Datasheet AD818AR-REEL, AD818AR, AD818AN, AD818AR-REEL7 Datasheet (Analog Devices)

Low Cost, Low Power

Ω

a

FEATURES
Low Cost
Excellent Video Performance

55 MHz 0.1 dB Bandwidth (Gain = +2)

0.01% & 0.05ⴗ 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% (V

High Output Drive Capability

50 mA Minimum Output Current
Ideal for Driving Back Terminated Cables

Flexible Power Supply

Specified for Single (+5 V) and Dual (ⴞ5 V to ⴞ15 V)
Power Supplies
Low Power: 7.5 mA max Supply Current

Available in 8-Lead SOIC and 8-Lead Plastic Mini-DIP

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 cam­eras and professional video equipment.

With video specs like 0.1 dB flatness to 55 MHz and low differ­ential 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)

+15V

0.01µF

V

IN

3

AD818

2

7

6

4

0.1µF

O

2.2µF

2.2µF

= 10 V Step)

Rbt

75

75

Ω

Ω

Rt
75

Video Op Amp

AD818

CONNECTION DIAGRAMS

8-Lead Plastic Mini-DIP (N), and

SOIC (R) Packages

NULL

NULL

1

AD818

–IN

2

+IN

3

–V

4

S

TOP VIEW

NC = NO CONNECT

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.

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.

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 mini­DIP and SOIC packages.

0.06

0.05

DIFF PHASE

8

+V

7

S

OUTPUT

6

5

NC

DIFF GAIN

0.02

0.01

0.00

DIFFERENTIAL GAIN – Percent

1k

Ω

–15V

1k

Ω

AD818 Video Line Driver

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.

0.04

0.03

DIFFERENTIAL PHASE – Degrees

510

SUPPLY VOLTAGE – ±Volts

15

AD818 Differential Gain and Phase vs. Supply

One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: [phone] World Wide Web Site: http://www.analog.com
Fax: [phone] © Analog Devices, Inc., 2000

AD818–SPECIFICATIONS

(@ TA = +25ⴗC, unless otherwise noted)

Parameter Conditions V

S

Min Typ Max Units

DYNAMIC PERFORMANCE

–3 dB Bandwidth Gain = +2 ±5 V 70 95 MHz

±15 V 100 130 MHz
0, +5 V 40 55 MHz

Gain = –1 ±5 V 50 70 MHz

±15 V 70 100 MHz
0, +5 V 30 50 MHz

Bandwidth for 0.1 dB Flatness Gain = +2 ±5 V 20 43 MHz

AD818A

= 2 pF ± 15 V 40 55 MHz

C

C

0, +5 V 10 18 MHz

Gain = –1 ±5 V 18 34 MHz

= 2 pF ± 15 V 40 72 MHz

C

Full Power Bandwidth

1

Slew Rate R

C

V

= 5 V p-p

OUT

= 500 Ω±5 V 25.5 MHz

R

LOAD

V

= 20 V p-p

OUT

= 1 kΩ±15 V 8.0 MHz

R

LOAD

= 1 kΩ±5 V 350 400 V/µs

LOAD

0, +5 V 10 19 MHz

Gain = –1 ±15 V 450 500 V/µs

0, +5 V 250 300 V/µs

Settling Time to 0.1% –2.5 V to +2.5 V ±5 V 45 ns

0 V–10 V Step, A

= –1 ±15 V 45 ns

V

to 0.01% –2.5 V to +2.5 V ±5 V 80 ns

0 V–10 V Step, A

= –1 ±15 V 80 ns

V

Total Harmonic Distortion FC = 1 MHz ±15 V 63 dB
Differential Gain Error NTSC ±15 V 0.005 0.01 %

