Analog Devices AD8138 Datasheet
Low Distortion
1
2
3
4
8
7
6
5
AD8138
NC
V
OCM
–OUT
V+
NC = NO CONNECT
+IN
V–
–IN
+OUT
a
FEATURES
Easy to Use Single-Ended-to-Differential Conversion
Adjustable Output Common-Mode Voltage
Externally Adjustable Gain
Low Harmonic Distortion
–94 dBc—Second, <–114 dBc—Third @ 5 MHz into
800 ⍀ Load
–87 dBc—Second, –85 dBc—Third @ 20 MHz into
800 ⍀ Load
–3 dB Bandwidth of 320 MHz, G = +1
Fast Settling to 0.01% of 16 ns
Slew Rate 1150 V/s
Fast Overdrive Recovery of 4 ns
Low Input Voltage Noise of 5 nV/√Hz
1 mV Typical Offset Voltage
Wide Supply Range +3 V to ⴞ5 V
Low Power 90 mW on +5 V
0.1 dB Gain Flatness to 40 MHz
Available in 8-Lead SOIC
APPLICATIONS
ADC Driver
Single-Ended-to-Differential Converter
IF and Baseband Gain Block
Differential Buffer
Line Driver
Differential ADC Driver
AD8138
FUNCTIONAL BLOCK DIAGRAM
TYPICAL APPLICATION CIRCUIT
AVDD DVDD
AIN
AIN
AVSS
+5V
ADC
DIGITAL
V
REF
OUTPUTS
+5V
499V
V
IN
499V
V
499V
OCM
+
AD8138
–
499V
PRODUCT DESCRIPTION
AD8138 is a major advancement over op amps for differential
signal processing. The AD8138 can be used as a single-endedto-differential amplifier or as a differential-to-differential amplifier. The AD8138 is as easy to use as an op amp, and greatly
simplifies differential signal amplification and driving.
Manufactured on ADI’s proprietary XFCB bipolar process, the
AD8138 has a –3 dB bandwidth of 320 MHz and delivers a
differential signal with the lowest harmonic distortion available
in a differential amplifier. The AD8138 has a unique internal
feedback feature that provides output gain and phase matching
that are balanced, suppressing even order harmonics. The internal feedback circuit also minimizes any gain error that would be
associated with the mismatches in the external gain setting
resistors.
The AD8138’s differential output helps balance the input-todifferential ADCs, maximizing the performance of the ADC.
The AD8138 eliminates the need for a transformer with high
REV. A
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.
performance ADCs, preserving the low frequency and dc information. The common-mode level of the differential output is
adjustable by a voltage on the V
pin, easily level-shifting
OCM
the input signals for driving single supply ADCs. Fast overload
recovery preserves sampling accuracy.
The AD8138 distortion performance makes it an ideal ADC
driver for communication systems, with distortion performance
good enough to drive state-of-the-art 10- to 16-bit converters
at high frequencies. The AD8138’s high bandwidth and IP3
also make it appropriate for use as a gain block in IF and
baseband signal chains. The AD8138 offset and dynamic performance make it well suited for a wide variety of signal processing and data acquisition applications.
The AD8138 is offered in an 8-lead SOIC that operates over
the industrial temperature range of –40°C to +85°C.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781/329-4700 World Wide Web Site: http://www.analog.com
Fax: 781/326-8703 © Analog Devices, Inc., 1999
AD8138–SPECIFICATIONS
(@ +25ⴗC, VS = ⴞ5 V, V
= 0, G = +1, R
OCM
= 500 ⍀, unless otherwise noted.
L,dm
Refer to Figure 1 for test setup and label descriptions. All specifications refer to single-ended input and differential outputs unless noted.)
