ANALOG DEVICES AD8337 Service Manual

General-Purpose, Low Cost,

V

V

www.BDTIC.com/ADI

FEATURES

Low noise

Voltage noise = 2.2 nV/√Hz

Current noise = 4.8 pA/√Hz (positive input)
Wide bandwidth (−3 dB) = 280 MHz
Nominal gain range: 0 dB to 24 dB (preamp gain = 6 dB)
Gain scaling: 19.7 dB/V
DC-coupled
Single-ended input and output
High speed uncommitted op amp input
Supplies: +5 V, ±2.5 V, or ±5 V
Low power: 78 mW with ±2.5 V supplies

APPLICATIONS

Gain trim
PET scanners
High performance AGC systems
I/Q signal processing
Video
Industrial and medical ultrasound
Radar receivers

DC-Coupled VGA

FUNCTIONAL BLOCK DIAGRAM

AD8337

GAIN CONTROL

7

INTERFACE

PREAMP

INPP

INPN

VCOM

(PrA)

3

+

–

4

2

5

PRAO

EIGHT SECT IONS

6

VNEG

Figure 1.

POS

8

8

AD8337

18dB

OUTGAIN

1

05575-001

GENERAL DESCRIPTION

The AD8337 is a low noise, single-ended, linear-in-dB, general­purpose variable gain amplifier (VGA) usable at frequencies
from dc to 100 MHz; the −3 dB bandwidth is 280 MHz.
Excellent bandwidth uniformity across the entire gain range
and low output-referred noise makes the AD8337 ideal for
gain trim applications and for driving high speed analog-to­digital converters (ADCs).

Excellent dc characteristics combined with high speed make the
AD8337 particularly suited for industrial ultrasound, PET
scanners, and video applications. Dual-supply operation enables
gain control of negative-going pulses, such as those generated
by photodiodes or photomultiplier tubes.

The AD8337 uses the popular and versatile X-AMP® architecture,
exclusively from Analog Devices, Inc., with a gain range of 24 dB.
The gain control interface provides precise linear-in-dB scaling
of 19.7 dB/V, referenced to VCOM.

The AD8337 includes an uncommitted operational current­feedback preamplifier (PrA) that operates in inverting or
noninverting configurations. Using external resistors, the device
can be configured for gains of 6 dB or greater. The AD8337 is
characterized by a noninverting PrA gain of 2× using two external
100 Ω resistors. The attenuator has a range of 24 dB, and the
output amplifier has a fixed gain of 8× (18.06 dB). The lowest
nominal gain range is 0 dB to 24 dB and can be shifted up or down
by adjusting the preamp gain. Multiple AD8337 devices can be
connected in series for larger gain ranges, interstage filtering to
suppress noise and distortion, and nulling offset voltages.

The operating temperature range of the AD8337 is −40°C to
+85°C, and is available in an 8-lead, 3 mm × 3 mm LFCSP.

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] ©2005–2008 Analog Devices, Inc. All rights reserved.

AD8337

www.BDTIC.com/ADI

TABLE OF CONTENTS

Features .............................................................................................. 1

Applications ....................................................................................... 1 

Functional Block Diagram .............................................................. 1

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

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

Specifications ..................................................................................... 3

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

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

Pin Configuration and Function Descriptions ............................. 6

Typical Performance Characteristics ............................................. 7

Test Circuits ..................................................................................... 14

Theory of Operation ...................................................................... 18

Overview ...................................................................................... 18

Preamplifier ................................................................................. 18 

VGA .............................................................................................. 18

Gain Control ............................................................................... 18

Output Stage ................................................................................ 19

Attenuator .................................................................................... 19

Single-Supply Operation and AC Coupling ........................... 19

Noise ............................................................................................ 19

Applications Information .............................................................. 20

Preamplifier Connections ......................................................... 20

Driving Capacitive Loads .......................................................... 20

Gain Control Considerations ................................................... 21

Thermal Considerations ............................................................ 22

PSI (Ψ) ......................................................................................... 22

Board Layout ............................................................................... 22

Evaluation Boards ........................................................................... 23

