ANALOG DEVICES AD8131 Service Manual
Low Cost, High Speed
–
www.BDTIC.com/ADI
FEATURES
High speed
400 MHz, −3 dB full power bandwidth
2000 V/μs slew rate
Fixed gain of 2 with no external components
Internal common-mode feedback to improve gain and phase
balance: −60
Separate input to set the common-mode output voltage
Low distortion: 68 dB SFDR @ 5 MHz 200 Ω load
Power supply range +2.7 V to ±5 V
APPLICATIONS
Video line driver
Digital line driver
Low power differential ADC driver
Differential in/out level shifting
Single-ended input to differential output driver
GENERAL DESCRIPTION
The AD8131 is a differential or single-ended input to
differential output driver requiring no external components for
a fixed gain of 2. The AD8131 is a major advancement over op
amps for driving signals over long lines or for driving
differential input ADCs. The AD8131 has a unique internal
feedback feature that provides output gain and phase matching
that are balanced to −60 dB at 10 MHz, reducing radiated EMI
and suppressing harmonics. Manufactured on the Analog
Devices, Inc. next generation XFCB bipolar process, the
AD8131 has a −3 dB bandwidth of 400 MHz and delivers a
differential signal with very low harmonic distortion.
The AD8131 is a differential driver for the transmission of
h-speed signals over low-cost twisted pair or coax cables.
hig
The AD8131 can be used for either analog or digital video
signals or for other high-speed data transmission. The AD8131
driver is capable of driving either Cat3 or Cat5 twisted pair or
coax with minimal line attenuation. The AD8131 has
considerable cost and performance improvements over discrete
line driver solutions.
The AD8131 can replace transformers in a variety of applications,
p
reserving low frequency and dc information. The AD8131 does
not have the susceptibility to magnetic interference and hysteresis
of transformers. It is smaller, easier to work with, and has the high
reliability associated with ICs.
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 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.
dB @ 10 MHz
Differential Driver
AD8131
FUNCTIONAL BLOCK DIAGRAM
1
–D
IN
750Ω 750Ω
2
V
OCM
3
V+
1.5kΩ 1.5kΩ
45
+OUT
AD8131
NC = NO CONNECT
Figure 1.
20
= 2V p-p
ΔV
OUT, dm
/ΔV
ΔV
OUT, cm
–30
–40
–50
VS = +5V
–60
BALANCE ERROR (dB)
–70
V
= ±5V
S
–80
1 10 100 1000
Figure 2. Output Balance Error vs. Frequency
OUT, dm
FREQUENCY (MHz)
The AD8131’s differential output also helps balance the input
for differential ADCs, optimizing the distortion performance of
the ADCs. 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 with dual supply
signals. Fast overload recovery preserves sampling accuracy.
The AD8131 is available in both SOIC and MSOP packages for
o
peration over −40°C to +125°C.
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 ©2005 Analog Devices, Inc. All rights reserved.
+D
8
IN
7
NC
6
V–
–OUT
01072-001
01072-002
AD8131
www.BDTIC.com/ADI
TABLE OF CONTENTS
Specifications..................................................................................... 3
±D
to ±OUT Specifications...................................................... 3
IN
V
to ±OUT Specifications..................................................... 4
OCM
±D
to ±OUT Specifications...................................................... 5
IN
V
to ±OUT Specifications..................................................... 6
OCM
Absolute Maximum Ratings............................................................ 7
ESD Caution.................................................................................. 7
Pin Configuration and Function Descriptions............................. 8
Typical Performance Characteristics............................................. 9
Operational Description................................................................ 15
Theory of Operation ...................................................................... 16
Analyzing an Application Circuit.............................................16
Closed-Loop Gain...................................................................... 16
Estimating the Output Noise Voltage...................................... 16
Calculating the Input Impedance of an
Application Circuit..................................................................... 16
Input Common-Mode Voltage Range in
Single-Supply Applications .......................................................17
Setting the Output Common-Mode Voltage.......................... 17
Driving a Capacitive Load......................................................... 17
Applications..................................................................................... 18
Twisted-Pair Line Driver........................................................... 18
3 V Supply Differential A-to-D Driver.................................... 18
Unity-Gain, Single-Ended-to-Differential Driver ................. 19
Outline Dimensions .......................................................................20
Ordering Guide .......................................................................... 20
REVISION HISTORY
6/05—Rev. A to Rev. B
Updated Format..................................................................Universal
Changed Upper Operating Limit.....................................Universal
Changes to Ordering Guide.......................................................... 20
Rev. B | Page 2 of 20
AD8131
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SPECIFICATIONS
±DIN TO ±OUT SPECIFICATIONS
25°C, VS = ±5 V, V
descriptions. All specifications refer to single-ended input and differential outputs, unless otherwise noted.
Table 1.
