ANALOG DEVICES AD8671 Service Manual

Precision, Very Low Noise, Low Input

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+

–

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www.BDTIC.com/ADI

FEATURES

Very low noise: 2.8 nV/√Hz, 77 nV p-p
Wide bandwidth: 10 MHz
Low input bias current: 12 nA max
Low offset voltage: 75 μV max
High open-loop gain: 120 dB min
Low supply current: 3 mA per amplifier
Dual-supply operation: ±5 V to ±15 V
Unity-gain stable
No phase reversal

APPLICATIONS

PLL filters
Filters for GPS
Instrumentation
Sensors and controls
Professional quality audio

GENERAL DESCRIPTION

The AD8671/AD8672/AD8674 are very high precision amplifiers
featuring very low noise, very low offset voltage and drift, low
input bias current, 10 MHz bandwidth, and low power
consumption. Outputs are stable with capacitive loads of over
1000 pF. Supply current is less than 3 mA per amplifier at 30 V.

The AD8671/AD8672/AD8674’s combination of ultralow noise,

h precision, speed, and stability is unmatched. The MSOP

hig
version of the AD8671/AD8672 requires only half the board
space of comparable amplifiers.

Bias Current Operational Amplifiers

AD8671/AD8672/AD8674

PIN CONFIGURATIONS

NC

1

AD8671

2

IN

TOP VIEW

IN

3

(Not to Scale)

V–

4

NC = NO CONNECT

Figure 1. 8-Lead SOIC_N (R-8)

1

OUT A

–IN A
+IN A

V–

AD8672

2

TOP VIEW

3

(Not to Scale)

4

Figure 3. 8-Lead SOIC-N (R-8)

OUT A

1
2

–IN A
+IN A

3

AD8674

V+

4

TOP VIEW

(Not to Scale)

+IN B

5
6

–IN B

OUT B

7

Figure 5. 14-Lead SOIC_N (R-14)

NC

8
7

V+
OUT

6

NC

5

03718-B-001

NC

1

AD8671

2

IN

TOP VIEW

IN

3

(Not to Scale)

V–

4

NC = NO CONNECT

NC

8
7

V+
OUT

6

NC

5

03718-B-002

Figure 2. 8-Lead MSOP (RM-8)

8
7
6
5

V+
OUT B
–IN B
+IN B

OUT A

1

V–

AD8672

2

TOP VIEW

3

(Not to Scale)

4

–IN A
+IN A

03718-B-003

8
7
6
5

V+
OUT B
–IN B
+IN B

03718-B-004

Figure 4. 8-Lead MSOP (RM-8)

14
13
12
11
10

9
8

OUT D
–IN D
+IN D
V–
+IN C
–IN C
OUT C

03718-B-005

OUT A

–IN A 2
+IN A

V+ 4
+IN B 5
–IN B

OUT B 7

1

3

AD8674

TOP VIEW

(Not to Scale)

6

14
13
12
11
10

9
8

OUT D
–IN D
+IN D
V–
+IN C
–IN C
OUT C

03718-B-006

Figure 6. 14-Lead TSSOP (RU-14)

Applications for these amplifiers include high quality PLL
f

ilters, precision filters, medical and analytical instrumentation,
precision power supply controls, ATE, data acquisition, and
precision controls as well as professional quality audio.

The AD8671/AD8672/AD8674 are specified over the extended
ind

ustrial temperature range (–40°C to +125°C).

The AD8671/AD8672 are available in the 8-lead SOIC and
8-lead MSO

P packages. The AD8674 is available in 14-lead

SOIC and 14-lead TSSOP packages.

Surface-mount devices in MSOP packages are available in tape

nd reel only.

a

Rev. C

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: [phone] www.analog.com
Fax: [phone] © 2005 Analog Devices, Inc. All rights reserved.