= 150 Ω) Gain = +2 ±5 V 0.01 0.02 %

(R

L

0, +5 V 0.08 %

Differential Phase Error NTSC ± 15 V 0.045 0.09 Degrees

= 150 Ω) Gain = +2 ±5 V 0.06 0.09 Degrees

(R

L

0, +5 V 0.1 Degrees

Cap Load Drive 10 pF

INPUT OFFSET VOLTAGE ±5 V to ± 15 V 0.5 2 mV

T

MIN

to T

MAX

3mV

Offset Drift 10 µV/°C

INPUT BIAS CURRENT ±5 V, ± 15 V 3.3 6.6 nA

T
T

MIN

MAX

10 nA

4.4 nA/°C

INPUT OFFSET CURRENT ±5 V, ± 15 V 25 300 nA

to T

T

MIN

MAX

500 nA

Offset Current Drift 0.3 nA/°C

OPEN-LOOP GAIN V

= ±2.5 V ±5 V

OUT

= 500 Ω 3 5 V/mV

R

LOAD

to T

T
R
V
R
T
V
R

MIN

LOAD

OUT

LOAD

MIN

OUT

LOAD

MAX

= 150 Ω 2 4 V/mV

= ±10 V ±15 V

= 1 kΩ 6 9 V/mV

to T

MAX

= ±7.5 V ±15 V

= 150 Ω

2 V/mV

3 V/mV

(50 mA Output) 3 5 V/mV

COMMON-MODE REJECTION V

POWER SUPPLY REJECTION V

= ±2.5 V ± 5 V 82 100 dB

CM

= ±12 V ±15 V 86 120 dB

V

CM

T

to T

MIN

S

T

MIN

MAX

= ±5 V to ± 15 V 80 90 dB

to T

MAX

±15 V 84 100 dB

80 dB

INPUT VOLTAGE NOISE f = 10 kHz ± 5 V, ± 15 V 10 nV/√Hz

INPUT CURRENT NOISE f = 10 kHz ± 5 V, ±15 V 1.5 pA/√Hz

–2–

REV. B

AD818A

Parameter Conditions V

S

Min Typ Max Units

INPUT COMMON-MODE VOLTAGE
RANGE ±5 V +3.8 +4.3 V

–2.7 –3.4 V

±15 V +13 +14.3 V

–12 –13.4 V

0, +5 V +3.8 +4.3 V

+1.2 +0.9 V

AD818

OUTPUT VOLTAGE SWING R

= 500 Ω±5 V 3.3 3.8 ±V

LOAD

= 150 Ω±5 V 3.2 3.6 ±V

R

LOAD

R

= 1 kΩ±15 V 13.3 13.7 ± V

LOAD

= 500 Ω±15 V 12.8 13.4 ± V

R

LOAD

= 500 Ω 0, +5 V +1.5,

R

LOAD

+3.5 V

Output Current ±15 V 50 mA

±5 V 50 mA
0, +5 V 30 mA

Short-Circuit Current ±15 V 90 mA

INPUT RESISTANCE 300 kΩ

INPUT CAPACITANCE 1.5 pF

OUTPUT RESISTANCE Open Loop 8 Ω

POWER SUPPLY

Operating Range Dual Supply ±2.5 ± 18 V

Single Supply +5 +36 V

Quiescent Current ±5 V 7.0 7.5 mA

to T

T

MIN

MAX

±5 V 7.5 mA
±15 V 7.5 mA

T

to T

MIN

NOTE

1

Full power bandwidth = slew rate/2 π V

Specifications subject to change without notice.

ABSOLUTE MAXIMUM RATINGS

Supply Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ±18 V

Internal Power Dissipation

2

PEAK

.

1

MAX

±15 V 7.0 7.5 mA

2.0

8-LEAD MINI-DIP PACKAGE

1.5

TJ = 150°C

Plastic (N) . . . . . . . . . . . . . . . . . . . . . . See Derating Curves

Small Outline (R) . . . . . . . . . . . . . . . . . See Derating Curves

Input Voltage (Common Mode) . . . . . . . . . . . . . . . . . . . . ± V

S

1.0

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

Lead Temperature Range (Soldering 10 seconds) . . . . +300°C

NOTES

1

Stresses above those listed under Absolute Maximum Ratings may cause perma­nent 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.

2

Specification is for device in free air: 8-lead plastic package, θJA = 90°C/W; 8-lead
SOIC package, θJA = 155°C/W.

ORDERING GUIDE

Temperature Package Package

Model Range Description Option

AD818AN –40°C to +85°C 8-Lead N-8

Plastic DIP

AD818AR –40°C to +85°C 8-Lead SO-8

Plastic SOIC

Maximum Power Dissipation vs. Temperature for Differ­ent Package Types

ESD SUSCEPTIBILITY

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 de­tection. Although the AD818 features proprietary ESD protec­tion circuitry, permanent damage may still occur on these
devices if they are subjected to high energy electrostatic dis­charges. Therefore, proper ESD precautions are recommended
to avoid any performance degradation or loss of functionality.

