Analog Devices AD8648 Service Manual

Low Cost, 24 MHz, Rail-to-Rail,

O

O

FEATURES

Low offset voltage: 2.5 mV max
Single-supply operation: 2.7 V to 5.5 V
Low noise: 6 nV/√Hz
Wide bandwidth: 24 MHz
Slew rate: 12 V/μs
High output current: 150 mA
No phase reversal
Low input bias current: 1 pA
Low supply current: 2 mA max
Unity-gain stable

APPLICATIONS

Barcode scanners
Battery-powered instrumentation
Multipole filters
Sensors
ASIC input or output amplifiers
Audio
Photodiode amplification

GENERAL DESCRIPTION

Quad Amplifiers

AD8648

PIN CONFIGURATIONS

1

1

UT A 14

2

2

–IN A

3

3

+IN A

+IN B

–IN B

UT B

V+

AD8648

AD8648

TOP VIEW

TOP VIEW

4

4

(Not to Scale)

(Not to Scale)

5

5

6

6

7

7

Figure 1. 14-Lead TSSOP (RU-14)

OUT A

1

1

2

2

–IN A

+IN A

3

3

AD8648

AD8648

TOP VIEW

TOP VIEW

V+

4

4

(Not to Scale)

(Not to Scale)

5

5 10

+IN B

–IN B

6

6 9

7

7 8

OUT B

Figure 2. 14-Lead SOIC (R-14)

14

14

13

13

12

12

11

11

10

14

13

13

12

12

11

11

10

10

9

9

8

8

9

8

OUT D

–IN D

+IN D

V–

+IN C

–IN C

OUT C

OUT D

–IN D

+IN D

V–

+IN C

–IN C

OUT C

05890-001

5890-002

The AD8648 is a quad, rail-to-rail, input and output, single­supply amplifier featuring low offset voltage, wide signal
bandwidth, and low input voltage and current noise.

The combination of 24 MHz bandwidth, low offset, low noise,
and very low input bias current makes these amplifiers useful in
a wide variety of applications. Filters, integrators, photodiode
amplifiers, and high impedance sensors all benefit from the
combination of performance features. AC applications benefit
from the wide bandwidth and low distortion. The AD8648
family offers high output drive capability, which is excellent for
audio line drivers and other low impedance applications.

Applications for the part include portable and low powered
instrumentation, audio amplification for portable devices,
portable phone headsets, bar code scanners, and multipole
filters. The ability to swing rail to rail at both the input and
output enables designers to buffer CMOS ADCs, DACs, ASICs,
and other wide output swing devices in single-supply systems.

Rev. 0

Information furnished by Analog Devices is believed to be accurate and reliable. However, no
responsibility is assumed by Anal og Devices for its use, nor for any infringements of patents or ot her
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] ©2006 Analog Devices, Inc. All rights reserved.

AD8648

TABLE OF CONTENTS

Features.............................................................................................. 1

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

Applications....................................................................................... 1

Pin Configurations ........................................................................... 1

General Description ......................................................................... 1

Revision History ............................................................................... 2

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

REVISION HISTORY

1/06—Rev 0: Initial Version

Thermal Resistance.......................................................................5

ESD Caution...................................................................................5

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

Outline Dimensions....................................................................... 12

Ordering Guide .......................................................................... 12

Rev. 0 | Page 2 of 12

AD8648

SPECIFICATIONS

VDD = 5.0 V, VCM = VDD/2, TA = 25oC, unless otherwise noted.

Table 1.

Parameter Symbol Conditions Min Typ Max Unit

INPUT CHARACTERISTICS

Offset Voltage V

OS

−40°C < TA < +125°C 3.2 mV
Offset Voltage Drift ΔVOS/ΔT −40°C < TA < +125°C 2.0 7.5 μV/°C
Input Bias Current I

B

−40°C < TA < +85°C 50 pA

−40°C < TA < +125°C 550 pA
Input Offset Current I

OS

−40°C < TA < +85°C 50 pA

−40°C < TA < +125°C 250 pA
Input Voltage Range V

CM

Common-Mode Rejection Ratio CMRR VCM = 0 V to 5.0 V 67 84 dB
Large-Signal Voltage Gain AVO R
Input Capacitance C
C

DIFF

CM

OUTPUT CHARACTERISTICS

Output Voltage High V

OH

I

−40°C < TA < +125°C 4.70 V
Output Voltage Low V

OL

I

−40°C < TA < +125°C 200 mV
Short-Circuit Output Current I
Closed-Loop Output Impedance Z