AD8671/AD8672/AD8674

www.BDTIC.com/ADI

TABLE OF CONTENTS

Specifications..................................................................................... 3

Total Noise vs. Source Resistance............................................. 11

Electrical Characteristics, ±5.0 V ............................................... 3

Electrical Characteristics, ±15 V................................................ 4

Absolute Maximum Ratings............................................................ 5

ESD CAUTION ............................................................................ 5

Typical Performance Characteristics ............................................. 6

Applications..................................................................................... 11

Unity-Gain Follower Applications ........................................... 11

Output Phase Reversal............................................................... 11

REVISION HISTORY

6/05—Rev. B to Rev. C

Changes to Figure 6...................................................................... 1

U

pdated Outline Dimensions................................................... 14

Changes to Ordering Guide...................................................... 16

4/04—Rev. A to Rev. B

Total Harmonic Distortion (THD) and Noise ....................... 12

Driving Capacitive Loads.......................................................... 12

GPS Receiver............................................................................... 13

Band-Pass Filter.......................................................................... 13

PLL Synthesizers and Loop Filters........................................... 13

Outline Dimensions ....................................................................... 14

Ordering Guide .......................................................................... 16

Changes to Figure 32.................................................................. 11

hanges to Figures 36, 37, and 38 ............................................ 12

C

1/04—Rev. 0 to Rev. A

Added AD8672 and AD8674 parts ..............................Universal

hanges to Specifications............................................................ 3

C

Deleted Figure 3............................................................................ 6

Changes to Figures 7, 8, and 9 .................................................... 6

Changes to Figure 37.................................................................. 12

Added new Figure 32 ................................................................. 10

Rev. C | Page 2 of 16

AD8671/AD8672/AD8674

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SPECIFICATIONS

ELECTRICAL CHARACTERISTICS, ±5.0 V

VS = ±5.0 V, VCM = 0 V, TA = 25°C, unless otherwise noted.

Table 1.

Parameter Symbol Conditions Min Typ Max Unit

INPUT CHARACTERISTICS

Offset Voltage V

OS

–40°C < TA < +125°C 30 125 μV
Offset Voltage Drift ∆VOS/∆T –40°C < TA < +125°C

AD8671 0.3 0.5 μV/°C
AD8672/AD8674 0.3 0.8 μV/°C

Input Bias Current I

B

+25°C < TA < +125°C –20 +5 +20 nA
–40°C < TA < +125°C –40 +8 +40 nA
Input Offset Current I

OS

+25°C < TA < +125°C –20 +6 +20 nA
–40°C < TA < +125°C –40 +8 +40 nA
Input Voltage Range –2.5 +2.5 V
Common-Mode Rejection Ratio CMRR VCM = –2.5 V to +2.5 V 100 120 dB
Large Signal Voltage Gain A
Input Capacitance, Common Mode C
Input Capacitance, Differential Mode C
Input Resistance, Common Mode R
Input Resistance, Differential Mode R

VO

INCM

INDM

IN

INDM

OUTPUT CHARACTERISTICS

Output Voltage High V
Output Voltage Low V
Output Voltage High V
Output Voltage Low V
Output Current I

OH

OL

OH

OL

OUT

POWER SUPPLY

Power Supply Rejection Ratio PSRR VS = ±4 V to ±18 V

AD8671/AD8672 110 130 dB
AD8674 106 115 dB

Supply Current/Amplifier I

SY

–40°C < TA < +125°C 4.2 mA
DYNAMIC PERFORMANCE

Slew Rate SR RL = 2 kΩ 4 V/μs
Settling Time t

S

To 0.01% (4 V step, G = 1) 5.1 μs
Gain Bandwidth Product GBP 10 MHz

NOISE PERFORMANCE

Peak-to-Peak Noise e
Voltage Noise Density e
Current Noise Density i

n p-p

n

n

Channel Separation

AD8672/AD8674 C

S

f = 10 kHz –105 dB

20 75 μV

–12 +3 +12 nA

–12 +6 +12 nA

RL = 2 kΩ, VO = –3 V to +3 V 1000 6000 V/mV

6.25 pF

7.5 pF

3.5 GΩ
15 MΩ

RL = 2 kΩ, –40°C to +125°C +3.8 +4.0 V
RL = 2 kΩ, –40°C to +125°C –3.9 –3.8 V
RL = 600 Ω +3.7 +3.9 V
RL = 600 Ω –3.8 –3.7 V
±10 mA

VO = 0 V 3 3.5 mA

To 0.1% (4 V step, G = 1) 1.4 μs

0.1 Hz to 10 Hz 77 100 nV p-p
f = 1 kHz 2.8 3.8 nV/√Hz
f = 1 kHz 0.3 pA/√Hz

f = 1 kHz –130 dB

Rev. C | Page 3 of 16

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ELECTRICAL CHARACTERISTICS, ±15 V

VS = ±15 V, VCM = 0 V, TA = 25°C, unless otherwise noted.

