AD818AR-REEL [ADI]
Low Cost, Low Power Video Op Amp; 低成本，低功耗视频运算放大器
| 型号： | AD818AR-REEL |
| 厂家： | 
ADI |
| 描述： | Low Cost, Low Power Video Op Amp |
| 文件： | 总12页 (文件大小：353K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
Low Cost, Low Power
Video Op Amp
a
AD818
CONNECTION DIAGRAMS
8-Lead Plastic Mini-DIP (N), and
SOIC (R) Packages
FEATURES
Low Cost
Excellent Video Performance
55 MHz 0.1 dB Bandwidth (Gain = +2)
0.01% & 0.05؇ Differential Gain & Phase Errors
High Speed
130 MHz Bandwidth (3 dB, G = +2)
100 MHz Bandwidth (3 dB, G+ = –1)
500 V/s Slew Rate
80 ns Settling Time to 0.01% (VO = 10 V Step)
High Output Drive Capability
50 mA Minimum Output Current
Ideal for Driving Back Terminated Cables
Flexible Power Supply
NULL
8
NULL
–IN
1
2
AD818
+V
7
6
S
+IN
OUTPUT
NC
3
4
5
–V
S
TOP VIEW
NC = NO CONNECT
Specified for Single (+5 V) and Dual (؎5 V to ؎15 V)
Power Supplies
Low Power: 7.5 mA max Supply Current
Available in 8-Lead SOIC and 8-Lead Plastic Mini-DIP
and 500 V/µs slew rate make the AD818 useful in many high
speed applications including: video monitors, CATV, color
copiers, image scanners and fax machines.
PRODUCT DESCRIPTION
The AD818 is a low cost, video op amp optimized for use in
video applications which require gains equal to or greater than
+2 or –1. The AD818 low differential gain and phase errors,
single supply functionality, low power and high output drive
make it ideal for cable driving applications such as video cam-
eras and professional video equipment.
The AD818 is fully specified for operation with a single +5 V
power supply and with dual supplies from 5 V to 15 V. This
power supply flexibility, coupled with a very low supply current
of 7.5 mA and excellent ac characteristics under all power
supply conditions, make the AD818 the ideal choice for many
demanding yet power sensitive applications.
With video specs like 0.1 dB flatness to 55 MHz and low differ-
ential gain and phase errors of 0.01% and 0.05°, along with
50 mA of output current, the AD818 is an excellent choice for
any video application. The 130 MHz 3 dB bandwidth (G = +2)
The AD818 is a voltage feedback op amp and excels as a gain
stage in high speed and video systems (gain = >2 or –1). It
achieves a settling time of 45 ns to 0.1%, with a low input offset
voltage of 2 mV max.
The AD818 is available in low cost, small 8-lead plastic mini-
DIP and SOIC packages.
+15V
0.02
0.01µF
2.2µF
DIFF GAIN
0.01
7
V
Rbt
75Ω
IN
3
2
75
Ω
6
AD818
0.06
0.05
0.00
4
Rt
75
Ω
DIFF PHASE
0.1µF
2.2µF
0.04
0.03
–15V
1kΩ
5
10
15
1k
Ω
SUPPLY VOLTAGE – Vꢀols
AD818 Video Line Driver
AD818 Differential Gain and Phase vs. Supply
REV. B
Information furnished by Analog Devices is believed to be accurate and