SC

OUT

POWER SUPPLY

Power Supply Rejection Ratio PSRR VDD = 2.7 V to 5.5 V 63 80 dB
Supply Current per Amplifier ISY 1.8 2.0 mA

−40°C < TA < +125°C 2.5 mA

DYNAMIC PERFORMANCE

Slew Rate SR RL = 2 kΩ 12 V/μs
Settling Time ts To 0.01% 0.5 μs
Gain Bandwidth Product GBP 24 MHz
Phase Margin Φ

M

NOISE PERFORMANCE

Peak-to-Peak Noise en p-p 0.1 Hz to 10 Hz 2.4 μV
Voltage Noise Density e

n

f = 10 kHz 6 nV/√Hz
Channel Separation CS f = 10 kHz −115 dB
f = 100 kHz −110 dB

VCM = 0 V to 5 V 0.7 2.5 mV

0.2 1 pA

0.1 0.5 pA

0 5 V

= 2 kΩ, VO = 0.5 V to 4.5 V 160 700 V/mV

L

2.5 pF

6.7 pF

I

= 1 mA 4.98 4.99 V

OUT

= 10 mA 4.87 4.92 V

OUT

I

= 1 mA 8.4 20 mV

OUT

= 10 mA 78 145 mV

OUT

±150 mA

At 1 MHz, AV = 1 3 Ω

74 Degrees

f = 1 kHz 8 nV/√Hz

Rev. 0 | Page 3 of 12

AD8648

VDD = 2.7 V, VCM = VDD/2, TA = 25oC, unless otherwise noted.

Table 2.

Parameter Symbol Conditions Min Typ Max Unit

INPUT CHARACTERISTICS

Offset Voltage V

OS

−40°C < TA < +125°C 3.2 mV
Offset Voltage Drift ΔVOS/ΔT −40°C < TA < +125°C 1.8 7.0 μV/°C
Input Bias Current I

B

−40°C < TA < +85°C 50 pA

−40°C < TA < +125°C 550 pA
Input Offset Current I

OS

−40°C < TA < +85°C 50 pA

−40°C < TA < +125°C 250 pA
Input Voltage Range V

CM

Common-Mode Rejection Ratio CMRR VCM = 0 V to 2.7 V 62 79 dB
Large-Signal Voltage Gain AVO R
Input Capacitance C
C

DIFF

CM

OUTPUT CHARACTERISTICS

Output Voltage High V

OH

−40°C < TA < +125°C 2.60 V
Output Voltage Low V

OL

−40°C < TA < +125°C 30 mV
Short-Circuit Output Current I
Closed-Loop Output Impedance Z

SC

OUT

POWER SUPPLY

Power Supply Rejection Ratio PSRR VDD = 2.7 V to 5.5 V 63 80 dB
Supply Current per Amplifier ISY 1.7 2.0 mA

−40°C < TA < +125°C 2.5 mA

DYNAMIC PERFORMANCE

Slew Rate SR RL = 2 kΩ 12 V/μs
Settling Time ts To 0.01% 0.3 μs
Gain Bandwidth Product GBP 22 MHz
Phase Margin Φ

M

NOISE PERFORMANCE

Peak-to-Peak Noise en p-p 0.1 Hz to 10 Hz 2.1 μV
Voltage Noise Density e

n

f = 10 kHz 6 nV/√Hz
Channel Separation CS f = 10 kHz −115 dB
f = 100 kHz −110 dB

VCM = 0 V to 2.7 V 0.7 2.5 mV

0.2 1 pA

0.1 0.5 pA

0 2.7 V

= 2 kΩ, VO = 0.5 V to 2.2 V 60 130 V/mV

L

2.5 pF

7.8 pF

I

= 1 mA 2.65 2.69 V

OUT

I

= 1 mA 11 25 mV

OUT

±50 mA

At 1 MHz, AV = 1 3 Ω

52 Degrees

f = 1 kHz 8 nV/√Hz

Rev. 0 | Page 4 of 12

AD8648

ABSOLUTE MAXIMUM RATINGS

Table 3.

Parameter Rating

Supply Voltage 6 V
Input Voltage GND to V
Differential Input Voltage ±3 V
Output Short Circuit to GND Indefinite
Storage Temperature Range −65°C to +150°C
Operating Temperature Range −40°C to +125°C
Lead Temperature (Soldering, 60 sec) 300°C
Junction Temperature 150°C

DD

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.

THERMAL RESISTANCE

θJA is specified for the worst-case conditions, that is, a device
soldered in a circuit board for surface-mount packages.

Table 4. Thermal Resistance

Package Type θJA θ

14-Lead SOIC (R) 120 36 °C/W
14-Lead TSSOP (RU) 180 35 °C/W

Unit

JC

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.

