Analog Devices AD8138 e Datasheet

Low Distortion

Differential ADC Driver

AD8138

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 and MSOP Packages

APPLICATIONS
ADC Driver
Single-Ended-to-Differential Converter
IF and Baseband Gain Block
Differential Buffer
Line Driver

PIN CONFIGURATION

1

–IN

V

2

OCM

V+

3

4

+OUT

NC = NO CONNECT

AD8138

+IN

8

NC

7

V–

6

–OUT

5

TYPICAL APPLICATION CIRCUIT

AVDD DVDD

AIN

AIN

AVSS

+5V

ADC

DIGITAL

V

REF

OUTPUTS

+5V

499⍀

V

499⍀

IN

499⍀

V

OCM

+

AD8138

–

499⍀

PRODUCT DESCRIPTION

The 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 balanced output gain and phase
matching, 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.

REV. E

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. 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 companies.

The AD8138 eliminates the need for a transformer with high
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 the

OCM

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-bit 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 available in both SOIC and MSOP packages for
operation over –40∞C to +85∞C temperatures.

One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: [phone] www.analog.com
Fax: [phone] © 2003 Analog Devices, Inc. All rights reserved.

AD8138–SPECIFICATIONS

(@ 25ⴗC, VS = ⴞ5 V, V

= 0, G = +1, R

OCM

= 500 ⍀, unless otherwise noted. Refer

L,dm

to Figure 1 for test setup and label descriptions. All specifications refer to single-ended input and differential outputs unless otherwise noted.)

Parameter Conditions Min Typ Max Unit

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 mA

Input Resistance Differential 6 MW

Input Capacitance 1pF
Input Common-Mode Voltage –4.7 to +3.4 V
CMRR DV

OUTPUT CHARACTERISTICS

Output Voltage Swing Maximum DV
Output Current 95 mA
Output Balance Error DV

V

to ⴞOUT Specifications

OCM

DYNAMIC PERFORMANCE

–3 dB Bandwidth 250 MHz
Slew Rate 330 V/ms

NPUT VOLTAGE NOISE (RTI) f = 0.1 MHz to 100 MHz 17 nV/÷Hz

DC PERFORMANCE

Input Voltage Range ±3.8 V
Input Resistance 200 kW
Input Offset Voltage V
Input Bias Current 0.5 mA

CMRR DV

V

OCM

Gain DV

POWER SUPPLY

Operating Range ±1.4 ±5.5 V
Quiescent Current 18 20 23 mA

Power Supply Rejection Ratio DV

OPERATING TEMPERATURE RANGE –40 +85 ∞C

*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

= 0.5 V p-p, CF = 1 pF 225 MHz

V

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, CF = 0 pF 1150 V/ms

V
V

V
V

T

T

OUT

OUT

OUT

OUT

OUT

OUT

OUT

OS,dm

MIN

MIN

= 2 V p-p, CF = 1 pF 16 ns

OUT

= 2 V p-p, 5 MHz, R
= 2 V p-p, 20 MHz, R
= 2 V p-p, 70 MHz, R
= 2 V p-p, 5 MHz, R
= 2 V p-p, 20 MHz, R
= 2 V p-p, 70 MHz, R

= V

to T

to T

/2; V

OUT,dm

MAX

MAX

DIN+

Variation ±4 mV/∞C

Variation –0.01 mA/∞C

= 800 W –94 dBc

L,dm

= 800 W –87 dBc

L,dm

= 800 W –62 dBc

L,dm

= 800 W –114 dBc

L,dm

= 800 W –85 dBc

L,dm

= 800 W –57 dBc

L,dm

= V

DIN–

= V

= 0 V –2.5 ±1 +2.5 mV

OCM

Common Mode 3 MW

/DV

T

OUT,dm

/DV

OUT,cm

= V

OS,cm

/DV

OUT,dm

/DV

OUT,cm

to T

MIN

/DVS; DVS = ± 1 V –90 –70 dB

OUT,dm

; DV

IN,cm

; Single-Ended Output 7.75 V p-p

OUT

OUT,dm

; V

OUT,cm

; DV

OCM

OCM; DVOCM

Variation 40 mA/∞C

MAX

= ± 1 V –77 –70 dB

IN,cm

; DV

DIN+

OCM

= 1 V –66 dB

OUT,dm

= V

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 TPCs 13 and 14 for more information.