Circuit Options ........................................................................... 24

Output Protection ...................................................................... 24

Measurement Setup.................................................................... 25

Board Layout Considerations ................................................... 25

Bill of Materials ........................................................................... 27

Outline Dimensions ....................................................................... 29

Ordering Guide .......................................................................... 29

REVISION HISTORY

9/08—Rev. B to Rev. C

Changes to Table 1 ............................................................................ 3

Added Exposed Pad Note to Figure 2 and Table 3 ....................... 6

Changes to Figure 49 ...................................................................... 14

Changes to Evaluation Boards Section ........................................ 23

Changes to Circuit Options Section ............................................. 24

Changes to Output Protection Section ........................................ 24

Changes to Measurement Setup Section ..................................... 25

Changes to Board Layout Considerations Section ..................... 25

Changes to Bill of Materials Section ............................................ 27

Updated Outline Dimensions, Changes to Ordering Guide .... 29

2/07—Rev. A to Rev. B

Changes to Figure 30, Figure 31, and Figure 32 ......................... 11

Changes to Single-Supply Operation and

AC Coupling Section ..................................................................... 19

Moved Noise Section to Page ........................................................ 19

Changes to Ordering Guide .......................................................... 24

6/06—Rev. 0 to Rev. A

Updated Format .................................................................. Universal

Changes to Table 3 ............................................................................. 6

Changes to Figure 22, Figure 25, and Figure 26 ......................... 10

Changes to Figure 39 and Figure 40............................................. 13

Changes to Figure 74 and Figure 75............................................. 23

Updated Outline Dimensions ....................................................... 25

Changes to Ordering Guide .......................................................... 25

9/05—Revision 0: Initial Version

Rev. C | Page 2 of 32

AD8337

www.BDTIC.com/ADI

SPECIFICATIONS

VS = ±2.5 V, TA = 25°C, PrA gain = +2, V
otherwise specified.

Table 1.

Parameter Conditions Min Typ Max Unit

GENERAL PARAMETERS

−3 dB Small Signal Bandwidth V

−3 dB Large Signal Bandwidth V
Slew Rate V
V
Input Voltage Noise f = 10 MHz 2.15 nV/√Hz
Input Current Noise f = 10 MHz 4.8 pA/√Hz
Noise Figure V
V
Output-Referred Noise V
V
Output Impedance DC to 10 MHz 1 Ω
Output Signal Range

Output Offset Voltage V

DYNAMIC PERFORMANCE

Harmonic Distortion V

HD2 f = 1 MHz −72 dBc
HD3 −66 dBc
HD2 f = 10 MHz −62 dBc
HD3 −63 dBc
HD2 f = 45 MHz −58 dBc

HD3 −56 dBc
Input 1 dB Compression Point V
V
Two-Tone Intermodulation Distortion (IMD3) V
V
V
V
Output Third-Order Intercept V
V
V
V
Overload Recovery V
Group Delay Variation 1 MHz < f < 100 MHz, full gain range ±1 ns

= GND, f = 10 MHz, CL = 5 pF, RL = 500 Ω, including a 20 Ω snubbing resistor, unless