Table 2.

Parameter Symbol Conditions Min Typ Max Unit

INPUT CHARACTERISTICS

Offset Voltage V

OS

–40°C < TA < +125°C 30 125 μV
Offset Voltage Drift ∆VOS/∆T –40°C < TA < +125°C

AD8671 0.3 0.5 μV/°C
AD8672/AD8674 0.3 0.8 μV/°C

Input Bias Current I

B

+25°C < TA < +125°C –20 +5 +20 nA
–40°C < TA < +125°C –40 +8 +40 nA
Input Offset Current I

OS

+25°C < TA < +125°C –20 +6 +20 nA
–40°C < TA < +125°C –40 +8 +40 nA
Input Voltage Range –12 +12 V
Common-Mode Rejection Ratio CMRR VCM = –12 V to +12 V 100 120 dB
Large Signal Voltage Gain A
Input Capacitance, Common Mode C
Input Capacitance, Differential Mode C
Input Resistance, Common Mode R
Input Resistance, Differential Mode R

VO

INCM

INDM

IN

INDM

OUTPUT CHARACTERISTICS

Output Voltage High V
Output Voltage Low V
Output Voltage High V
Output Voltage Low V
Output Current I
Short Circuit Current I

OH

OL

OH

OL

OUT

SC

POWER SUPPLY

Power Supply Rejection Ratio PSRR VS = ±4 V to ±18 V

AD8671/AD8672 110 130 dB
AD8674 106 115 dB

Supply Current/Amplifier I

SY

–40°C <TA < +125°C 4.2 mA
DYNAMIC PERFORMANCE

Slew Rate SR RL = 2 kΩ 4 V/μs
Settling Time t

S

To 0.01% (10 V step, G = 1) 6.3 μs
Gain Bandwidth Product GBP 10 MHz

NOISE PERFORMANCE

Peak-to-Peak Noise e
Voltage Noise Density e
Current Noise Density i

n p-p

n

n

Channel Separation

AD8672/AD8674 C

S

f = 10 kHz –105 dB

20 75 μV

–12 +3 +12 nA

–12 +6 +12 nA

RL = 2 kΩ, VO = –10 V to +10 V 1000 6000 V/mV

6.25 pF

7.5 pF

3.5 GΩ
15 MΩ

RL = 2 kΩ, –40°C to +125°C +13.2 +13.8 V
RL = 2 kΩ, –40°C to +125°C –13.8 –13.2 V
RL = 600 Ω +11 +12.3 V
RL = 600 Ω –12.4 –11 V
±20 mA
±30 mA

VO = 0 V 3 3.5 mA

To 0.1% (10 V step, G = 1) 2.2 μs

0.1 Hz to 10 Hz 77 100 nV p-p
f = 1 kHz 2.8 3.8 nV/√Hz
f = 1 kHz 0.3 pA/√Hz

f = 1 kHz –130 dB

Rev. C | Page 4 of 16

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ABSOLUTE MAXIMUM RATINGS

Table 3.

Parameter Rating

Supply Voltage 36 V
Input Voltage VS– to VS+
Differential Input Voltage ±0.7 V
Output Short-Circuit Duration Indefinite
Storage Temperature Range

Operating Temperature Range

Junction Temperature Range

Lead Temperature Range (Soldering, 60 sec) 300°C

1

ESD 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 this product 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.

1

All Packages –65°C to +150°C

All Packages –40°C to +125°C

All Packages –65°C to +150°C

Absolute maximum ratings apply at 25°C, unless otherwise noted.

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.

Table 4. Package Characteristics

Package Type θ

8-Lead MSOP (RM) 190 44 °C/W
8-Lead SOIC_N (R) 158 43 °C/W
14-Lead SOIC_N (R) 120 36 °C/W
14-Lead TSSOP (RU) 180 35 °C/W

1

θJA is specified for the worst-case conditions, that is., θJA is specified for the

device soldered in circuit board for surface-mount packages.

1

JA

θ

JC

Unit

Rev. C | Page 5 of 16