Parameter Conditions Min Typ Max Unit
DYNAMIC PERFORMANCE
−3 dB Large Signal Bandwidth V
−3 dB Small Signal Bandwidth V
Bandwidth for 0.1 dB Flatness V
Slew Rate V
Settling Time 0.1%, V
Overdrive Recovery Time VIN = 5 V to 0 V Step 5 ns
NOISE/HARMONIC PERFORMANCE
Second Harmonic V
V
V
V
Third Harmonic V
V
V
V
IMD 20 MHz, R
IP3 20 MHz, R
Voltage Noise (RTO) f = 20 MHz 25 nV/√Hz
Differential Gain Error NTSC, R
Differential Phase Error NTSC, R
INPUT CHARACTERISTICS
Input Resistance Single-ended input 1.125 kΩ
Differential input 1.5 kΩ
Input Capacitance 1 pF
Input Common-Mode Voltage −7.0 to +5.0 V
CMRR ΔV
OUTPUT CHARACTERISTICS
Offset Voltage (RTO) V
T
V
T
Output Voltage Swing Maximum ΔV
Linear Output Current 60 mA
Gain ΔV
Output Balance Error ΔV
= 0 V, G = 2, R
OCM
= 200 Ω, unless otherwise noted. Refer to Figure 5 and Figure 39 for test setup and label
L, dm
= 2 V p-p 400 MHz
OUT
= 0.2 V p-p 320 MHz
OUT
= 0.2 V p-p 85 MHz
OUT
= 2 V p-p, 10% to 90% 2000 V/μs
OUT
= 2 V p-p 14 ns
OUT
= 2 V p-p, 5 MHz, R
OUT
= 2 V p-p, 20 MHz, R
OUT
= 2 V p-p, 5 MHz, R
OUT
= 2 V p-p, 20 MHz, R
OUT
= 2 V p-p, 5 MHz, R
OUT
= 2 V p-p, 20 MHz, R
OUT
= 2 V p-p, 5 MHz, R
OUT
= 2 V p-p, 20 MHz, R
OUT
= 800 Ω −54 dBc
L, dm
= 800 Ω 30 dBm
L, dm
= 150 Ω 0.01 %
L, dm
= 150 Ω 0.06 degrees
L, dm
/ΔV
OUT, dm
= V
OS, dm
to T
MIN
= float ±4 mV
OCM
to T
MIN
OUT, dm
OUT, cm
; ΔV
IN, cm
; V
OUT, dm
DIN+
variation ±8 μV/°C
MAX
variation ±10 μV/°C
MAX
; single-ended output −3.6 to +3.6 V
OUT
/ΔV
; ΔV
IN, dm
/ΔV
OUT, dm
; ΔV
= 200 Ω −68 dBc
L, dm
= 200 Ω −63 dBc
L, dm
= 800 Ω −95 dBc
L, dm
= 800 Ω −79 dBc
L, dm
= 200 Ω −94 dBc
L, dm
= 200 Ω −70 dBc
L, dm
= 800 Ω −101 dBc
L, dm
= 800 Ω −77 dBc
L, dm
= ±0.5 V −70 dB
IN, cm
= V
= V
DIN−
= ±0.5 V 1.97 2 2.03 V/V
IN, dm
OUT, dm
= 0 V ±2 ±7 mV
OCM
= 1 V −70 dB
Rev. B | Page 3 of 20
AD8131
www.BDTIC.com/ADI
V
TO ±OUT SPECIFICATIONS
OCM
25°C, VS = ±5 V, V
descriptions. All specifications refer to single-ended input and differential outputs, unless otherwise noted.
Table 2.
Parameter Conditions Min Typ Max Unit
DYNAMIC PERFORMANCE
−3 dB Bandwidth ΔV
Slew Rate V
DC PERFORMANCE
Input Voltage Range ±3.6 V
Input Resistance 120 kΩ
Input Offset Voltage V
V
Input Bias Current 0.5 μA
VOCM CMRR ΔV
Gain ΔV
POWER SUPPLY
Operating Range ±1.4 ± 5.5 V
Quiescent Current V
T
Power Supply Rejection Ratio ΔV
OPERATING TEMPERATURE RANGE −40 +125 °C
= 0 V, G = 2, R
OCM
= 200 Ω, unless otherwise noted. Refer to Figure 5 and Figure 39 for test setup and label
L, dm
= 600 mV 210 MHz
OCM
= −1 V to +1 V 500 V/μs
OCM
= V
OS, cm
= float ±2.5 mV
OCM
OUT, dm
OUT, cm
= V
DIN+
to T
MIN
OUT, dm
; V
= V
= V
OUT, cm
DIN+
DIN−
/ΔV
; ΔV
OCM
/ΔV
OCM
= V
DIN−
variation 25 μA/°C
MAX
= ±0.5 V −60 dB
OCM
; ΔV
= ±1 V 0.988 1 1.012 V/V
OCM
= 0 V 10.5 11.5 12.5 mA
OCM
= 0 V ±1.5 ±7 mV
OCM
/ΔVS; ΔVS = ±1 V −70 −56 dB
Rev. B | Page 4 of 20
AD8131
www.BDTIC.com/ADI
±DIN TO ±OUT SPECIFICATIONS
25°C, VS = 5 V, V
descriptions. All specifications refer to single-ended input and differential outputs, unless otherwise noted.
Table 3.