0.5

MAXIMUM POWER DISSIPATION – Watts

0

–50 +90

–30

AMBIENT TEMPERATURE – °C

8-LEAD SOIC PACKAGE

+50 +70+30+10–10

AD818AR-REEL –40°C to +85°C 13" Tape & Reel SO-8
AD818AR-REEL7 –40°C to +85°C 7" Tape & Reel SO-8

+80–40 +40 +60+200–20

REV. B

–3–

AD818

0

–Typical Characteristics

METALIZATION PHOTOGRAPH

Dimensions shown in inches and (mm).

20

15

+V

CM

10

–V

CM

5

INPUT COMMON-MODE RANGE – ± Volts

0

020

5

SUPPLY VOLTAGE – ±Volts

10

15

Figure 1. Common-Mode Voltage Range vs. Supply

30

25

20

15

VS = ±15V

600

500

400

SLEW RATE – V/µs

300

200

020

Figure 3. Slew Rate vs. Supply Voltage

20

15

10

5

SUPPLY VOLTAGE – ±Volts

10

RL = 500

15

Ω

10

5

OUTPUT VOLTAGE SWING – Volts p-p

0

10

100

LOAD RESISTANCE – Ω

VS = ±5V

1k

10k

Figure 2. Output Voltage Swing vs. Load Resistance

–4–

Ω

= 150

R

L

5

OUTPUT VOLTAGE SWING – ±Volts

0

0

5

SUPPLY VOLTAGE – ±Volts

10

15

Figure 4. Output Voltage Swing vs. Supply

2

REV. B

AD818

k

130

30

140

90

50

–40

70

–60

110

12010080604020

0

–20

TEMPERATURE – °C

SHORT CIRCUIT CURRENT – mA

SOURCE CURRENT

SINK CURRENT

0

8.0

7.5

QUIESCENT SUPPLY CURRENT – mA

7.0

6.5

6.0

+85°C

-40°C

0

5

SUPPLY VOLTAGE – ±Volts

10

+25°C

15

2

Figure 5. Quiescent Supply Current vs. Supply Voltage

100

10

1

70

PHASE MARGIN

60

50

GAIN/BANDWIDTH

40

PHASE MARGIN – Degrees

30

–60 140

–40

TEMPERATURE – °C

100 120806040200–20

Figure 8. –3 dB Bandwidth and Phase Margin vs.
Temperature. Gain = +2

9

8

7

6

±15V

±5V

95

85

75

–3dB BANDWIDTH – MHz

65

55

5

OPEN-LOOP GAIN – V/mV

0.1

CLOSED-LOOP OUTPUT IMPEDANCE – Ohms

0.01
1k 10k 100M10M1M100k

FREQUENCY – Hz

Figure 6. Closed-Loop Output Impedance vs. Frequency

7

6

5

4

3

INPUT BIAS CURRENT – µA

2

1

–40

–60

Figure 7. Input Bias Current vs. Temperature

0

–20

TEMPERATURE – °C

140

120806040 10020

4

3

100 1k 10

LOAD RESISTANCE – Ohms

Figure 9. Open-Loop Gain vs. Load Resistance

Figure 10. Short Circuit Current vs. Temperature

REV. B

–5–

0

AD818–Typical Characteristics