L,dm

REV. E–2–

AD8138

SPECIFICATIONS

(@ 25ⴗC, VS = 5 V, V
setup and label descriptions. All specifications refer to single-ended input and differential output, unless

= 2.5 V, G = +1, R

OCM

= 500 ⍀, unless otherwise noted. Refer to Figure 1 for test

L,dm

otherwise noted.)

Parameter Conditions Min Typ Max Unit

ⴞ

DIN 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 mA

Input Resistance Differential 6 MW

Input Capacitance 1pF
Input Common-Mode Voltage 0.3 to 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/ms

INPUT VOLTAGE NOISE (RTI) f = 0.1 MHz to 100 MHz 17 nV/÷Hz

DC PERFORMANCE

Input Voltage Range 1.0 to 3.8 V
Input Resistance 100 kW
Input Offset Voltage V
Input Bias Current 0.5 mA

CMRR ⌬V

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

*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

= 0.5 V p-p, CF = 1 pF 225 MHz

V

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, CF = 0 pF 950 V/ms

V
V

V
V

T

T

OUT

OUT

OUT

OUT

OUT

OUT

OUT

OS,dm

MIN

MIN

= 2 V p-p, CF = 1 pF 16 ns

OUT

= 2 V p-p, 5 MHz, R
= 2 V p-p, 20 MHz, R
= 2 V p-p, 70 MHz, R
= 2 V p-p, 5 MHz, R
= 2 V p-p, 20 MHz, R
= 2 V p-p, 70 MHz, R

= V

to T

to T

/2; V

OUT,dm

MAX

MAX

DIN+

Variation ± 4 mV/∞C

Variation –0.01 mA/∞C

= 800 W –90 dBc

L,dm

= 800 W –79 dBc

L,dm

= 800 W –60 dBc

L,dm

= 800 W –100 dBc

L,dm

= 800 W –82 dBc

L,dm

= 800 W –53 dBc

L,dm

= V

= V

DIN–

= 0 V –2.5 ± 1 +2.5 mV

OCM

Common Mode 3 MW

/⌬V

T

OUT,dm

OUT,cm

OS,cm

OUT,dm

OUT,cm

MIN

OUT,dm

= V

to T

; ⌬V

IN,cm

OUT

/⌬V

OUT,dm

; V

OUT,cm

/⌬V

; ⌬V

OCM

/⌬V

OCM; ⌬VOCM

Variation 40 mA/∞C

MAX

/⌬VS; ⌬VS = ± 1 V –90 –70 dB

= 1 V –77 –70 dB

IN,cm

; Single-Ended Output 2.9 V p-p

; ⌬V

DIN+

OCM

= 1 V –65 dB

OUT,dm

= V

= V

DIN–

= 0 V –5 ± 1+5mV

OCM

= 2.5 ± 1 V –70 dB
= 2.5 ± 1 V 0.9968 1 1.0032 V/V

. See TPCs 13 and 14 for more information.

L,dm

REV. E

–3–

AD8138

ABSOLUTE MAXIMUM RATINGS

1

Supply Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ± 5.5 V

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ± V

V

OCM

Internal Power Dissipation . . . . . . . . . . . . . . . . . . . . 550 mW

2

(SOIC) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 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 those listed in the operational section
of this specification is not implied. Exposure to Absolute Maximum Ratings for
extended periods may affect device reliability.

2

Thermal resistance measured on SEMI standard four-layer board.

= 499⍀

R

F

RG = 499⍀

49.9⍀
R

G

24.9⍀

= 499⍀

AD8138

RF = 499⍀

R

= 499⍀

L,dm

Figure 1. Basic Test Circuit

PIN CONFIGURATION

1

–IN

V

2

OCM

V+

3

4

+OUT

NC = NO CONNECT

AD8138

+IN

8

NC

7

V–

6

–OUT

5

PIN FUNCTION DESCRIPTIONS

Pin No. Mnemonic Function

1 –IN Negative Input Summing Node

2V

OCM

Voltage applied to this pin sets the
common-mode output voltage with a
ratio of 1:1. For example, 1 V dc on

will set the dc bias level on +OUT

V

OCM

and –OUT to 1 V.