AD8138
Parameter Conditions Min Typ Max Units
ⴞDIN to ⴞOUT Specifications
DYNAMIC PERFORMANCE
–3 dB Small Signal Bandwidth V
Bandwidth for 0.1 dB Flatness V
Large Signal Bandwidth V
Slew Rate V
Settling Time 0.01%, V
Overdrive Recovery Time VIN = 5 V to 0 V Step, G = +2 4 ns
NOISE/HARMONIC PERFORMANCE
Second Harmonic V
Third Harmonic V
IMD 20 MHz –77 dBc
IP3 20 MHz 37 dBm
Voltage Noise (RTI) f = 100 kHz to 40 MHz 5 nV/√Hz
Input Current Noise f = 100 kHz to 40 MHz 2 pA/√Hz
INPUT CHARACTERISTICS
Offset Voltage V
Input Bias Current 3.5 7 µA
Input Resistance Differential 6 MΩ
Input Capacitance 1pF
Input Common-Mode Voltage –4.7 – +3.4 V
CMRR ∆V
OUTPUT CHARACTERISTICS
Output Voltage Swing Maximum ∆V
Output Current 95 mA
Output Balance Error ∆V
V
to ⴞOUT Specifications
OCM
DYNAMIC PERFORMANCE
–3 dB Bandwidth 250 MHz
Slew Rate 330 V/µs
DC PERFORMANCE
Input Voltage Range ±3.8 V
Input Resistance 200 kΩ
Input Offset Voltage V
Input Bias Current 0.5 µA
V
CMRR [∆V
OCM
Gain ∆V
POWER SUPPLY
Operating Range ±1.4 ±5.5 V
Quiescent Current 18 20 23 mA
Power Supply Rejection Ratio ∆V
OPERATING TEMPERATURE RANGE –40 +85 °C
NOTES
Harmonic Distortion Performance is equal or slightly worse with higher values of R
Specifications subject to change without notice.
= 0.5 V p-p, CF = 0 pF 290 320 MHz
OUT
V
= 0.5 V p-p, CF = 1 pF 225 MHz
OUT
= 0.5 V p-p, CF = 0 pF 30 MHz
OUT
= 2 V p-p, CF = 0 pF 265 MHz
OUT
= 2 V p-p, C
OUT
OUT
= 2 V p-p, 5 MHz, R
OUT
V
= 2 V p-p, 20 MHz, R
OUT
V
= 2 V p-p, 70 MHz, R
OUT
= 2 V p-p, 5 MHz, R
OUT
V
= 2 V p-p, 20 MHz, R
OUT
V
= 2 V p-p, 70 MHz, R
OUT
= V
OS,dm
T
MIN–TMAX
T
MIN–TMAX
OUT,dm
= 0 pF 1150 V/µs
F
= 2 V p-p, CF = 1 pF 16 ns
= 800 Ω –94 dBc
L,dm
= 800 Ω –87 dBc
L,dm
= 800 Ω –62 dBc
L,dm
= 800 Ω –114 dBc
L,dm
= 800 Ω –85 dBc
L,dm
= 800 Ω –57 dBc
L,dm
/2; V
DIN+
= V
DIN–
= V
= 0 V –2.5 ±1 2.5 mV
OCM
Variation ±4 µV/°C
Variation –0.01 µA/°C
Common Mode 3 MΩ
/∆V
T
OUT,dm
/∆V
OUT,cm
= V
OS,cm
OUT,dm
/∆V
OUT,cm
to T
MIN
/∆VS; ∆VS = ±1 V –90 –70 dB
OUT,dm
; ∆V
IN,cm
; Single-Ended Output 7.75 V p-p
OUT
OUT,dm
; V
OUT,cm
/∆V
]; ∆V
OCM
OCM; ∆VOCM
Variation 40 µA/°C
MAX
= ±1 V –75 –70 dB
IN,cm
; ∆V
DIN+
= 1 V –66 dB
OUT,dm
= V
OCM
DIN–
= V
= 0 V –3.5 ±1 3.5 mV
OCM
= ±1 V –75 dB
= ±1 V 0.9955 1 1.0045 V/V
. See Figures 14 and 15 for more information.
L,dm
–2–
REV. A
AD8138
SPECIFICATIONS
(@ +25ⴗC, VS = +5 V, V
for test setup and label descriptions. All specifications refer to single-ended input and differential outputs unless noted.)
Parameter Conditions Min Typ Max Units
ⴞDIN to ⴞOUT Specifications
DYNAMIC PERFORMANCE
–3 dB Small Signal Bandwidth V
Bandwidth for 0.1 dB Flatness V
Large Signal Bandwidth V
Slew Rate V
Settling Time 0.01%, V
Overdrive Recovery Time VIN = 2.5 V to 0 V Step, G = +2 4 ns
NOISE/HARMONIC PERFORMANCE
Second Harmonic V
Third Harmonic V
IMD 20 MHz –74 dBc
IP3 20 MHz 35 dBm
Voltage Noise (RTI) f = 100 kHz to 40 MHz 5 nV/√Hz
Input Current Noise f = 100 kHz to 40 MHz 2 pA/√Hz
INPUT CHARACTERISTICS
Offset Voltage V
Input Bias Current 3.5 7 µA
Input Resistance Differential 6 MΩ
Input Capacitance 1pF
Input Common-Mode Voltage –0.3 – +3.2 V
CMRR ∆V
OUTPUT CHARACTERISTICS
Output Voltage Swing Maximum ∆V
Output Current 95 mA
Output Balance Error ∆V
V
to ⴞOUT Specifications
OCM
DYNAMIC PERFORMANCE
–3 dB Bandwidth 220 MHz
Slew Rate 250 V/µs
DC PERFORMANCE
Input Voltage Range +1.0 – +3.8 V
Input Resistance 100 kΩ
Input Offset Voltage V
Input Bias Current 0.5 µA
V
CMRR [∆V
OCM
Gain ∆V
POWER SUPPLY
Operating Range 2.7 11 V
Quiescent Current 15 20 21 mA
Power Supply Rejection Ratio ∆V
OPERATING TEMPERATURE RANGE –40 +85 °C
NOTES
Harmonic Distortion Performance is equal or slightly worse with higher values of R
Specifications subject to change without notice.
