60 MHz 2000 V/μs
Monolithic Op Amp
AD844
FEATURES
Wide bandwidth
60 MHz at gain of −1
33 MHz at gain of −10
Slew rate: 2000 V/μs
20 MHz full power bandwidth, 20 V p-p, R
L
= 500 Ω
Fast settling: 100 ns to 0.1% (10 V step)
Differential gain error: 0.03% at 4.4 MHz
Differential phase error: 0.16° at 4.4 MHz
Low offset voltage: 150 μV maximum (B Grade)
Low quiescent current: 6.5 mA
Available in tape and reel in accordance with
EIA-481-A standard
FUNCTIONAL BLOCK DIAGRAMS
NULL
1
–IN
2
AD844
8
7
6
5
NULL
+V
S
OUTPUT
TZ
00897-001
+IN
3
–V
S 4
TOP VIEW
(Not to Scale)
Figure 1. 8-Lead PDIP (N) and 8-Lead CERDIP (Q) Packages
NC
1
OFFSETNULL
2
–IN
3
NC
4
+IN
5
NC
6
16
NC
15
OFFSETNULL
14
V+
13
NC
12
OUTPUT
APPLICATIONS
Flash ADC input amplifiers
High speed current DAC interfaces
Video buffers and cable drivers
Pulse amplifiers
NC = NO CONNECT
Figure 2. 16-Lead SOIC (R) Package
GENERAL DESCRIPTION
The AD844 is a high speed monolithic operational amplifier
fabricated using the Analog Devices, Inc., junction isolated
complementary bipolar (CB) process. It combines high band-
width and very fast large signal response with excellent dc
performance. Although optimized for use in current-to-voltage
applications and as an inverting mode amplifier, it is also suitable
for use in many noninverting applications.
The AD844 can be used in place of traditional op amps, but its
current feedback architecture results in much better ac perfor-
mance, high linearity, and an exceptionally clean pulse response.
This type of op amp provides a closed-loop bandwidth that is
determined primarily by the feedback resistor and is almost
independent of the closed-loop gain. The AD844 is free from
the slew rate limitations inherent in traditional op amps and
other current-feedback op amps. Peak output rate of change can
be over 2000 V/μs for a full 20 V output step. Settling time is
typically 100 ns to 0.1%, and essentially independent of gain.
The AD844 can drive 50 Ω loads to ±2.5 V with low distortion
and is short-circuit protected to 80 mA.
The AD844 is available in four performance grades and three
package options. In the 16-lead SOIC (RW) package, the AD844J
is specified for the commercial temperature range of 0°C to 70°C.
The AD844A and AD844B are specified for the industrial
temperature range of −40°C to +85°C and are available in the
CERDIP (Q) package. The AD844A is also available in an 8-lead
PDIP (N). The AD844S is specified over the military temperature
range of −55°C to +125°C. It is available in the 8-lead CERDIP
(Q) package. A and S grade chips and devices processed to
MIL-STD-883B, Rev. C are also available.
PRODUCT HIGHLIGHTS
1.
2.
3.
The AD844 is a versatile, low cost component providing an
excellent combination of ac and dc performance.
It is essentially free from slew rate limitations. Rise and fall
times are essentially independent of output level.
The AD844 can be operated from ±4.5 V to ±18 V power
supplies and is capable of driving loads down to 50 Ω, as
well as driving very large capacitive loads using an external
network.
The offset voltage and input bias currents of the AD844 are
laser trimmed to minimize dc errors; V
OS
drift is typically 1
μV/°C and bias current drift is typically 9 nA/°C.
The AD844 exhibits excellent differential gain and
differential phase characteristics, making it suitable for a
variety of video applications with bandwidths up to 60 MHz.
The AD844 combines low distortion, low noise, and low
drift with wide bandwidth, making it outstanding as an
input amplifier for flash analog-to-digital converters (ADCs).
4.
5.
6.
Rev. F
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 that may result from its use. Specifications subject to change without notice. No
license is granted by implication or otherwise under any patent or patent rights of Analog Devices.
Trademarks and registered trademarks are the property of their respective owners.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700
www.analog.com
Fax: 781.461.3113 ©1989–2009 Analog Devices, Inc. All rights reserved.