3V+ Positive Supply Voltage

4 +OUT Positive Output. Note that the voltage at

–D

is inverted at +OUT. (See Figure 2.)

IN

5 –OUT Negative Output. Note that the voltage

at +D

is inverted at –OUT. (See

IN

Figure 2.)

6V–Negative Supply Voltage

7NC No Connect

8 +IN Positive Input Summing Node

ORDERING GUIDE

Temperature Package Package Branding

Model Range Description Option Information

AD8138AR –40∞C to +85∞C 8-Lead SOIC R-8
AD8138AR-REEL –40∞C to +85∞C 8-Lead SOIC 13" Tape and Reel
AD8138AR-REEL7 –40∞C to +85∞C 8-Lead SOIC 7" Tape and Reel
AD8138ARM –40∞C to +85∞C 8-Lead MSOP RM-8 HBA
AD8138ARM-REEL –40∞C to +85∞C 8-Lead MSOP 13" Tape and Reel HBA
AD8138ARM-REEL7 –40∞C to +85∞C 8-Lead MSOP 7" Tape and Reel HBA
AD8138-EVAL Evaluation Board

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. 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.

REV. E–4–

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

TPC 1. Small Signal Frequency
Response

6

3

0

GAIN – dB

–3

–6

VS = +5V

VS = +5V

VS = ⴞ5V

VS = ⴞ5V

VIN = 0.2V p-p

= 0pF

C

F

VIN = 2V p-p

= 0pF

C

F

1000

= 499 V, TA = 25ⴗC; refer to Figure 1 for test setup.

L,dm

6

3

0

GAIN – dB

–3

–6

–9

1

10 100

FREQUENCY – MHz

CF = 0pF

CF = 1pF

VS = ⴞ5V

= 0.2V p-p

V

IN

1000

TPC 2. Small Signal Frequency
Response

6

3

0

GAIN – dB

–3

–6

CF = 1pF

VIN = 2V p-p

= ⴞ5V

V

S

CF = 0pF

0.5
VS = ⴞ5V

= 0.2V p-p

V

IN

0.3

0.1

GAIN – dB

–0.1

–0.3

–0.5

1

10 100

FREQUENCY – MHz

TPC 3. 0.1 dB Flatness vs.
Frequency

30

G = 10, RF = 4.99k⍀

20

G = 5, RF = 2.49k⍀

10

G = 2, RF = 1k⍀

GAIN – dB

G = 1, RF = 499⍀

0

CF = 0pF

CF = 1pF

VS = ⴞ5V

= 0pF

C

F

V

,dm

OUT

= 499⍀

R

G

= 0.2V p-p

–9

1

10 100

FREQUENCY – MHz

TPC 4. Large Signal Frequency
Response

–50

V

= 2V p-p

,dm

OUT

= 800⍀

R

L

–60

–70

HD2(VS = +5V)

–80

–90

DISTORTION – dBc

–100

–110

–120

HD3(VS = ⴞ5V)

010 7020 30 40 50 60

FUNDAMENTAL FREQUENCY – MHz

HD2(VS = ⴞ5V)

HD3(VS = +5V)

TPC 7. Harmonic Distortion vs.
Frequency

1000

–9

1

10 100

FREQUENCY – MHz

TPC 5. Large Signal Frequency
Response

–40

V

= 4V p-p

,dm

OUT

= 800⍀

R

L

–50

–60

–70

–80

DISTORTION – dBc

–90

–100

–110

HD3(VS = +5V)

HD2(VS = +5V)

HD2(VS = ⴞ5V)

HD3(VS = ⴞ5V)

010 7020 30 40 50 60

FUNDAMENTAL FREQUENCY – MHz

TPC 8. Harmonic Distortion vs.
Frequency

1000

–10

1

10 100

FREQUENCY – MHz

TPC 6. Small Signal Frequency
Response for Various Gains

–30

V

= 2V p-p

,dm

OUT

= 800⍀

R

L

–40

= 20MHz

F

O

–50

–60

–70

DISTORTION – dBc

–80

–90

–100

–4 –3 3

HD3(VS = +5)

HD3(VS = ⴞ5)

HD2(VS = ⴞ5)

–2 –1 0 1 2

V

OCM

HD2(VS = +5)

DC OUTPUT – V

TPC 9. Harmonic Distortion vs.
V

OCM

1000

4

REV. E

–5–