reliable. However, no responsibility is assumed by Analog Devices 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 Analog Devices.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781/329-4700
Fax: 781/326-8703
World Wide Web Site: http://www.analog.com
© Analog Devices, Inc., 2000
(@ TA = +25؇C, unless otherwise noted)
AD818–SPECIFICATIONS
AD818A
Typ
Parameter
Conditions
VS
Min
Max
Units
DYNAMIC PERFORMANCE
–3 dB Bandwidth
Gain = +2
5 V
70
100
40
50
70
30
20
40
10
18
40
10
95
130
55
70
100
50
43
55
18
34
72
19
MHz
MHz
MHz
MHz
MHz
MHz
MHz
MHz
MHz
MHz
MHz
MHz
15 V
0, +5 V
5 V
15 V
0, +5 V
5 V
15 V
0, +5 V
5 V
15 V
0, +5 V
Gain = –1
Bandwidth for 0.1 dB Flatness
Gain = +2
CC = 2 pF
Gain = –1
CC = 2 pF
Full Power Bandwidth1
Slew Rate
VOUT = 5 V p-p
RLOAD = 500 Ω
VOUT = 20 V p-p
RLOAD = 1 kΩ
RLOAD = 1 kΩ
Gain = –1
5 V
25.5
MHz
15 V
5 V
15 V
0, +5 V
5 V
15 V
5 V
8.0
MHz
V/µs
V/µs
V/µs
ns
ns
ns
350
450
250
400
500
300
45
45
80
Settling Time to 0.1%
to 0.01%
–2.5 V to +2.5 V
0 V–10 V Step, AV = –1
–2.5 V to +2.5 V
0 V–10 V Step, AV = –1
15 V
15 V
15 V
5 V
0, +5 V
15 V
5 V
80
63
ns
dB
%
%
Total Harmonic Distortion
Differential Gain Error
(RL = 150 Ω)
F
C = 1 MHz
NTSC
Gain = +2
0.005
0.01
0.08
0.045
0.06
0.1
0.01
0.02
%
Differential Phase Error
(RL = 150 Ω)
NTSC
Gain = +2
0.09
0.09
Degrees
Degrees
Degrees
pF
0, +5 V
Cap Load Drive
10
INPUT OFFSET VOLTAGE
5 V to 15 V
5 V, 15 V
5 V, 15 V
5 V
0.5
2
3
mV
mV
µV/°C
T
MIN to TMAX
Offset Drift
10
INPUT BIAS CURRENT
3.3
6.6
10
4.4
nA
nA
nA/°C
TMIN
TMAX
INPUT OFFSET CURRENT
25
300
500
nA
nA
nA/°C
TMIN to TMAX
Offset Current Drift
OPEN-LOOP GAIN
0.3
VOUT
= 2.5 V
RLOAD = 500 Ω
TMIN to TMAX
RLOAD = 150 Ω
3
2
2
5
4
9
V/mV
V/mV
V/mV
VOUT
=
10 V
15 V
15 V
RLOAD = 1 kΩ
TMIN to TMAX
6
3
V/mV
V/mV
VOUT
= 7.5 V
RLOAD = 150 Ω
(50 mA Output)
3
5
V/mV
COMMON-MODE REJECTION
POWER SUPPLY REJECTION
VCM
VCM
TMIN to TMAX
=
=
2.5 V
12 V
5 V
15 V
15 V
82
86
84
100
120
100
dB
dB
dB
VS = 5 V to 15 V
TMIN to TMAX
80
80
90
dB
dB
INPUT VOLTAGE NOISE
INPUT CURRENT NOISE
f = 10 kHz
f = 10 kHz
5 V, 15 V
5 V, 15 V
10
nV/√Hz
pA/√Hz
1.5
–2–
REV. B
AD818
AD818A
Typ
Parameter
Conditions
VS
Min
Max
Units
INPUT COMMON-MODE VOLTAGE
RANGE
5 V
+3.8
–2.7
+13
–12
+3.8
+1.2
+4.3
–3.4
+14.3
–13.4
+4.3
+0.9
V
V
V
V
V
V
15 V
0, +5 V
OUTPUT VOLTAGE SWING
Output Current
R
LOAD = 500 Ω
5 V
5 V
15 V
15 V
0, +5 V
3.3
3.2
13.3
12.8
+1.5,
+3.5
50
3.8
3.6
13.7
13.4
V
V
V
V
RLOAD = 150 Ω
R
RLOAD = 500 Ω
RLOAD = 500 Ω
LOAD = 1 kΩ
V
15 V
5 V
0, +5 V
15 V
mA
mA
mA
mA
50
30
Short-Circuit Current
INPUT RESISTANCE
INPUT CAPACITANCE
OUTPUT RESISTANCE
90
300
1.5
8
kΩ
pF
Ω
Open Loop
POWER SUPPLY
Operating Range
Dual Supply
Single Supply
2.5
+5
18
+36
7.5
7.5
7.5
7.5
V
V
mA
mA
mA
mA
Quiescent Current
5 V
5 V
15 V
15 V
7.0
7.0
TMIN to TMAX
TMIN to TMAX
NOTE
1Full power bandwidth = slew rate/2 π VPEAK
.