Parameter Conditions Min Typ Max Unit
DYNAMIC PERFORMANCE
−3 dB Large Signal Bandwidth V
−3 dB Small Signal Bandwidth V
Bandwidth for 0.1 dB Flatness V
Slew Rate V
Settling Time 0.1%, V
Overdrive Recovery Time VIN = 5 V to 0 V Step
NOISE/HARMONIC PERFORMANCE
Second Harmonic V
Third Harmonic V
IMD 20 MHz, R
IP3 20 MHz, R
Voltage Noise (RTO) f = 20 MHz
Differential Gain Error NTSC, R
Differential Phase Error NTSC, R
INPUT CHARACTERISTICS
Input Resistance Single-ended input
Input Capacitance
Input Common-Mode Voltage
CMRR ΔV
OUTPUT CHARACTERISTICS
Offset Voltage (RTO) V
Output Voltage Swing Maximum ΔV
Linear Output Current
Gain ΔV
Output Balance Error ΔV
= 2.5 V, G = 2, R
OCM
= 200 Ω, unless otherwise noted. Refer to Figure 5 and Figure 39 for test setup and label
L, dm
= 2 V p-p
OUT
= 0.2 V p-p
OUT
= 0.2 V p-p
OUT
= 2 V p-p, 10% to 90%
OUT
= 2 V p-p
OUT
385
285
65
1600
18
5
MHz
MHz
MHz
V/μs
ns
ns
= 2 V p-p, 5 MHz, R
OUT
= 2 V p-p, 20 MHz, R
V
OUT
= 2 V p-p, 5 MHz, R
V
OUT
= 2 V p-p, 20 MHz, R
V
OUT
= 2 V p-p, 5 MHz, R
OUT
= 2 V p-p, 20 MHz, R
V
OUT
= 2 V p-p, 5 MHz, R
V
OUT
= 2 V p-p, 20 MHz, R
V
OUT
= 800 Ω
L, dm
= 800 Ω
L, dm
= 150 Ω
L, dm
= 150 Ω
L, dm
L, dm
L, dm
L, dm
L, dm
L, dm
L, dm
L, dm
L, dm
= 200 Ω
= 200 Ω
= 800 Ω
= 800 Ω
= 200 Ω
= 200 Ω
= 800 Ω
= 800 Ω
−67
−56
−94
−77
−74
−67
−95
−74
−51
29
25
0.02
0.08
dBc
dBc
dBc
dBc
dBc
dBc
dBc
dBc
dBc
dBm
nV/√Hz
%
degrees
Differential input
/ΔV
; ΔV
OUT, dm
IN, cm
IN, cm
= ±0.5 V
1.125
1.5
1
−1.0 to +4.0
−70
kΩ
kΩ
pF
V
dB
= V
OS, dm
to T
T
MIN
= float
V
OCM
to T
T
MIN
OUT, dm
OUT, cm
OUT, dm
variation
MAX
variation
MAX
/ΔV
IN, dm
/ΔV
OUT, dm
; V
= V
DIN+
; single-ended output
OUT
; ΔV
; ΔV
= V
DIN−
= ±0.5 V 1.96 2 2.04 V/V
IN, dm
= 1 V
OUT, dm
OCM
= 2.5 V
±3 ±7 mV
±8
±4
±10
1.0 to 3.7
45
−62
μV/°C
mV
μV/°C
V
mA
dB
Rev. B | Page 5 of 20
AD8131
www.BDTIC.com/ADI
V
TO ±OUT SPECIFICATIONS
OCM
25°C, VS = 5 V, V
descriptions. All specifications refer to single-ended input and differential outputs, unless otherwise noted.
Table 4.
Parameter Conditions Min Typ Max Unit
DYNAMIC PERFORMANCE
−3 dB Bandwidth ΔV
Slew Rate V
DC PERFORMANCE
Input Voltage Range
Input Resistance
Input Offset Voltage V
Input Bias Current
V
CMRR ΔV
OCM
Gain ΔV
POWER SUPPLY
Operating Range
Quiescent Current V
Power Supply Rejection Ratio ΔV
OPERATING TEMPERATURE RANGE
= 2.5 V, G = 2, R
OCM
= 200 Ω, unless otherwise noted. Refer to Figure 5 and Figure 39 for test setup and label
L, dm
= 600 mV
OCM
= 1.5 V to 3.5 V
OCM
200
450
MHz
V/μs
V
OS, cm
OCM
= V
= float
OUT, cm
; V
DIN+
= V
DIN−
= V
OCM
= 2.5 V
/ΔV
; ΔV
OUT, dm
OUT, cm
/ΔV
OCM
OCM
= 2.5 V ±0.5 V
OCM
; ΔV
= 2.5 V ±1 V 0.985 1 1.015 V/V
OCM
1.0 to 3.7
30
±5 ±12 mV
±10
0.5
−60
V
kΩ
mV
μA
dB
T
= V
DIN+
DIN−
to T
MIN
MAX
/ΔVS; ΔVS = ±0.5 V
OUT, dm
2.7
= V
= 2.5 V 9.25 10.25 11.25 mA
OCM
variation
20
−70 −56 dB
−40 +125 °C
11 V
μA/°C
Rev. B | Page 6 of 20
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