OPEN-LOOP GAIN – dB

100

–20

80

60

40

20

0

10k

1k

±15V SUPPLIES
R

±5V SUPPLIES

R

= 1k

Ω

L

FREQUENCY – Hz

L

= 1k

Ω

PHASE ±5V OR
±15V SUPPLIES

100M10M1M100k

Figure 11. Open-Loop Gain and Phase Margin vs.
Frequency

100

90

80

70

60

50

PSR – dB

40

30

20

10

–SUPPLY

1k100

+SUPPLY

10M1M100k10k

FREQUENCY – Hz

1G

100M

+100

+80

+60

+40

+20

0

PHASE MARGIN – Degrees

10

8

6

4

1%

1%

0.1%

0.1%

20

2

0

–2

–4

OUTPUT SWING FROM 0 TO ±V

–6

–8

–10

0

0.01%

0.01%

SETTLING TIME – ns

16

140120100806040

Figure 14. Output Swing and Error vs. Settling Time

50

40

30

20

10

INPUT VOLTAGE NOISE – nV/ Hz

0

10

1

FREQUENCY – Hz

10M

1M100k10k1k100

Figure 12. Power Supply Rejection vs. Frequency

120

100

80

CMR – dB

60

40

1k 10M

10k

100k

FREQUENCY – Hz

1M

Figure 13. Common-Mode Rejection vs. Frequency

Figure 15. Input Voltage Noise Spectral Density vs.
Frequency

30

R = 1k

Ω

L

20

R = 150LΩ

10

OUTPUT VOLTAGE – Volts p-p

0
100k 1M 100M10M

FREQUENCY – Hz

Figure 16. Output Voltage vs. Frequency

–6–

REV. B

AD818

10

0

–10

1M 10M 100M

–2

–4

–6

–8

2

4

6

8

GAIN – dB

±15V

±5V

+5V

FREQUENCY – Hz

1k

150

2pF

1k

V

IN

V

OUT

AD818

VS 0.1dB
FLATNESS

±15V 72 MHz

±5V 34 MHz

+5V 19 MHz

1G

–40

RL = 150

2V p-p

Ω

2nd HARMONIC

1k

3rd HARMONIC

1M100k10k

FREQUENCY – Hz

HARMONIC DISTORTION – dB

–50

–60

–70

–80

–90

–100

100

Figure 17. Harmonic Distortion vs. Frequency

650

550

450

10M

C

10

VS CC 0.1dB
Flatness

9

ⴞ15V 2pF 55 MHz
ⴞ5V 1pF 43 MHz

8

+5V 1pF 18 MHz

7

6

GAIN – dB

5

4

3

2

1

1M 10M 100M

ⴞ5V

+5V

FREQUENCY – Hz

1k

V

IN

1k

AD818

C

150

ⴞ15V

V

OUT

1G

Figure 20. Closed-Loop Gain vs. Frequency (G = +2)

SLEW RATE – V/µs

350

250

–60 140

–40

Figure 18. Slew Rate vs. Temperature

0.06

0.05

0.04

DIFFERENTIAL PHASE – Degrees

0.03

Figure 19. Differential Gain and Phase vs. Supply Voltage

REV. B

510

–20

0

TEMPERATURE – °C

100 12080604020

Figure 21. Closed-Loop Gain vs. Frequency (G = –1)

