100%) and V(0%) of Gain
Control vs Die Temperature
Supply Current vs Supply Voltage
Maximum Dissipation vs
Ambient Temperature
4094 – 11
7
EL4094C
Video Gain Control/Fader
it is necessary to overdrive the gain control input
by 30 mV or more. This would set the gain control voltage range as b 0.565V to a 0.565V, or
30 mV beyond the maximum guaranteed 0% to
100% range. In fact, the gain control inputs are
very complex. Here is a representation of the terminals:
Applications Information
The EL4094 is a self-contained and calibrated
fader subsystem. When a given channel has
100% gain the circuit behaves as a current-feedback amplifier in unity-gain connection. As such,
video and transfer distortions are very low. As
the gain of the input is reduced, a 2-quadrant
multiplier is gradually introduced into the signal
path and distortions increase with reducing gain.
The input impedance also changes with gain setting, from about 1 MX at 100% gain down to
16 kX at zero gain. To maximize gain accuracy
and linearity, the inputs should be driven from
source impedances of 500X or less.
Linearity
4094 – 12
Representation of Gain Control
Inputs VG and /VG
The EL4094 is designed to work linearly with
g 2V inputs, but lowest distortion occurs at g 1V
levels and below. Errors are closer to those of a
good current-feedback amplifier above 90% gain.
For gain control inputs between g 0.5V
( g 90 mA), the diode bridge is a low impedance
and all of the current into Vg flows back out
through/Vg. When gain control inputs exceed
this amount, the bridge becomes a high impedance as some of the diodes shut off, and the Vg
impedance rises sharply from the nominal 5.5KX
to about 500KX. This is the condition of gain
control overdrive. The actual circuit produces a
much sharper overdrive characteristic than does
the simple diode bridge of this representation.
Low-frequency linearity is 0.1% or better for
gains 25% to 100% and inputs up to 1V. NTSC
differential gain and phase errors are better than
0.3% and 0.3§ for the 25% to 100% gain range.
These distortions are not strongly affected by
supply voltage nor output loading, at least down
to 150X. For settling to 0.1%, however, it is best
to not load the output heavily and to run the
EL4094 on the lowest practical supply voltages,
so that thermal effects are minimized.
The gain input has a 20 MHz b 3 dB bandwidth
and 17 ns risetime for inputs to g 0.45V. When
the gain control voltage exceeds the 0% or 100%
values, a 70 ns overdrive recovery transient will
occur when it is brought back to linear range. If
quicker gain overdrive response is required, the
Force control inputs of the EL4095 can be used.
Gain Control Inputs
The gain control inputs are differential and may
be biased at any voltage as long as /VGAIN is less
than 2.5V below V a and 3V above V b . The differential input impedance is 5.5 kX, and the common-mode impedance is more than 500 kX. With
zero differential voltage on the gain inputs, both
signal inputs have a 50% gain factor. Nominal
calibration sets the 100% gain of VINA input at
a 0.5V of gain control voltage, and 0% at b 0.5V
of gain control. VINB’s gain is complementary to
that of VINA; a 0.5V of gain control sets 0% gain
at VINB and b 0.5V gain control sets 100% VINB
gain. The gain control does not have a completely abrupt transition at the 0% and 100% points.
There is about 10 mV of ‘‘soft’’ transfer at the
gain endpoints. To obtain the most accurate
100% gain factor or best attenuation at 0% gain,
Output Loading
The EL4094 does not work well with heavy capacitive loads. Like all amplifier outputs, the output impedance becomes inductive over frequency
resonating with a capacitive load. The effective
output inductance of the EL4094 is about 350
nH. More than 50 pF will cause excessive frequency response peaking and transient ringing.
The problem can be solved by inserting a lowvalue resistor in series with the load, 22X or
more. If a series resistance cannot be used, then
adding a 300X or less load resistor to ground or a
‘‘snubber’’ network may help. A snubber is a re8
EL4094C
Video Gain Control/Fader
perature. The EL4094 thus cannot be operated
with g 15V supplies at 75§ C in the surface-mount
package; the supplies should be reduced to g 5V
to g 12V levels, especially if extra dissipation occurs when driving a load.
Applications Information Ð Contd.
sistor in series with a capacitor, 150X and 100 pF
being typical values. The advantage of a snubber
is that it does not draw DC load current.
Unterminated coaxial line loads can also cause
resonances, and they should be terminated either
at the far end or a series back-match resistor installed between the EL4094 and the cable.
The EL4094 as a Level Adjust
A common use for gain controls is as an input
signal levellerÐa circuit that scales too-large or
too-small signals to a standard amplitude. A typical situation would be to scale a variable video
input by a 6 dB to b 6 dB to obtain a standard
amplitude. The EL4094 cannot provide more
than 0 dB gain, but it can span the range of 0 dB
to b 12 dB with another amplifier gaining the
output up by 6 dB. The simplest way to obtain
the range is to simply ground the B input and
vary the gain of the signal applied to the A input.
The disadvantage of this approach is that linearity degrades at low gains. By connecting the signal to the A input of the EL4094 and the signal
attenuated by 12 dB to the B input, the gain control offers the highest linearity possible at 0 dB
and b 12 dB extremes, and good performance between. The circuit is shown on the following
page.
The output stage can deliver up to 140 mA into a
short-circuit load, but it is only rated for a continuous 35 mA. More continuous current can
cause reliability problems with the on-chip metal
interconnect. Video levels and loads cause no
problems at all.
Noise
The EL4094 has a very simple noise characteristic: the output noise is constant (40 nV/ SHz
wideband) for all gain settings. The input-referred noise is then the output noise divided by
the gain. For instance, at a gain of 50% the input
noise is 40 nV/ SHz/0.5, or 80 nV/ SHz.