COM

= 10 mV p-p 280 MHz

OUT

= 1 V p-p 100 MHz

OUT

= 2 V p-p 625 V/μs

OUT

= 1 V p-p 490 V/μs

OUT

= 0.7 V, RS = 50 Ω, unterminated 8.5 dB

GAIN

= 0.7 V, RS = 50 Ω, shunt terminated with 50 Ω 14 dB

GAIN

= 0.7 V (gain = 24 dB) 34 nV/√Hz

GAIN

= −0.7 V (gain = 0 dB) 21 nV/√Hz

GAIN

≥ 500 Ω, VS = ±2.5 V, +5 V

R

L

≥ 500 Ω, VS = ±5 V

R

L

= 0.7 V (gain = 24 dB) −25 ±5 +25 mV

GAIN

= 0 V, V

GAIN

= −0.7 V, f = 10 MHz (preamp limited) 8.2 dBm

GAIN

= +0.7 V, f = 10 MHz (VGA limited) −9.4 dBm

GAIN

= 0 V, V

GAIN

= 0 V, V

GAIN

= 0 V, V

GAIN

= 0 V, V

GAIN

= 0 V, V

GAIN

= 0 V, V

GAIN

= 0 V, V

GAIN

= 0 V, V

GAIN

= 0.75 V, VIN = 50 mV p-p to 500 mV p-p 50 ns

GAIN

= 1 V p-p

OUT

= 1 V p-p, f1 = 10 MHz, f2 = 11 MHz −71 dBc

OUT

= 1 V p-p, f1 = 45 MHz, f2 = 46 MHz −57 dBc

OUT

= 2 V p-p, f1 = 10 MHz, f2 = 11 MHz −58 dBc

OUT

= 2 V p-p, f1 = 45 MHz, f2 = 46 MHz −45 dBc

OUT

= 1 V p-p, f = 10 MHz 34 dBm

OUT

= 1 V p-p, f = 45 MHz 28 dBm

OUT

= 2 V p-p, f = 10 MHz 35 dBm

OUT

= 2 V p-p, f = 45 MHz 26 dBm

OUT

V

± 1.3

COM

V

± 2.4

COM

V
V

Rev. C | Page 3 of 32

AD8337

www.BDTIC.com/ADI

Parameter Conditions Min Typ Max Unit

DYNAMIC PERFORMANCE VS = ±5 V

Harmonic Distortion V

HD2 f = 1 MHz −85 dBc
HD3 −75 dBc
HD2 f = 10 MHz −90 dBc
HD3 −80 dBc
HD2 f = 35 MHz −75 dBc

HD3 −76 dBc
Input 1 dB Compression Point V
V
Two-Tone Intermodulation Distortion (IMD3) V
V
V
V
Output Third-Order Intercept V
V
V
V
Overload Recovery V

ACCURACY

Absolute Gain Error −0.7 V < V

−0.6 V < V

−0.5 V < V

0.5 V < V

0.6 V < V
GAIN CONTROL INTERFACE

Gain Scaling Factor −0.6 V < V
Gain Range 24 dB
Intercept V
Input Voltage (V

) Range No foldover −VS +VS V

GAIN

Input Impedance 70 MΩ
Bias Current −0.7 V < V
Response Time 24 dB gain change 200 ns