0.02

DIFF GAIN

DIFF PHASE

SUPPLY VOLTAGE – ±Volts

0.01

0.00

DIFFERENTIAL GAIN – Percent

15

–7–

A

A

AD818–Typical Characteristics

C

F

1k

Ω

+V

3.3µF

S

0.01µF

HP
PULSE (LS)
OR FUNCTION
(SS)
GENERATOR

V

Ω

1k

IN

50

Ω

2

3

7

AD818

4

–V

S

3.3µF

6

V

OUT

0.01µF

TEKTRONIX

P6201 FET

PROBE

R

L

TEKTRONIX

7A24

PREAMP

100

5V

90

10

0%

50ns

5V

Figure 22. Inverting Amplifier Connection

2V

50ns

100

90

10

0%

2V

Figure 23. Inverter Large Signal Pulse Response ±5 VS,

= 1 pF, RL = 1 k

C

F

100

90

Ω

200mV

10ns

Figure 25. Inverter Large Signal Pulse Response ±15 VS,

= 1 pF, RL = 1 k

C

F

100

90

10

0%

Ω

200mV

200mV

10ns

Figure 26. Inverter Small Signal Pulse Response ±15 VS,

= 1 pF, RL = 150

C

F

100

90

200mV

Ω

10ns

10

0%

200mV

Figure 24. Inverter Small Signal Pulse Response ±5 VS,

= 1 pF, RL = 150

C

F

Ω

10

0%

200mV

Figure 27. Inverter Small Signal Pulse Response ±5 VS,

= 0 pF, RL = 150

C

F

Ω

REV. B–8–

HP

A

PULSE (LS)
OR FUNCTION
(SS)
GENERATOR

AD818

C

F

1k

Ω

V

Ω

100

IN

Ω

50

2

3

1k

+V

S

7

AD818

4

–V

S

Ω

3.3µF

3.3µF

0.01µF

6

V

OUT

0.01µF

TEKTRONIX

P6201 FET

PROBE

R

L

TEKTRONIX

7A24

PREAMP

100

5V

90

10

0%

50ns

5V

Figure 28. Noninverting Amplifier Connection

2V

100

90

10

0%

2V

50ns

Figure 29. Noninverting Large Signal Pulse Response

±

5 V, CF = 1 pF, RL = 1 k

100mV

100

90

Ω

10ns

Figure 31. Noninverting Large Signal Pulse Response

±

15 V, CF = 1 pF, RL = 1 k

100mV

100

90

10

0%

Ω

10ns

200mV

Figure 32. Noninverting Small Signal Pulse Response

±

15 V, CF = 1 pF, RL = 150

100mV

100

90

Ω

10ns

10

0%

200mV

Figure 30. Noninverting Small Signal Pulse Response

±

5 V, CF = 1 pF, RL = 150

Ω

REV. B

10

0%

200mV

Figure 33. Noninverting Small Signal Pulse Response

±

5 V, CF = 0 pF, RL = 150

Ω

–9–

AD818

+V

S

OUTPUT

–IN

+IN

–V

S

NULL 1 NULL 8

Figure 34. AD818 Simplified Schematic

THEORY OF OPERATION

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 differ­ential 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.

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.

INPUT CONSIDERATIONS

An input protection resistor (RIN in Figure 28) is required in
circuits where the input to the AD818 will be subjected to tran­sient of continuous overload voltages exceeding the ±6 V maxi­mum differential limit. This resistor provides protection for the
input transistors by limiting their maximum base current.

For high performance circuits, it is recommended that a “bal­ancing” 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 R

IN

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.

may result in peaking. A small capacitance (1–5 pF) may be
used in parallel with the feedback resistor to neutralize this
effect.

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.

+V

S

7

2

1

6

8

10k⍀

VOS ADJUST

3

AD818

4

–V

S

Figure 35. Offset Null Configuration

OFFSET NULLING

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.

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.

Referring to Figure 36, careful consideration should be given to
the proper selection of component values. The choices for
this particular circuit are: R1 + R3储R2 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.

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 V

through

IN

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 R

.

L

+V

S

GROUNDING AND BYPASSING

When designing high frequency circuits, some special precau­tions are in order. Circuits must be built with short interconnect
leads. When wiring components, care should be taken to pro­vide a low resistance, low inductance path to ground. Sockets
should be avoided, since their increased interlead capacitance
can degrade circuit bandwidth.

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

–10–

R3

3.3␮F

V

IN

100⍀

C2

C1

0.01␮F

1k⍀

0.001␮F

R1

3.3k⍀

R2

3.3k⍀

R4

C4

1k⍀

2

AD818

3

7

4

SELECT C1, R1, R2
FOR DESIRED LOW

3.3␮F
FREQUENCY CORNER.

0.01␮F

6

V

OUT

Figure 36. Single Supply Amplifier Configuration

R

L

150⍀

C3

0.1␮F

REV. B

ERROR

SIGNAL

OUTPUT

ERROR AMPLIFIER
V

OUTPUT × 10

ERROR

2×
HP2835

3

AD829

2

AD818

15pF

Ω

2×

5

7

HP2835

6

4

0.47µF

1M

SHORT, DIRECT

Ω

100

CONNECTION TO
TEKTRONIX TYPE 11402
OSCILLOSCOPE PREAMP
INPUT SECTION

0 TO ±10V

POWER

SUPPLY

TTL LEVEL

SIGNAL

GENERATOR

50Hz

OUTPUT

DIGITAL

GROUND

ANALOG

GROUND

EI&S
DL1A05GM
MERCURY
RELAY

7, 8

2

13

1, 14

50

COAX

CABLE

Ω

2.2µF

500

50

ADJUST

1k

Ω

NULL

Ω

Ω

0.01µF

100

2

3

Ω

AD818

FALSE
SUMMING
NODE

500

Ω

7

+V

S

5–18pF

4

2.2µF

–V

S

Ω

1k

DEVICE
UNDER
TEST

6

0.01µF

Figure 37. Settling Time Test Circuit

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.

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.