00897-002
10
NC
V–
7
TOP VIEW
NC
8
(Not to Scale)
9
NC
AD844
11
TZ
AD844
TABLE OF CONTENTS
Features .............................................................................................. 1
Applications ....................................................................................... 1
Functional Block Diagrams ............................................................. 1
General Description ......................................................................... 1
Product Highlights ........................................................................... 1
Revision History ............................................................................... 2
Specifications..................................................................................... 3
Absolute Maximum Ratings............................................................ 5
Metallization Photograph ............................................................ 5
ESD Caution .................................................................................. 5
Typical Performance Characteristics ............................................. 6
Inverting Gain-of-1 AC Characteristics .................................... 8
Inverting Gain-of-10 AC Characteristics .................................. 9
Inverting Gain-of-10 Pulse Response ...................................... 10
Noninverting Gain-of-10 AC Characteristics ........................ 11
Understanding the AD844 ............................................................ 12
Open-Loop Behavior ................................................................. 12
Response as an Inverting Amplifier ......................................... 12
Response as an I-V Converter .................................................. 13
Circuit Description of the AD844 ............................................ 13
Response as a Noninverting Amplifier.................................... 14
Noninverting Gain of 100 ......................................................... 14
Using the AD844 ............................................................................ 15
Board Layout ............................................................................... 15
Input Impedance ........................................................................ 15
Driving Large Capacitive Loads ............................................... 15
Settling Time ............................................................................... 15
DC Error Calculation ................................................................ 16
Noise ............................................................................................ 16
Video Cable Driver Using ±5 V Supplies ................................ 16
High Speed DAC Buffer ............................................................ 17
20 MHz Variable Gain Amplifier ............................................. 17
Outline Dimensions ....................................................................... 19
Ordering Guide .......................................................................... 20
REVISION HISTORY
2/09—Rev. E to Rev F
Updated Format .................................................................. Universal
Changes to Features Section............................................................ 1
Changes to Differential Phase Error Parameter, Table 1 ............. 3
Changes to Figure 13 ........................................................................ 8
Changes to Figure 18 ........................................................................ 9
Changes to Figure 23 and Figure 24 ............................................. 11
Changes to Figure 42 and High Speed DAC Buffer Section ..... 17
Updated Outline Dimensions ....................................................... 19
Changes to Ordering Guide .......................................................... 20
1/03 Data Sheet changed from REV. D to REV. E.
Updated Features ...............................................................................1
Edit to TPC 18 ...................................................................................7
Edits to Figure 13 and Figure 14................................................... 13
Updated Outline Dimensions ....................................................... 15
11/01 Data Sheet changed from REV. C to REV. D.
Edits to Specifications ......................................................................2