2.0
1.5
1.0
0.5
0
Specifications subject to change without notice.
T
J
= 150°C
8-LEAD MINI-DIP PACKAGE
ABSOLUTE MAXIMUM RATINGS1
Supply Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 V
Internal Power Dissipation2
Plastic (N) . . . . . . . . . . . . . . . . . . . . . . See Derating Curves
Small Outline (R) . . . . . . . . . . . . . . . . . See Derating Curves
Input Voltage (Common Mode) . . . . . . . . . . . . . . . . . . . . VS
Differential Input Voltage . . . . . . . . . . . . . . . . . . . . . . . . 6 V
Output Short Circuit Duration . . . . . . . . See Derating Curves
Storage Temperature Range (N, R) . . . . . . . –65°C to +125°C
Operating Temperature Range . . . . . . . . . . . –40°C to +85°C
8-LEAD SOIC PACKAGE
Lead Temperature Range (Soldering 10 seconds) . . . . +300°C
NOTES
–50 –40 –30 –20 –10
0 +10 +20 +30 +40 +50 +60 +70 +80 +90
1Stresses above those listed under Absolute Maximum Ratings may cause perma-
nent damage to the device. This is a stress rating only; functional operation of the
device at these or any other conditions above those indicated in the operational
section of this specification is not implied. Exposure to absolute maximum rating
conditions for extended periods may affect device reliability.
2Specification is for device in free air: 8-lead plastic package, θJA = 90°C/W; 8-lead
SOIC package, θJA = 155°C/W.
AMBIENT TEMPERATURE – °C
Maximum Power Dissipation vs. Temperature for Differ-
ent Package Types
ESD SUSCEPTIBILITY
ORDERING GUIDE
ESD (electrostatic discharge) sensitive device. Electrostatic
charges as high as 4000 volts, which readily accumulate on the
human body and on test equipment, can discharge without de-
tection. Although the AD818 features proprietary ESD protec-
tion circuitry, permanent damage may still occur on these
devices if they are subjected to high energy electrostatic dis-
charges. Therefore, proper ESD precautions are recommended
to avoid any performance degradation or loss of functionality.
Temperature
Range
Package
Description
Package
Option
Model
AD818AN
–40°C to +85°C
–40°C to +85°C
8-Lead
Plastic DIP
8-Lead
N-8
AD818AR
SO-8
Plastic SOIC
13" Tape & Reel
7" Tape & Reel
AD818AR-REEL –40°C to +85°C
AD818AR-REEL7 –40°C to +85°C
SO-8
SO-8
REV. B
–3–
AD818 –Typical Characteristics
METALIZATION PHOTOGRAPH
Dimensions shown in inches and (mm).
600
500
20
15
10
+V
CM
400
300
200
–V
CM
5
0
0
5
10
SUPPLY VOLTAGE – Vꢀols
15
20
0
15
SUPPLY VOLTAGE – Vꢀols
20
5
10
Figure 3. Slew Rate vs. Supply Voltage
Figure 1. Common-Mode Voltage Range vs. Supply
30
20
15
10
5
25
V
= 15V
S
20
15
10
5
R
= 500Ω
L
Ω
= 150
R
L
V
= 5V
S
0
0
10
100
1k
10k
5
10
15
20
0
SUPPLY VOLTAGE – Vꢀols
LOAD RESISTANCE – Ω
Figure 2. Output Voltage Swing vs. Load Resistance
Figure 4. Output Voltage Swing vs. Supply
–4–
REV. B
AD818
70
60
50
95
8.0
7.5
7.0
PHASE MARGIN
85
75
+85°C
+25°C
-40°C
GAIN/BANDWIDTH
40
30
65
6.5
6.0
55
–60 –40 –20
0
20
40
60
80
100 120 140
5
10
SUPPLY VOLTAGE – Vꢀols
15
20
0
TEMPERATURE – °C
Figure 8. –3 dB Bandwidth and Phase Margin vs.