POWER SUPPLY

Supply Voltage V
VS = ±2.5 V

Quiescent Current Each supply (VPOS and VNEG) 10.5 15.5 23.5 mA

Power Dissipation No signal, VPOS to VNEG = 5 V 78 mW

PSRR V
VS = ±5 V

Quiescent Current Each supply (VPOS and VNEG) 13.5 18.5 25.5 mA

Power Dissipation No signal, VPOS to VNEG = 10 V 185 mW

PSRR V

= 0 V, V

GAIN

= −0.7 V, f = 10 MHz 14.5 dBm

GAIN

= +0.7 V, f = 10 MHz −1.7 dBm

GAIN

= 0 V, V

GAIN

= 0 V, V

GAIN

= 0 V, V

GAIN

= 0 V, V

GAIN

= 0 V, V

GAIN

= 0 V, V

GAIN

= 0 V, V

GAIN

= 0 V, V

GAIN

= 0.7 V, VIN = 0.1 V p-p to 1 V p-p 50 ns

GAIN

= 0 V 12.65 dB

GAIN

to V

POS

= 0.7 V, f = 1 MHz −40 dB

GAIN

= 0.7 V, f = 1 MHz −40 dB

GAIN

= 1 V p-p

OUT

= 1 V p-p, f1 = 10 MHz, f2 = 11 MHz −74 dBc

OUT

= 1 V p-p, f1 = 45 MHz, f2 = 46 MHz −60 dBc

OUT

= 2 V p-p, f1 = 10 MHz, f2 = 11 MHz −64 dBc

OUT

= 2 V p-p, f1 = 45 MHz, f2 = 46 MHz −49 dBc

OUT

= 1 V p-p, f = 10 MHz 35 dBm

OUT

= 1 V p-p, f = 45 MHz 28 dBm

OUT

= 2 V p-p, f = 10 MHz 36 dBm

OUT

= 2 V p-p, f = 45 MHz 28 dBm

OUT

< −0.6 V 0.7 to 3.5 dB

GAIN

< −0.5 V −1.25 ±0.35 +1.25 dB

GAIN

< +0.5 V −1.0 ±0.25 +1.0 dB

GAIN

< 0.6 V −1.25 ±0.35 +1.25 dB

GAIN

< 0.7 V −0.7 to −3.5 dB

GAIN

< +0.6 V 19.7 dB/V

GAIN

< +0.7 V 0.3 μA

GAIN

(dual- or single-supply operation) 4.5 5 10 V

NEG

Rev. C | Page 4 of 32

AD8337

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ABSOLUTE MAXIMUM RATINGS

Table 2.

Parameter Rating

Voltage

Supply Voltage (VPOS, VNEG) ±6 V
Input Voltage (INPx) VPOS, VNEG
GAIN Voltage VPOS, VNEG

Power Dissipation

(Exposed Pad Soldered to PCB)

Temperature

Operating Temperature Range −40°C to +85°C
Storage Temperature Range −65°C to +150°C
Lead Temperature (Soldering, 60 sec) 300°C

Thermal Data, 4-Layer JEDEC Board

No Air Flow Exposed Pad Soldered to PCB
θJA 75.4°C/W
θJB 47.5°C/W
θJC 17.9°C/W
ΨJT 2.2°C/W
ΨJB 46.2°C/W

866 mW

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.

ESD CAUTION

Rev. C | Page 5 of 32

AD8337

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PIN CONFIGURATION AND FUNCTION DESCRIPTIONS

VOUT

VCOM

INPP

INPN

NOTES

1. FOR BEST THERMAL PERFORMANCE, EXPOSED PAD
MUST BE SOLDERED TO PCB.

PIN 1

1

AD8337

2

TOP VIEW

3

(Not to Scale)

4

Figure 2. Pin Configuration

VPOS

8

7

GAIN

6

VNEG

5

PRAO

05575-002

Table 3. Pin Function Descriptions

Pin No. Mnemonic Description

1 VOUT VGA Output.
2 VCOM

Common Ground When Using Plus and Minus Supply Voltages. For single-supply operation, provide half the

positive supply voltage at the VPOS pin to VCOM pin.
3 INPP Positive Input to Preamplifier.
4 INPN Negative Input to Preamplifier.
5 PRAO Preamplifier Output.
6 VNEG Negative Supply (−VPOS for Dual-Supply; GND for Single-Supply).
7 GAIN Gain Control Input Centered at VCOM.
8 VPOS Positive Supply.
EP Exposed Pad For best thermal performance, exposed pad must be soldered to PCB.

Rev. C | Page 6 of 32

AD8337

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TYPICAL PERFORMANCE CHARACTERISTICS

VS = ±2.5 V, TA = 25°C, RL = 500 Ω, including a 20 Ω snubbing resistor, f = 10 MHz, CL = 2 pF, VIN = 10 mV p-p, noninverting
configuration, unless otherwise noted.

% OF UNITS

60

50

40

30

20

10

500 UNITS

V

GAIN

V

GAIN

V

GAIN

= –0.4V

=0V

= +0.4V

30

+85°C
+25°C

25

–40°C

20

15

10

GAIN (dB)

5

0

–5

–600 –200–400 400 600200 800

–800

Figure 3. Gain vs. V

2.0

1.5

1.0

0.5

0

–0.5

GAIN ERROR (dB)

–1.0

–1.5

–2.0

–600 –200–400 400 600200 800

–800

Figure 4. Gain Error vs. V

2.0
RELATIVE TO BEST FIT
LINE FOR 10MHz

1.5

1.0

0

(mV)

V

GAIN

at Three Temperatures

GAIN

(See Figure 44)

0

(mV)

V

GAIN

at Three Temperatures

GAIN

(See Figure 44)