Rev. 0 | Page 5 of 12

AD8648

A

T

T

A
G

TYPICAL PERFORMANCE CHARACTERISTICS

140

120

100

VDD=5V

=2.5V

V

CM

T = 25°C
1400 AMPLIFIERS

1000

VDD=2.7VTO5V

100

80

60

40

NUMBER OF AMPLIF IERS

20

0
–2.0 –1.5 –1.0 –0.5 0 0.5 1.0 1.5 2.0

INPUT OFFSET VOLTAGE (mV)

Figure 3. Input Offset Voltage Distribution

MPLIFIERS

NUMBER OF

30

25

20

15

10

5

VDD=5V
V

=2.5V

CM

–40°C < T

< +125°C

A

10

BIAS CURRENT (pA)

1

INPU

0.1

25 45 65 85 105 125

05890-003

TE MP ERA TURE (° C)

05890-006

Figure 6. Input Bias Current vs. Temperature

1000

VDD= 5V
T = 25°C

VDD–V

E(mV)

100

10

TURATION VOLTA
S

1

OUTPU

OH

SOURCING

V

OL

SINKING

0

01234567

Figure 4. V

2500

2000

1500

1000

500

0

–500

–1000

INPUTOFFSETVOLTAGE(µV)

–1500

–2000

–2500

01234

TCVOS (µV/°C)

Drift (TCVOS) Distribution

OS

INPUT COMMON-MODE VOLTAGE (V)

VDD=5V

=25°C

T

A

Figure 5. Input Offset Voltage vs. Input Common-Mode Voltage

05890-004

5

05890-005

Rev. 0 | Page 6 of 12

0.1

0.001 0.01 0.1 1 10 100

LOAD CURRENT (mA)

Figure 7. Output Saturation Voltage vs. Load Current

25

20

15

VDD– V

OH

SOURCING

10

V

OL

SINKING

5

OUTPUT SATURAT ION VOL TAGE (mV)

0

–40 –20 0 20 40 60 80 100 120

TEMPERATURE ( °C)

VDD= 5V
I

OUT

Figure 8. Output Saturation Voltage vs. Temperature

= 1mA

05890-007

05890-008

AD8648

(

80

60

PHASE

40

VDD = 5V
R
CL = 10pF

L

= 1k

0

Ω

45

90

100

VDD = 5V
T

= 25°C

A

80

20

0

OPEN-LOOP GAIN (dB)

–20

–40

10k 100k 1M 10M 100M

FREQUENCY (Hz)

GAIN

Ф

= 74°

M

Figure 9. Open-Loop Gain and Phase vs. Frequency

5.0

4.5

4.0

3.5

3.0

2.5

2.0

1.5

OUTPUT SWING (V p-p)

1.0

0.5

0
100k 1M 10M

FREQUENCY (Hz)

VDD = 5V

= 4.9V p-p

V

IN

= 1

A

V

= 10kΩ

R

L

= 25°C

T

A

Figure 10. Maximum Output Swing vs. Frequency

135

180

225

270

OPEN-LOOP PHASE SHIFT (Degrees)

05890-010

60

CMRR (dB)

40

20

1k 10M

05890-009

10k 100k 1M

FREQUENCY (Hz)

05890-012

Figure 12. Common-Mode Rejection Ratio vs. Frequency

100

80

60

PSRR (dB)

40

20

PSRR+

PSRR–

0

1k 10M

10k 100k 1M

FREQUENCY (Hz)

VDD = 5V
T

= 25°C

A

05890-013

Figure 13. Power Supply Rejection Ratio vs. Frequency

1000

VDD = 5V
T

= 25°C

A

100

Ω)

10

OUT

Z

1

0.1
1K 10K 100K 1M 10M 100M

AV = 100

= 10

A

V

AV = 1

FREQUENCY (Hz)

Figure 11. Closed-Loop Output Impedance vs. Frequency

05890-011

1000

100

10

VOLTAGE NOISE DENSI TY (nV/ √Hz)

1

10 10k

100 1k

FREQUENCY (Hz)

VDD = 2.7V TO 5V

= 25°C

T

A

Figure 14. Voltage Noise Density vs. Frequency

05890-014

Rev. 0 | Page 7 of 12

AD8648

0.1

VDD = 2.7V TO 5V

= 25°C

T

A

0.01

THD + NOISE (%)

VOLTAGE (1µV/DIV)

TIME (1s/DIV)

5890-015

Figure 15. 0.1 Hz to 10 Hz Voltage Noise

VDD = 5V
R

= 10kΩ

L

C

= 20pF

L

A

= 1

V

0.001

0.0001
10020 1k

FREQUENCY (Hz)