Temperature. Gain = +2
Figure 5. Quiescent Supply Current vs. Supply Voltage
9
100
15V
8
10
1
7
5V
6
5
0.1
4
3
0.01
100
1k
10k
1k
10k
100k
1M
10M
100M
FREQUENCY – Hz
LOAD RESISTANCE – Ohms
Figure 9. Open-Loop Gain vs. Load Resistance
Figure 6. Closed-Loop Output Impedance vs. Frequency
130
7
6
5
110
SOURCE CURRENT
90
4
3
2
SINK CURRENT
70
50
30
1
–60 –40 –20
0
–60 –40 –20
20
40
60
80
100 120 140
20
40
60
80
100 120 140
0
TEMPERATURE –
°C
TEMPERATURE – °C
Figure 7. Input Bias Current vs. Temperature
Figure 10. Short Circuit Current vs. Temperature
REV. B
–5–
AD818–Typical Characteristics
10
8
100
+100
+80
PHASE 5V OR
15V SUPPLIES
80
6
4
15V SUPPLIES
= 1k
60
40
20
0
+60
+40
+20
0
R
Ω
1%
1%
0.1%
0.1%
L
0.01%
0.01%
2
0
–2
–4
5V SUPPLIES
= 1k Ω
R
L
–6
–8
–10
–20
20
40
60
80
100
120
140
160
0
1k
10k
100k
1M
10M
100M
1G
SETTLING TIME – ns
FREQUENCY – Hz
Figure 11. Open-Loop Gain and Phase Margin vs.
Frequency
Figure 14. Output Swing and Error vs. Settling Time
50
40
100
90
80
+SUPPLY
70
30
20
60
50
–SUPPLY
40
10
0
30
20
10
1
10
100
1k
10k
100k
1M
10M
100
1k
10k
100k
1M
10M
100M
FREQUENCY – Hz
FREQUENCY – Hz
Figure 12. Power Supply Rejection vs. Frequency
Figure 15. Input Voltage Noise Spectral Density vs.
Frequency
120
30
R = 1k
Ω
L
100
80
20
10
R = 150Ω
L
60
40
0
100k
1k
10k
100k
1M
10M
1M
10M
100M
FREQUENCY – Hz
FREQUENCY – Hz
Figure 16. Output Voltage vs. Frequency
Figure 13. Common-Mode Rejection vs. Frequency
–6–
REV. B
AD818
–40
–50
C
C
10
9
8
7
6
5
4
3
2
1
V
C
0.1dB
Foalness
S
C
R
= 150Ω
L
1k
AD818
1k
IN
2V p-p
V
OUT
؎15V 2pF 55 MHz
؎5V 1pF 43 MHz
+5V 1pF 18 MHz
V
150
–60
–70
2nd HARMONIC
؎15V
؎5V
–80
–90
3rd HARMONIC
+5V
–100
100
1k
10k
100k
1M
10M
1M
10M
100M
1G
FREQUENCY – Hz
FREQUENCY – Hz
Figure 20. Closed-Loop Gain vs. Frequency (G = +2)
Figure 17. Harmonic Distortion vs. Frequency
650
10
2pF
V
0.1dB
8
6
4
2
0
S
FLATNESS
1k
1k
15V 72 MHz
5V 34 MHz
V
OUT
550
450
350
250
V
AD818
IN
+5V 19 MHz
150
15V
–2
–4
–6
+5V
5V
–8
–10
–60 –40 –20
20
40
60
80
100 120 140
0
1G
1M
10M
100M
TEMPERATURE – °C
FREQUENCY – Hz
Figure 18. Slew Rate vs. Temperature
Figure 21. Closed-Loop Gain vs. Frequency (G = –1)
0.02
0.01
DIFF GAIN
0.00
0.06
0.05
0.04
DIFF PHASE
0.03
5
10
15
SUPPLY VOLTAGE – Vꢀols
Figure 19. Differential Gain and Phase vs. Supply Voltage
REV. B
–7–
AD818–Typical Characteristics
C
F
1k
S
Ω
5V
50ns
+V
3.3µF
100
90
0.01µF
HP
V
1kΩ
IN
PULSE (LS)
OR FUNCTION
(SS)
7
2
3
TEKTRONIX
7A24
PREAMP
TEKTRONIX
P6201 FET
PROBE
6
GENERATOR
AD818
50
Ω
V
OUT
10
4
0.01µF
0%
R
5V
L
3.3µF
–V
S
Figure 22. Inverting Amplifier Connection
Figure 25. Inverter Large Signal Pulse Response 15 VS,
CF = 1 pF, RL = 1 kΩ
2V
50ns
200mV
10ns
100
90
100
90
10
10
0%
0%
200mV
2V
Figure 26. Inverter Small Signal Pulse Response 15 VS,
Figure 23. Inverter Large Signal Pulse Response 5 VS,
CF = 1 pF, RL = 150 Ω
CF = 1 pF, RL = 1 kΩ
200mV
200mV
10ns
10ns
100
90
100
90
10
10
0%
0%
200mV
200mV
Figure 24. Inverter Small Signal Pulse Response 5 VS,
Figure 27. Inverter Small Signal Pulse Response 5 VS,