A High Performance Video Line Driver

The buffer circuit shown in Figure 38 will drive a back-termi­nated 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 require­ments for high-definition video displays and test equipment, is
achieved using only 7 mA quiescent current.

+15V

0.01µF

V

IN

Rt

Ω

75

1k

Ω

2

AD818

3

1k

7

4

0.01µF

–15V

Ω

2.2µF

Rbt

75

Ω

Ω

2.2µF

75

Rt
75

Ω

6

0.01µF

100

Ω

0.47µF

+V

1.9k

Ω

NOTE:
USE CIRCUIT BOARD
WITH GROUND PLANE

10pF
SCOPE PROBE
CAPACITANCE

0.01µF

–V

S

S

TEKTRONIX P6201
FET PROBE TO
TEKTRONIX TYPE 11402
OSCILLOSCOPE
PREAMP INPUT SECTION

SETTLING
OUTPUT

DIFFERENTIAL LINE RECEIVER

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.

2pF

1k⍀ 1k⍀

+5V

2.2␮F

6

V

OUT

2.2␮F

OUTPUT

DIFFERENTIAL

INPUT

1k⍀

2

AD818

3

2pF

0.01␮F

7

4

0.01␮F

–5V

1k⍀

Figure 39. Differential Line Receiver

100

200

V

1V

90

2V

10

0%

10n

s

20ns

REV. B

Figure 38. Video Line Driver

200m
V

Figure 40. Performance of Line Receiver, RL = 150 Ω,
G = +2

–11–

AD818

A HIGH SPEED, THREE OP AMP IN AMP

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.

EACH

+15V

10µF

COMMON

10µF

–15V

–V

IN

A1

0.1µF

0.1µF

AD818

1k⍀

1k⍀

1k⍀

3pF

2pF

5pF

R

G

5pF

1k⍀

A2

R

G

1k⍀
222⍀
20⍀

AD818

CADJ
(pF)

2-8
2-8
2-8

SMALL
SIGNAL
BANDWIDTH

14.7 MHz

4.5 MHz
960 kHz

+V

IN

BANDWIDTH, SETTLING TIME, & TOTAL HARMONIC DISTORTION VS. GAIN

GAIN

3
10
100

+V

S

–V

S

AMPLIFIER

1µF

1µF

2-8 pF

970⍀

50⍀
D.C. CMR
ADJUST

SETTLING
TIME
TO 0.1%

200ns
370ns

2.5µs

PIN 7
EACH
AMPLIFIER

0.1µF

0.1µF

PIN 4
EACH
AMPLIFIER

SETTLING
TIME A.C.
CMR ADJUST

1k⍀

A3

AD817

THD + NOISE
BELOW INPUT LEVEL
@ 10kHz

82 dB
81 dB
71 dB

V

OUT

R

L

2k⍀

0.165±0.01
(4.19±0.25)

0.125

(3.18)

0.1574 (4.00)

0.1497 (3.80)

PIN 1

0.0098 (0.25)

0.0040 (0.10)

SEATING

OUTLINE DIMENSIONS

Dimensions shown in inches and (mm).

8-Lead Plastic Mini-DIP (N) Package

PIN 1

MIN

0.018±0.003
(0.46±0.08)

8

1

0.39 (9.91) MAX

0.10

(2.54)

BSC

4

0.033
(0.84)
NOM

5

0.25

(6.35)

0.035±0.01
(0.89±0.25)

0.18±0.03
(4.57±0.76)

SEATING
PLANE

0.31

(7.87)

0.30 (7.62)
REF

0.011±0.003
(0.28±0.08)

15°

0°

8-Lead SOIC (R) Package

0.1968 (5.00)

0.1890 (4.80)

85

0.0500 (1.27)

PLANE

41

BSC

0.0192 (0.49)

0.0138 (0.35)

0.2440 (6.20)

0.2284 (5.80)

0.0688 (1.75)

0.0532 (1.35)

0.0098 (0.25)

0.0075 (0.19)

0.0196 (0.50)

0.0099 (0.25)

8ⴗ

0.0500 (1.27)

0ⴗ

0.0160 (0.41)

C1738–0–5/00 (rev. B) 00872

ⴛ 45ⴗ

Figure 41. High Speed 3 Op Amp In Amp

–12–

PRINTED IN U.S.A.

REV. B