Figure 18. THD + Noise vs. Frequency

1

0.1

VDD = 5V

= 300mV rms

V

IN

BW = 80kHz

= 100kΩ

R

L

10k 20k

05890-018

0.01

THD + NOISE (%)

0.001

0.0001

SMALL-SIGNAL OVERSHOOT (%)

VDD = 5V

= 1

A

V

BW = 30kHz

= 100kΩ

R

L

f

= 1kHz

0.010.001 0.1

OUTPUT AMPLITUDE (V rms)

Figure 19. THD + Noise vs. Output Amplitude

70

VDD = 5V

= 10kΩ

R

L

= 25°C

T

60

A

50

40

OS+

30

20

10

OS–

1

05890-019

OUTPUT VOLTAGE (50mV/DIV)

TIME (40ns/DIV)

05890-016

Figure 16. Small-Signal Transient Response

VDD = 5V
R

= 100kΩ

L

C

= 20pF

L

A

= 1

V

OUTPUT VOLTAGE (500mV/DIV)

TIME (200n s/DIV)

Figure 17. Large-Signal Transient Response

05890-017

Rev. 0 | Page 8 of 12

0

10 1000

LOAD CAPACITANCE ( pF)

100

Figure 20. Small-Signal Overshoot vs. Load Capacitance

05890-020

AD8648

NUMBER OF AMPLIFIERS

160

140

120

100

VDD = 2.7V

= 1.35V

V

CM

T

= 25°C

A

1400 AMPLIFIERS

80

60

40

20

OUTPUT SAT URATION VO LTAGE (V)

1000

100

10

1

VDD = 2.7V
T

= 25°C

A

VDD– V

SOURCING

OH

V

OL

SINKING

0
–2.0 2.0

–1.5 –1.0 –0.5 0 0.5 1.0 1.5

INPUT OFFSET VOLTAGE (mV)

05890-021

Figure 21. Input Offset Voltage Distribution

30

25

20

15

10

NUMBER OF AMPLIFIERS

5

0

08

1234567

TCV

OS

Figure 22. V

Drift (TCVOS) Distribution

OS

(µV/°C)

VDD = 2.7V

= 1.35V

V

CM

–40°C < T

< +125° C

A

05890-022

0.1

0.001 101

Figure 24. Output Saturation Voltage vs. Load Current

25

20

15

10

5

OUTPUT SAT URATION VO LTAGE (V)

0

–40 120

–20 0 20 40 60 80 100

Figure 25. Output Saturation Voltage vs. Temperature

0.10.01

LOAD CURRENT (mA)

V

– V

DD

OH

SOURCING

TEMPERATURE (° C)

V

OL

SINKING

VDD = 2.7V

= 1mA

I

LOAD

5890-024

05890-025

2500

2000

1500

1000

500

0

–500

–1000

INPUT OFFSET VOLTAGE (µV)

–1500

–2000

–2500

03

0.5 1.0 1.5 2.0 2.5

INPUT COMMON-MODE VOLTAGE (V)

VDD = 2.7V

= 25°C

T

A

.0

05890-023

Figure 23. Input Offset Voltage vs. Input Common-Mode Voltage

80

60

40

20

0

OPEN-LOOP GAIN (dB)

–20

–40

10k 100M10M

Figure 26. Open-Loop Gain and Phase vs. Frequency

Rev. 0 | Page 9 of 12

100k 1M

FREQUENCY (Hz)

ФM = 52°

VDD = 2.7V

= 1kΩ

R

L

= 10pF

C

L

0

45

90

135

180

225

270

OPEN-LOOP PHASE SHIFT (Degrees)

5890-026

AD8648

3.0

2.5

2.0

1.5

1.0

OUTPUT SWING (V p-p)

0.5

0

100k 1M

FREQUENCY (Hz)

Figure 27. Maximum Output Swing vs. Frequency

1000

= 2.7V

V

DD

= 25°C

T

A

100

VDD = 2.7V

= 2.6V p-p

V

IN

A

= 1

V

= 10kΩ

R

L

= 25°C

T

A

10M

5890-027

100

PSRR+

80

60

PSRR–

PSRR (dB)

40

20

0

1k 10M

10k 100k 1M

FREQUENCY (Hz)

Figure 30. Power Supply Rejection Ratio vs. Frequency

VDD = 2.7V

= 25°C

T

A

VDD = 2.7V
R

= 10kΩ

L

C

= 20pF

L

A

= 1

V

05890-030

A

= 100

V

(Ω)