+85°C
+25°C
–40°C

f = 1MHz
f = 10MHz
f = 70MHz
f = 100MHz
f = 150MHz

05575-003

0

–0.2

–0.3

–0.4

–0.5

0

–0.1

GAIN ERROR (dB)

0.1

0.3

0.2

Figure 6. Gain Error Histogram for Three Values of V

50

500 UNITS
–0.4V ≤ V

40

30

20

% OF UNITS

10

05575-004

0

GAIN

≤ +0.4V

19.7 20.120.019.919.819.619.3 19.4 19.5

GAIN SCALING (dB/V)

0.4

GAIN

05575-006

0.5

05575-007

Figure 7. Gain Scaling Histogram

50

500 UNITS

40

0.5

0

–0.5

GAIN ERROR (dB)

–1.0

–1.5

–2.0

–600 –200–400 400 600200 800

Figure 5. Gain Error vs. V

0–800

V

(mV)

GAIN

at Five Frequencies

GAIN

05575-005

30

20

% OF UNITS

10

0

Figure 8. Intercept Histogram

(See Figure 44)

Rev. C | Page 7 of 32

12.6

INTERCEPT (d B)

05575-008

13.012.912.812.712.512.2 12.3 12.4

AD8337

www.BDTIC.com/ADI

30

eIN = 10mV p-p

25

20

15

10

GAIN (dB)

5

0

–5

100k 500M

= +0.7

V

GAIN

V

= +0.5

GAIN

= +0.2

V

GAIN

= 0

V

GAIN

= –0.2

V

GAIN

V

= –0.5

GAIN

V

= –0.7

GAIN

1M 10M 100M

FREQUENCY (Hz)

Figure 9. Frequency Response for Various Values of V

(See Figure 45)

GAIN

05575-009

30

V

= 0V

GAIN

25

20

15

10

GAIN (dB)

5

CL = 47pF

= 22pF

C

L

0

= 10pF

C

L

= 0pF

C

L

–5

100k 500M

1M 10M 100M

FREQUENCY (Hz)

Figure 12. Frequency Response for Three Values of CL

with a 20 Ω Snubbing Resistor (See Figure 45)

05575-012

20

15

10

5

0

GAIN (dB)

–5

–10

eIN = 10mV p-p

–15

100k 500M

V

= +0.7

GAIN

V

= +0.5

GAIN

= +0.2

V

GAIN

= 0

V

GAIN

= –0.2

V

GAIN

V

= –0.5

GAIN

V

= –0.7

GAIN

1M 10M 100M

FREQUENCY (Hz)

Figure 10. Frequency Response for Various Values of V

(See Figure 58)

30

V

= 0V

GAIN

= 10mV p-p

e

IN

25

20

15

10

GAIN (dB)

5

CL = 47pF

C

= 22pF

L

0

C

= 10pF

L

C

= 0pF

L

–5

100k 500M

1M 10M 100M

FREQUENCY (Hz)

Figure 11. Frequency Response for Three Values of CL

(See Figure 45)

—Inverting Input

GAIN

10

VS = ±2.5V

= ±5V

V

S

8

6

GAIN (dB)

4

2

05575-010

0

100k 500M

1M 10M 100M

FREQUENCY (Hz)

05575-013

Figure 13. Frequency Response—Preamp

(See Figure 46)

25

20

15

10

5

GROUP DELAY (ns)

0

–5

05575-011

–10

1M 100M

10M

FREQUENCY (Hz)

05575-014

Figure 14. Group Delay vs. Frequency

(See Figure 47)

Rev. C | Page 8 of 32

AD8337

www.BDTIC.com/ADI

10

8

6

4

2

0

–2

–4

OFFSET VOLTAGE (mV)

–6

+85°C

–8

+25°C
–40°C

–10

–800 800

–600 –400 –200 0 200 400 600

Figure 15. Offset Voltage vs. V

VS = ±2.5V

V

GAIN

GAIN

VS = ±5V

(mV)

at Three Temperatures

(See Figure 48)

05575-015

40

+85°C
+25°C
–40°C

35

30

25

NOISE (nV/√Hz)