= 0.5 V p-p, CF = 0 pF 280 310 MHz
OUT
V
= 0.5 V p-p, CF = 1 pF 225 MHz
OUT
= 0.5 V p-p, CF = 0 pF 29 MHz
OUT
= 2 V p-p, CF = 0 pF 265 MHz
OUT
= 2 V p-p, C
OUT
= 2 V p-p, 5 MHz, R
OUT
V
= 2 V p-p, 20 MHz, R
OUT
V
= 2 V p-p, 70 MHz, R
OUT
= 2 V p-p, 5 MHz, R
OUT
V
= 2 V p-p, 20 MHz, R
OUT
V
= 2 V p-p, 70 MHz, R
OUT
= V
OS,dm
T
MIN–TMAX
T
MIN–TMAX
Common Mode 3 MΩ
OUT,dm
OUT,cm
= V
OS,cm
OUT,dm
OUT,cm
T
to T
MIN
OUT,dm
= +2.5 V, G = +1, R
OCM
= 500 ⍀, unless otherwise noted. Refer to Figure 1
L,dm
AD8138
= 0 pF 950 V/µs
F
= 2 V p-p, CF = 1 pF 16 ns
OUT
= 800 Ω –90 dBc
L,dm
= 800 Ω –79 dBc
L,dm
= 800 Ω –60 dBc
L,dm
= 800 Ω –100 dBc
L,dm
= 800 Ω –82 dBc
L,dm
= 800 Ω –53 dBc
L,dm
OUT,dm
/2; V
DIN+
= V
DIN–
= V
= 2.5 V –2.5 ±12.5mV
OCM
Variation ±4 µV/°C
Variation –0.01 µA/°C
/∆V
; ∆V
IN,cm
OUT
/∆V
OUT,dm
; V
OUT,cm
/∆V
OCM
/∆V
OCM; ∆VOCM
Variation 40 µA/°C
MAX
= 1 V –75 –70 dB
IN,cm
; Single-Ended Output 2.9 V p-p
; ∆V
DIN+
]; ∆V
= 1 V –65 dB
OUT,dm
= V
OCM
DIN–
= V
= 2.5 V –5 ±15mV
OCM
= 2.5 ± 1 V –70 dB
= 2.5 ± 1 V 0.9968 1 1.0032 V/V
/∆VS; ∆VS = ±1 V –90 –70 dB
. See Figures 14 and 15 for more information.
L,dm
–3–REV. A
AD8138
1
2
3
4
8
7
6
5
AD8138
NC
V
OCM
–OUT
V+
NC = NO CONNECT
+IN
V–
–IN
+OUT
ABSOLUTE MAXIMUM RATINGS
1
Supply Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ±5.5 V
V
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ±V
OCM
Internal Power Dissipation . . . . . . . . . . . . . . . . . . . . 550 mW
2
θ
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 155°C/W
JA
S
Operating Temperature Range . . . . . . . . . . . –40°C to +85°C
Storage Temperature Range . . . . . . . . . . . . –65°C to +150°C
Lead Temperature (Soldering 10 sec) . . . . . . . . . . . . +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 listed in the operational section of this
specification is not implied. Exposure to Absolute Maximum Ratings for any
extended periods may affect device reliability.
2
Thermal resistance measured on SEMI standard 4-layer board.
R
= 499V
F
RG = 499V
49.9V
R
G
24.9V
= 499V
AD8138
RF = 499V
R
= 499V
L,dm
Figure 1. Basic Test Circuit
PIN FUNCTION DESCRIPTIONS
Pin No. Name Function
1 –IN Negative Input Summing Node.
2V
Voltage applied to this pin sets the common-
OCM
mode output voltage with a ratio of 1:1. For
example, +1 V dc on V
will set the dc
OCM
bias level on +OUT and –OUT to +1 V.