10

OUT

Z

1

0.1
1k 100M

10k 100k 1M 10M

A

= 10

V

AV = 1

FREQUENCY (Hz)

Figure 28. Closed-Loop Output Impedance vs. Frequency

100

80

60

CMRR (dB)

40

VDD = 2.7V
T

= 25°C

A

OUTPUT VOLTAGE (50mV/DIV)

05890-028

TIME (40n s/DIV)

05890-031

Figure 31. Small-Signal Transient Response

VDD = 2.7V
R

= 10kΩ

L

C

= 20pF

L

A

= 1

V

OUTPUT VOLTAGE (500mV/DIV)

20

1k 10M

10k 100k 1M

FREQUENCY (Hz)

Figure 29. Common-Mode Rejection Ratio vs. Frequency

05890-029

Rev. 0 | Page 10 of 12

TIME (1µs/DIV)

Figure 32. Large-Signal Transient Response

05890-032

AD8648

50

40

VDD = 2.7V

= 10kΩ

R

L

T

= 25°C

A

2.5

2.0

TA = 25°C

30

20

10

SMALL-SIGNAL OVERSHOOT (%)

0

1 1000

10 100

LOAD CAPACITANCE ( pF)

OS+

OS–

Figure 33. Small-Signal Overshoot vs. Load Capacitance

4.0

3.5

3.0

2.5

2.0

1.5

1.0

V

VDD = 2.7V

VDD = 5.0V

OUT

= VDD/2

1.5

1.0

0.5

SUPPLY CURRENT PER AMPLIFIER (mA)

0

05

0.5 1.0 1.5 2.0 2. 5 3.0 3.5 4.0 4. 5

05890-033

SUPPLY VOLTAGE (V)

.0

05890-035

Figure 35. Supply Current per Amplifier vs. Supply Voltage

0.5

SUPPLY CURRENT PER AMPLIFIER (mA)

0

–40 120

–20 0 20 40 60 80 100

TEMPERATURE (° C)

05890-034

Figure 34. Supply Current per Amplifier vs. Temperature

Rev. 0 | Page 11 of 12

AD8648

OUTLINE DIMENSIONS

5.10

5.00

4.90

4.50

4.40

4.30

PIN 1

1.05

1.00

0.80

0.15

0.05

4.00 (0.1575)

3.80 (0.1496)

0.25 (0.0098)

0.10 (0.0039)

COPLANARITY

0.10

14

0.65

BSC

0.30

0.19

COMPLIANT TO JEDEC STANDARDS MO-153-AB-1

8

6.40

BSC

71

1.20
MAX

SEATING
PLANE

0.20

0.09

COPLANARITY

0.10

8°
0°

Figure 36. 14-Lead Thin Shrink Small Outline Package [TSSOP]

(RU-14)

Dimensions shown in millimeters

8.75 (0.3445)

8.55 (0.3366)

14

1

1.27 (0.0500)
BSC

0.51 (0.0201)

0.31 (0.0122)

8

6.20 (0.2441)

7

5.80 (0.2283)

1.75 (0.0689)

1.35 (0.0531)

SEATING
PLANE

0.25 (0.0098)

0.17 (0.0067)

0.50 (0.0197)

0.25 (0.0098)

8°
0°

1.27 (0.0500)

0.40 (0.0157)

0.75

0.60

0.45

× 45°

COMPLIANT TO JEDEC STANDARDS MS-012-AB

CONTROLLING DIMENSIONS ARE IN MILLIMETERS; INCH DIMENSIONS
(IN PARENTHESES) ARE ROUNDED-OFF MILLIMETER EQUIVALENTS FOR
REFERENCE ONLY AND ARE NOT APPROPRIATE FOR USE IN DESIGN.

Figure 37. 14-Lead Standard Small Outline Package [SOIC_N]

Narrow Body (R-14)

Dimensions shown in millimeters and (inches)

ORDERING GUIDE

Model Temperature Range Package Description Package Option

AD8648ARZ
AD8648ARZ-REEL
AD8648ARZ-REEL7
AD8648ARUZ
AD8648ARUZ-REEL

1

Z = Pb-free part.

©2006 Analog Devices, Inc. All rights reserved. Trademarks and
registered trademarks are the property of their respective owners.
D05890–0–1/06(0)

1

1

1

1

1

−40°C to +125°C 14-Lead SOIC_N R-14

−40°C to +125°C 14-Lead SOIC_N R-14

−40°C to +125°C 14-Lead SOIC_N R-14

−40°C to +125°C 14-Lead TSSOP RU-14

−40°C to +125°C 14-Lead TSSOP RU-14

Rev. 0 | Page 12 of 12