20

15

–800 800

–600 –200–400 400 600200

Figure 18. Output-Referred Noise vs. V

V

GAIN

0

(mV)

at Three Temperatures

GAIN

(See Figure 50)

05575-018

80

500 UNITS

V

= –0.4V

GAIN

70

60

50

40

% OF UNITS

30

20

10

0

=0V

V

GAIN

= +0.4V

V

GAIN

–15 –10 –5 0 5 10 15 20 25

OUTPUT OFFSET VOLTAGE (mV)

Figure 16. Output Offset Voltage Histogram for Three Values of V

1k

VS = ±2.5V
V

= ±5V

S

100

10

IMPEDANCE (Ω)

1

GAIN

25

20

15

10

NOISE (nV/√Hz)

5

05575-016

0

–800 800

–600 –200–400 400 600200

V

GAIN

0

(mV)

Figure 19. Short-Circuit, Input-Referred Noise at Three Temperatures

+85°C
+25°C
–40°C

05575-019

(See Figure 50)

7

V

= 0.7V

GAIN

R

= R

FB2

= 100Ω

PREAMP GAIN = –1

PREAMP GAIN = +2

FB1

6

5

4

3

NOISE (nV /√Hz)

2

1

0.1

1M 500M

FREQUENCY (Hz)

100M10M

Figure 17. VGA Output Impedance vs. Frequency

(See Figure 49)

05575-017

0

100k 100M

Figure 20. Short-Circuit, Input-Referred Noise vs. Frequency at Maximum

Gain—Inverting and Noninverting Preamp Gain = −1 and +2

Rev. C | Page 9 of 32

1M 10M

FREQUENCY (Hz)

(See Figure 50)

05575-020

AD8337

www.BDTIC.com/ADI

10

f = 10MHz,
V

= 0.7V

GAIN

–40

HD3
HD2

INPUT-REFE RRED NOISE

1

RS THERMAL NOISE ALONE

INPUT-REFE RRED NOISE (n V/√Hz)

0.1
11

Figure 21. Input-Referred Noise vs. R

10 100 k

SOURCE RESISTANCE (Ω)

S

05575-021

–50

–60

–70

HARMONIC DIST ORTION (dBc)

–80

05 4010 3515 3020

Figure 24. Harmonic Distortion vs. Load Capacitance

(See Figure 61)

35

30

25

20

15

NOISE FI GURE (dB)

10

5
–800

50Ω SOURCE

WITH 50Ω SHUNT
TERMINATI ON AT INPUT

UNTERMI NATED

–600 –200–400 400 600200 800

Figure 22. Noise Figure vs. V

V

GAIN

0

(mV)

GAIN

05575-022

SECOND-ORDER HARMO NIC DISTORT ION (dBc)

–30

–40

–50

–60

–70

–80

–800

–600 800–400 600–200 4000

Figure 25. HD2 vs. V

1MHz
10MHz
35MHz
100MHz

(See Figure 51)

25

LOAD CAPACITANCE (pF)

(See Figure 52)

V

GAIN

200

(mV)

GAIN

at Four Frequencies

(See Figure 52)

45 50

05575-024

05575-025

THIRD-ORDER HARMO NICDISTO RTION (dBc)

–30

–40

–50

–60

–70

–80

–800

–600 800–400 600–200 4000

Figure 26. HD3 vs. V

(See Figure 52)

–40

V

OUT

V

GAIN

–50

dBc)

–60

–70

HARMONIC DISTORTION (

–80

200 400 600 800

0

= 1V p-p

= 0V

LOAD RESIST ANCE (

HD3 VS = ±2.5V
HD3 V
HD2 V
HD2 V

Ω

)

Figure 23. Harmonic Distortion vs. RL and Supply Voltage

(See Figure 52)

= ±5V

S

= ±2.5V

S

= ±5V

S

05575-023

2.0k1.0k 1.2k 1.4k 1.6k 1.8k

Rev. C | Page 10 of 32

V

200

(mV)

GAIN

at Four Frequencies

GAIN

1MHz
10MHz
35MHz
100MHz

05575-026