CF = 1 pF, RL = 150 Ω
CF = 0 pF, RL = 150 Ω
–8–
REV. B
AD818
C
F
1k
Ω
1k
S
Ω
5V
50ns
3.3µF
+V
100
90
0.01µF
7
2
3
TEKTRONIX
P6201 FET
PROBE
TEKTRONIX
7A24
PREAMP
6
HP
AD818
V
Ω
100
PULSE (LS)
OR FUNCTION
(SS)
IN
V
OUT
4
10
0.01µF
GENERATOR
0%
Ω
50
R
L
5V
3.3µF
–V
S
Figure 28. Noninverting Amplifier Connection
Figure 31. Noninverting Large Signal Pulse Response
15 V, CF = 1 pF, RL = 1 kΩ
2V
50ns
100mV
10ns
100
90
100
90
10
10
0%
0%
200mV
2V
Figure 29. Noninverting Large Signal Pulse Response
Figure 32. Noninverting Small Signal Pulse Response
5 V, CF = 1 pF, RL = 1 kΩ
15 V, CF = 1 pF, RL = 150 Ω
100mV
10ns
100mV
10ns
100
90
100
90
10
10
0%
0%
200mV
200mV
Figure 30. Noninverting Small Signal Pulse Response
Figure 33. Noninverting Small Signal Pulse Response
5 V, CF = 1 pF, RL = 150 Ω
5 V, CF = 0 pF, RL = 150 Ω
REV. B
–9–
AD818
+V
may result in peaking. A small capacitance (1–5 pF) may be
used in parallel with the feedback resistor to neutralize this
effect.
S
Power supply leads should be bypassed to ground as close as
possible to the amplifier pins. Ceramic disc capacitors of
0.1 µF are recommended.
OUTPUT
–IN
+V
S
7
2
3
+IN
AD818
6
8
1
4
10k⍀
–V
S
V
ADJUST
OS
–V
S
NULL 1
NULL 8
Figure 35. Offset Null Configuration
OFFSET NULLING
Figure 34. AD818 Simplified Schematic
THEORY OF OPERATION
The input offset voltage of the AD818 is inherently very low.
However, if additional nulling is required, the circuit shown in
Figure 35 can be used. The null range of the AD818 in this
configuration is 10 mV.
The AD818 is a low cost, video operational amplifier designed
to excel in high performance, high output current video
applications.
The AD818 (Figure 34) consists of a degenerated NPN differ-
ential pair driving matched PNPs in a folded-cascode gain stage.
The output buffer stage employs emitter followers in a class AB
amplifier which delivers the necessary current to the load, while
maintaining low levels of distortion.
SINGLE SUPPLY OPERATION
Another exciting feature of the AD818 is its ability to perform
well in a single supply configuration. The AD818 is ideally
suited for applications that require low power dissipation and
high output current.
The AD818 will drive terminated cables and capacitive loads of
10 pF or less. As the closed-loop gain is increased, the AD818
will drive heavier cap loads without oscillating.
Referring to Figure 36, careful consideration should be given to
the proper selection of component values. The choices for
this particular circuit are: R1 + R3ʈR2 combine with C1 to
form a low frequency corner of approximately 10 kHz. C4 was
inserted in series with R4 to maintain amplifier stability at high
frequency.
INPUT CONSIDERATIONS
An input protection resistor (RIN in Figure 28) is required in
circuits where the input to the AD818 will be subjected to tran-
sient of continuous overload voltages exceeding the 6 V maxi-
mum differential limit. This resistor provides protection for the
input transistors by limiting their maximum base current.