Edits to Absolute Maximum Ratings ..............................................3
Edits to Ordering Guide ...................................................................3
Rev. F | Page 2 of 20
AD844
SPECIFICATIONS
T
A
= 25°C and V
S
= ±15 V dc, unless otherwise noted.
Table 1.
Parameter
INPUT OFFSET VOLTAGE
1
T
MIN
to T
MAX
vs. Temperature
vs. Supply
Initial
T
MIN
to T
MAX
vs. Common Mode
Initial
T
MIN
to T
MAX
INPUT BIAS CURRENT
Negative Input Bias Current
1
T
MIN
to T
MAX
vs. Temperature
vs. Supply
Initial
T
MIN
to T
MAX
vs. Common Mode
Initial
T
MIN
to T
MAX
Positive Input Bias Current
1
T
MIN
to T
MAX
vs. Temperature
vs. Supply
Initial
T
MIN
to T
MAX
vs. Common Mode
Initial
T
MIN
to T
MAX
INPUT CHARACTERISTICS
Input Resistance
Negative Input
Positive Input
Input Capacitance
Negative Input
Positive Input
Input Common-Mode Voltage
Range
INPUT VOLTAGE NOISE
INPUT CURRENT NOISE
Negative Input
Positive Input
OPEN-LOOP TRANSRESISTANCE
T
MIN
to T
MAX
Transcapacitance
DIFFERENTIAL GAIN ERROR
2
DIFFERENTIAL PHASE ERROR
2
Conditions
AD844J/AD844A
Min
Typ
Max
50
300
75
500
1
4
4
V
CM
= ±10 V
10
10
200
800
9
5 V to 18 V
175
220
V
CM
= ±10 V
90
110
150
350
3
5 V to 18 V
80
100
V
CM
= ±10 V
90
130
150
90
130
120
190
90
140
150
200
nA/V
nA/V
150
80
100
100
120
80
120
150
200
nA/V
nA/V
160
400
700
90
110
100
300
3
110
150
200
500
7
90
120
100
800
7
160
200
400
1300
15
nA/V
nA/V
nA
nA
nA/°C
250
175
220
200
240
175
220
250
300
nA/V
nA/V
35
10
10
150
750
9
20
20
250
1100
15
10
10
200
1900
20
35
35
450
2500
30
μV/V
μV/V
nA
nA
nA/°C
20
Min
AD844B
Typ
50
75
1
4
4
Max
150
200
5
10
10
Min
AD844S
Typ
50
125
1
4
4
Max
300
500
5
20
20
Unit
μV
μV
μV/°C
μV/V
μV/V
5 V to 18 V
450
1500
7
50
10
2
2
65
7
50
10
2
2
65
7
50
10
2
2
65
Ω
MΩ
pF
pF
V
nV/√Hz
pV/√Hz
pV/√Hz
MΩ
MΩ
pF
%
Degree
±10
f ≥ 1 kHz
f ≥ 1 kHz
f ≥ 1 kHz
V
OUT
= ±10 V
R
L
= 500 Ω
2
10
12
2.2
1.3
3.0
2.0
4.5
0.03
0.16
Rev. F | Page 3 of 20
±10
2
10
12
2.8
1.6
3.0
2.0
4.5
0.03
0.16
±10
2
10
12
2.2
1.3
3.0
1.6
4.5
0.03
0.16
f = 4.4 MHz
f = 4.4 MHz
AD844
Parameter
FREQUENCY RESPONSE
Small Signal Bandwidth
3, 4
Gain = −1
Gain = −10
TOTAL HARMONIC DISTORTION
SETTLING TIME
10 V Output Step
Gain = −1, to 0.1%
5
Gain = −10, to 0.1%
6
2 V Output Step
Gain = −1, to 0.1%
5
Gain = −10, to 0.1%
6
OUTPUT SLEW RATE
FULL POWER BANDWIDTH
V
OUT
= 20 V p-p
5
V
OUT
= 2 V p-p
5
OUTPUT CHARACTERISTICS
Voltage
Short-Circuit Current
T
MIN
to T
MAX
Output Resistance
POWER SUPPLY
Operating Range
Quiescent Current
T
MIN
to T
MAX
1
2
Conditions
AD844J/AD844A
Min
Typ
Max
Min
AD844B
Typ
Max
Min
AD844S
Typ
Max
Unit
f = 100 kHz,
2 V rms
5
±15 V supplies
60
33
0.005
60
33
0.005
60
33
0.005
MHz
MHz
%
100
100
±5 V supplies
110
100
2000
100
100
110
100
2000
100
100
110
100
2000
ns
ns
ns
ns
V/μs
Overdriven
input
THD = 3%
V
S
= ±15 V
V
S
= ±5 V
R
L
= 500 Ω
1200
1200
1200
20
20
±10
±11
80
60
15
±18
7.5
8.5
±10
20
20
±11
80
60
15
±18
7.5
8.5
±10
20
20
±11
80
60
15
±18
7.5
8.5
MHz
MHz
V
mA
mA
Ω
V
mA
mA
Open loop
±4.5
±4.5
6.5
7.5
±4.5
6.5
7.5
6.5
7.5
Rated performance after a 5 minute warm-up at T
A
= 25°C.
Input signal 285 mV p-p carrier (40 IRE) riding on 0 mV to 642 mV (90 IRE) ramp. R
L
= 100 Ω; R1, R2 = 300 Ω.
3
For gain = −1, input signal = 0 dBm, C
L
= 10 pF, R
L
= 500 Ω, R1 = 500 Ω, and R2 = 500 Ω in Figure 29.
4
For gain = −10, input signal = 0 dBm, C
L
=10 pF, R
L
= 500 Ω, R1 = 500 Ω, and R2 = 50 Ω in Figure 29.
5
C
L
= 10 pF, R
L
= 500 Ω, R1 = 1 kΩ, R2 = 1 kΩ in Figure 29.
6
C
L
= 10 pF, R
L
= 500 Ω, R1 = 500 Ω, R2 = 50 Ω in Figure 29.
Rev. F | Page 4 of 20
AD844
ABSOLUTE MAXIMUM RATINGS
Table 2.
Parameter
Supply Voltage
Power Dissipation
1
Output Short-Circuit Duration
Input Common-Mode Voltage
Differential Input Voltage
Inverting Input Current
Continuous
Transient
Storage Temperature Range (Q)
Storage Temperature Range (N, RW)
Lead Temperature (Soldering, 60 sec)
ESD Rating
1
METALLIZATION PHOTOGRAPH
Ratings
±18
V
1.1 W
Indefinite
±V
S
6V
5 mA
10 mA
−65°C to +150°C
−65°C to +125°C
300°C
1000 V
Contact factory for latest dimensions.
Dimensions shown in inches and (millimeters).
–IN
NULL
NULL
+V
S
0.076
(1.9)
28-lead PDIP package: θ
JA
= 90°C/W.
8-lead CERDIP package: θ
JA
= 110°C/W.
16-lead SOIC package: θ
JA
= 100°C/W.
+IN
–V
S
0.095
(2.4)
SUBSTRATE CONNECTED TO +V
S
TZ
OUTPUT
00897-003
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.
Figure 3. Die Photograph
ESD CAUTION
Rev. F | Page 5 of 20
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