3 V+ Positive Supply Voltage.
4 +OUT Positive Output. Note: the voltage at –D
is
IN
inverted at +OUT.
5 –OUT Negative Output. Note: the voltage at +D
IN
is inverted at –OUT.
6 V– Negative Supply Voltage.
7 NC No Connect.
8 +IN Positive Input Summing Node
PIN CONFIGURATION
ORDERING GUIDE
Model Temperature Range Package Descriptions Package Options
AD8138AR –40°C to +85°C 8-Lead SOIC SO-8
AD8138AR-REEL
AD8138AR-REEL7
1
2
–40°C to +85°C 13" Tape and Reel SO-8
–40°C to +85°C 7" Tape and Reel SO-8
AD8138-EVAL Evaluation Board
NOTES
1
13" Reels of 2500 each.
2
7" Reels of 750 each.
CAUTION
ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily
accumulate on the human body and test equipment and can discharge without detection.
WARNING!
Although the AD8138 features proprietary ESD protection circuitry, permanent damage may
occur on devices subjected to high energy electrostatic discharges. Therefore, proper ESD
precautions are recommended to avoid performance degradation or loss of functionality.
ESD SENSITIVE DEVICE
–4–
REV. A
Typical Performance Characteristics–
AD8138
Unless otherwise noted, GAIN = 1, RG = RF = R
6
3
0
GAIN – dB
–3
–6
–9
1
10 100
FREQUENCY – MHz
Figure 2. Small Signal Frequency
Response
6
GAIN – dB
–3
–6
3
0
VS = +5V
VS = +5V
VS = 65V
VS = 65V
VIN = 0.2V p-p
= 0pF
C
F
VIN = 2V p-p
= 0pF
C
F
1000
= 499 ⍀, TA = +25ⴗC; Refer to Figure 1 for test setup.
L,dm
GAIN – dB
6
3
0
–3
–6
–9
1
10 100
FREQUENCY – MHz
CF = 0pF
CF = 1pF
VS = 65V
= 0.2V p-p
V
IN
1000
Figure 3. Small Signal Frequency
Response
GAIN – dB
6
3
0
–3
–6
CF = 1pF
VIN = 2V p-p
= 65V
V
S
CF = 0pF
0.5
VS = 65V
= 0.2V p-p
V
IN
0.3
0.1
GAIN – dB
–0.1
–0.3
–0.5
1
10 100
FREQUENCY – MHz
Figure 4. 0.1 dB Flatness vs.
Frequency
30
20
10
GAIN – dB
G = 10, RF = 4.99kV
G = 5, RF = 2.49kV
G = 2, RF = 1kV
G = 1, RF = 499V
0
VS = 65V
C
F
V
OUT
R
G
CF = 0pF
CF = 1pF
= 0pF
= 0.2V p-p
,dm
= 499V
–9
1
10 100
FREQUENCY – MHz
Figure 5. Large Signal Frequency
Response
–50
V
= 2V p-p
,dm
OUT
R
= 800V
L
–60
–70
HD2(VS = +5V)
–80
–90
DISTORTION – dBc
–100
–110
–120
HD3(VS = 65V)
010 70
20 30 40 50 60
FUNDAMENTAL FREQUENCY – MHz
HD2(VS = 65V)
HD3(VS = +5V)
Figure 8. Harmonic Distortion vs.
Frequency
1000
–9
1
10 100
FREQUENCY – MHz
1000
Figure 6. Large Signal Frequency
Response
–40
V
= 4V p-p
,dm
OUT
R
= 800V
L
–50
–60
–70
–80
DISTORTION – dBc
–90
–100
–110
HD3(VS = +5V)
HD2(VS = +5V)
HD2(VS = 65V)
HD3(VS = 65V)
010 70
20 30 40 50 60
FUNDAMENTAL FREQUENCY – MHz
Figure 9. Harmonic Distortion vs.
Frequency
–10
1
10 100
FREQUENCY – MHz
1000
Figure 7. Small Signal Frequency
Response for Various Gains
–30
V
= 2V p-p
,dm
OUT
= 800V
R
L
–40
F
= 20MHz
O
–50
–60
–70
DISTORTION – dBc
–80
–90
–100
–4 –3 3
HD3(VS = +5)
HD3(VS = 65)
HD2(VS = 65)
–2 –1 0 1 2
V
DC OUTPUT – Volts
OCM
HD2(VS = +5)
Figure 10. Harmonic Distortion vs.
V
OCM
4
–5–REV. A
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