Combining R3 with C2 forms a low pass filter with a corner
frequency of approximately 500 Hz. This is needed to maintain
amplifier PSRR, since the supply is connected to VIN through
the input divider. The values for R2 and C2 were chosen to
demonstrate the AD818’s exceptional output drive capability. In
this configuration, the output is centered around 2.5 V. In order
to eliminate the static dc current associated with this level, C3
was inserted in series with RL.
For high performance circuits, it is recommended that a “bal-
ancing” resistor be used to reduce the offset errors caused by
bias current flowing through the input and feedback resistors.
The balancing resistor equals the parallel combination of RIN
and RF and thus provides a matched impedance at each input
terminal. The offset voltage error will then be reduced by more
than an order of magnitude.
+V
S
R3
100⍀
GROUNDING AND BYPASSING
SELECT C1, R1, R2
R4
1k⍀
When designing high frequency circuits, some special precau-
tions are in order. Circuits must be built with short interconnect
leads. When wiring components, care should be taken to pro-
vide a low resistance, low inductance path to ground. Sockets
should be avoided, since their increased interlead capacitance
can degrade circuit bandwidth.
FOR DESIRED LOW
1k⍀
3.3F
FREQUENCY CORNER.
C2
C4
0.001F
3.3F
0.01F
R1
7
2
3
3.3k⍀
C1
0.01F
V
6
AD818
OUT
R
L
V
IN
4
Feedback resistors should be of low enough value (≤1 kΩ) to
assure that the time constant formed with the inherent stray
capacitance at the amplifier’s summing junction will not limit
performance. This parasitic capacitance, along with the parallel
resistance of RF/RIN, form a pole in the loop transmission which
150⍀
R2
3.3k⍀
C3
0.1F
Figure 36. Single Supply Amplifier Configuration
–10–
REV. B
AD818
15pF
Ω
1M
2×
ERROR AMPLIFIER
ERROR
HP2835
V
OUTPUT × 10
5
AD829
7
3
2
SHORT, DIRECT
CONNECTION TO
TEKTRONIX TYPE 11402
OSCILLOSCOPE PREAMP
INPUT SECTION
Ω
100
2×
ERROR
SIGNAL
OUTPUT
6
HP2835
4
0.47µF
0.01µF
0.01µF
0 TO 10V
POWER
SUPPLY
0.47µF
EI&S
–V
S
DL1A05GM
MERCURY
RELAY
FALSE
SUMMING
NODE
+V
NULL
ADJUST
S
1.9k
Ω
7, 8
1kΩ
100Ω
1kΩ
100Ω
500Ω
2
SETTLING
OUTPUT
NOTE:
USE CIRCUIT BOARD
WITH GROUND PLANE
Ω
50
13
TTL LEVEL
SIGNAL
COAX
CABLE
5–18pF
DEVICE
UNDER
TEST
1, 14
GENERATOR
50Hz
500Ω
50Ω
TEKTRONIX P6201
2
FET PROBE TO
OUTPUT
AD818
TEKTRONIX TYPE 11402
OSCILLOSCOPE
6
10pF
4
3
PREAMP INPUT SECTION
SCOPE PROBE
CAPACITANCE
DIGITAL
7
GROUND
2.2µF
0.01µF
ANALOG
GROUND
–V
S
2.2µF
0.01µF
+V
S
Figure 37. Settling Time Test Circuit
DIFFERENTIAL LINE RECEIVER
AD818 SETTLING TIME
Settling time is comprised primarily of two regions. The first is
the slew time in which the amplifier is overdriven, where the
output voltage rate of change is at its maximum. The second is
the linear time period required for the amplifier to settle to
within a specified percent of the final value.
The differential receiver circuit of Figure 39 is useful for many
applications from audio to video. It allows extraction of a low
level signal in the presence of common-mode noise. As shown
in Figure 40, the AD818 provides this function with only
10 nV/√Hz noise at the output.
Measuring the rapid settling time of AD818 (45 ns to 0.1% and
80 ns to 0.01%—10 V step) requires applying an input pulse
with a very fast edge and an extremely flat top. With the AD818
configured in a gain of –1, a clamped false summing junction
responds when the output error is within the sum of two diode
voltages (approximately 1 volt). The signal is then amplified 20
times by a clamped amplifier whose output is connected directly
to a sampling oscilloscope.