Bypassing
The EL4095 can be used to provide the required
gains without the extra amplifier. In practice, the
gain control is adjusted to set a standard video
level regardless of the input level. The EL4583
sync-separator has a recovered amplitude output
that can be used to servo the gain control voltage. Here is the curve of differential gain and
phase distortion for varying inputs, with the output set to standard video level:
The EL4094 is fairly tolerant of power-supply
bypassing, but best multiplier performance is obtained with closely connected 0.1 mF ceramic capacitors. The leaded chip capacitors are good, but
neither additional tantalums nor chip components are necessary. The signal inputs can oscillate locally when connected to long lines or unterminated cables.
Power Dissipation
Peak die temperature must not exceed 150§ C. At
this temperature, the epoxy begins to soften and
becomes unstable, chemically and mechanically.
This allows 75§ C internal temperature rise for a
75§ C ambient. The EL4094 in the 8-pin PDIP
package has a thermal resistance of 87§ /W, and
can thus dissipate 862 mW at a 75§ C ambient
temperature. The device draws 17 mA maximum
supply current, only 510 mW at g 15V supplies,
and the circuit has no dissipation problems in
this package.
The SO-8 surface-mount package has a 153§ /W
thermal resistance with the EL4094, and only
490 mW can be dissipated at 75§ C ambient tem-
4094 – 14
Differential Gain and Phase of
Linearized Level Control
9
EL4094C
Video Gain Control/Fader
For an adjustable preemphasis filter, for instance,
filter A might be an all-pass filter to compensate
for the delay of filter B, a peaking filter. Fading
the gain from A to B provides a variable amount
of peaking, but constant delay.
Applications Information Ð Contd.
The differential gain error is kept to 0.3% and
the differential phase to 0.15§ or better over the
entire input range.
The EL4094 as an Adjustable Filter
The EL4094 as a Phase Modulator
Equalizers are used to adjust the delay or frequency response of systems. A typical use is to
compensate for the high-frequency loss of a cable
system ahead of the cable so as to create a flat
response at the far end. A generalized scheme
with the EL4094 is shown below.
To make a phase modulator, filter A might be a
leading-phase network, and filter B a lagging network. The wide bandwidth of the gain-control input allows wideband phase modulation of the
carrier applied to the main input. Of course, the
carrier and gain inputs must not be digital but be
reasonably clean sinewaves for the modulation to
be accurate.
4094 – 13
a 6 dB to b 6 dB Linearized Level Control
4094 – 15
General Adjustable Equalizer
10
This macromodel is offered to allow simulation of
general EL4094 behavior. We have included
these characteristics:
Small-signal frequency response
Output loading effects
Input impedance
Off-channel feedthrough
Output impedance over frequency
Signal path DC distortions
VGAIN I-V characteristics
VGAIN overdrive recovery delay
100% gain error
These will give a good range of results for various
operating conditions, but the macromodel does
not behave identically as the circuit in these areas:
Temperature effects
Signal overload effects
Signal and /VG operating range
Current-limit
Video and high-frequency distortions
Supply voltage effects
Slewrate limitations
Noise
Power supply interactions
The macromodel’s netlist is based on the Pspice
simulator (copywritten by the Microsim Company). Other simulators may not support the
POLY function, which is used to implement multiplication as well as square-low nonlinearities.
******
******
*
*
*
*
*
*
.subckt EL4094subckt
***
VINB
l
l
l
l
l
VOUT
l
l
l
l
/VG
l
l
l
VG
l
l
VINA
(1
4
6
7
8)
l
11
TAB WIDE
ROL 810 0 290k
Ccomp 810 0 3.5p
G1 10 0 810 0 b10
ROUT 10 0 0.1
LOUT 10 4 350.200n
RLOUT 10 4 80
r1 10 910 10
c1 910 911 300p
r2 911 0 90
***
*** Input channel A
***
RINA 22 910 16k
ra 11 0 1k
Cfeedthrougha 23 8 130p
Rfeedthrougha 8 22 1.0
Ela 23 22 1 0 1.0
Rspice3 23 22 1E12
G1a 11 0 POLY(1) (22, 910) 0.0 0.001 b3Eb6
G2a 810 0 POLY(2) (11,0) (13, 0) 0.0 0.0 0.0 0.0 0.001
***
***Input channel B
***
RINB 25 910 16k
rb 20 0 1k
Cfeedthroughb 24 1 130p
Rfeedthroughb 1 25 1.0
E1b 24 25 8 0 1.0
Rspice4 24 25 1E12
G1b 20 0 POLY(1) (25, 910) 0.0 0.001 b3Eb6
G2b 810 0 POLY(2) (20,0) (19, 0) 0.0 0.0 0.0 0.0 0.001
***
***Gain control
***
Rspice1 13 0 1E12
Rspice2 18 0 1E12
R10 14 0 1E7
C10 14 0 8Eb16
D1 14 15 Dclamp
D2 16 14 Dclamp
.model Dclamp D (TT e 200n)
V1 15 0 4999.3
V2 0 16 4999.3
V3 13 17 0.5
V4 19 18 0.5
G10 14 0 7 6 b0.001
G11 7 6 14 0 b2Eb8
E10 17 0 14 0 1Eb4
E11 18 0 14 0 b1Eb4
***
.ends
******
EL4094C Macromodel
TD is 6.8in
TD is 1.3in
Video Gain Control/Fader
TAB WIDE
EL4094C
EL4094C
EL4094C
Video Gain Control/Fader
EL4094C Macromodel Ð Contd.
4094 – 16
EL4094 Macromodel Schematic
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.
August 1996, Rev D
WARNING Ð 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 intended 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 replacement of defective components and does not cover injury to persons or property or other consequential damages.
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
12
Printed in U.S.A.
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