2pF
1k⍀
1k⍀
+5V
2.2F
2.2F
0.01F
7
2
DIFFERENTIAL
AD818
OUTPUT
6
0.01F
1k⍀
V
INPUT
OUT
3
4
A High Performance Video Line Driver
The buffer circuit shown in Figure 38 will drive a back-termi-
nated 75 Ω video line to standard video levels (1 V p-p) with
0.1 dB gain flatness to 55 MHz with only 0.05° and 0.01%
differential phase and gain at the 3.58 MHz NTSC subcarrier
frequency. This level of performance, which meets the require-
ments for high-definition video displays and test equipment, is
achieved using only 7 mA quiescent current.
–5V
1k⍀
2pF
Figure 39. Differential Line Receiver
+15V
100
90
2.2µF
0.01µF
20ns
1V
2V
7
Rbl
V
75
Ω
2
IN
Ω
75
AD818
Rl
6
Ω
75
Rl
75Ω
3
4
2.2µF
0.01µF
–15V
1kΩ
10
Ω
0%
1k
Figure 38. Video Line Driver
Figure 40. Performance of Line Receiver, RL = 150 Ω,
G = +2
REV. B
–11–
AD818
A HIGH SPEED, THREE OP AMP IN AMP
OUTLINE DIMENSIONS
Dimensions shown in inches and (mm).
The circuit of Figure 41 uses three high speed op amps: two
AD818s and an AD817. This high speed circuit lends itself well
to CCD imaging and other video speed applications. It has the
optional flexibility of both dc and ac trims for common-mode
rejection, plus the ability to adjust for minimum settling time.
8-Lead Plastic Mini-DIP (N) Package
8
5
0.25
(6.35)
0.31
(7.87)
PIN 1
EACH
AMPLIFIER
1
4
PIN 7
+15V
10µF
+V
EACH
S
AMPLIFIER
0.30 (7.62)
REF
1µF
1µF
0.1µF
0.39 (9.91) MAX
0.1µF
0.035 0.01
(0.89 0.25)
COMMON
0.165 0.01
(4.19 0.25)
0.1µF
10µF
0.1µF
PIN 4
0.011 0.003
(0.28 0.08)
0.18 0.03
(4.57 0.76)
–15V
–V
0.125
(3.18)
MIN
EACH
S
AMPLIFIER
15°
0°
0.018 0.003
(0.46 0.08) (2.54)
0.10
0.033
(0.84)
NOM
–V
IN
SEATING
PLANE
SETTLING
A1
AD818
TIME A.C.
BSC
2-8 pF
CMR ADJUST
1k⍀
8-Lead SOIC (R) Package
1k⍀
1k⍀
0.1968 (5.00)
0.1890 (4.80)
V
OUT
5pF
5pF
A3
AD817
R
2pF
G
1k⍀
8
1
5
4
R
2k⍀
L
0.2440 (6.20)
0.2284 (5.80)
0.1574 (4.00)
0.1497 (3.80)
3pF
1k⍀
970⍀
PIN 1
0.0196 (0.50)
0.0099 (0.25)
0.0500 (1.27)
BSC
A2
؋
45؇ 50⍀
D.C. CMR
ADJUST
AD818
0.0688 (1.75)
0.0532 (1.35)
+V
IN
0.0098 (0.25)
0.0040 (0.10)
SEATING
PLANE
8؇
0؇
0.0500 (1.27)
0.0160 (0.41)
0.0192 (0.49)
0.0138 (0.35)
0.0098 (0.25)
0.0075 (0.19)
BANDWIDTH, SETTLING TIME, & TOTAL HARMONIC DISTORTION VS. GAIN
SMALL
SETTLING THD + NOISE
CADJ
(pF)
SIGNAL
TIME
BELOW INPUT LEVEL
GAIN
R
BANDWIDTH
TO 0.1%
@ 10kHz
G
200ns
370ns
2.5µs
3
10
100
1k⍀ 2-8
222⍀ 2-8
20⍀ 2-8
14.7 MHz
4.5 MHz
960 kHz
82 dB
81 dB
71 dB
Figure 41. High Speed 3 Op Amp In Amp
–12–
REV. B
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