ANALOG DEVICES ADA4937-1, ADA4937-2 Service Manual

Ultralow Distortion

–

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FEATURES

Extremely low harmonic distortion

−112 dBc HD2 @ 10 MHz

−84 dBc HD2 @ 70 MHz

−77 dBc HD2 @ 100 MHz

−102 dBc HD3 @ 10 MHz

−91 dBc HD3 @ 70 MHz

−84 dBc HD3 @ 100 MHz Low input voltage noise: 2.2 nV/√Hz High speed

−3 dB bandwidth of 1.9 GHz, G = 1

Slew rate: 6000 V/μs, 25% to 75% Fast overdrive recovery of 1 ns

0.5 mV typical offset voltage Externally adjustable gain Differential-to-differential or single-ended-to-differential

oper

ation Adjustable output common-mode voltage Single-supply operation: 3.3 V to 5 V

APPLICATIONS

ADC drivers Single-ended-to-differential converters IF and baseband gain blocks Differential buffers Line drivers

GENERAL DESCRIPTION

The ADA4937 is a low noise, ultralow distortion, high speed differential amplifier. It is an ideal choice for driving high performance ADCs with resolutions up to 16 bits from dc to 100 MHz. The adjustable level of the output common mode allows the ADA4937 to match the input of the ADC. The internal common-mode feedback loop also provides exceptional output balance as well as suppression of even-order harmonic distortion products.

With the ADA4937, differential gain configurations are easily

ealized with a simple external feedback network of four

r resistors that determine the closed-loop gain of the amplifier.

The ADA4937 is fabricated using Analog Devices, Inc. proprietary silico

n-germanium (SiGe), complementary bipolar process, enabling it to achieve very low levels of distortion with an input voltage noise of only 2.2 nV/√Hz. The low dc offset and excellent dynamic performance of the ADA4937 make it well suited for a wide variety of data acquisition and signal processing applications.

Differential ADC Driver

ADA4937-1/ADA4937-2

FUNCTIONAL BLOCK DIAGRAMS

1–FB

2+IN

3–IN

4+FB

1–IN1 2+FB1 3+V

S1

4+V

S1

5–FB2 6+IN2

55

–60

–65

–70

–75

–80

–85

–90

–95

DISTORTION (dBc)

–100

–105

–110

–115

The ADA4937 is available in a Pb-free, 3 mm × 3 mm 16-lead LFCSP (ADA4937-1, single) or a Pb-free, 4 mm × 4 mm 24-lead LFCSP (ADA4937-2, dual). The pinout has been optimized to facilitate PCB layout and minimize distortion. The ADA4937-1 is specified to operate over the −40°C to +105°C temperature range, and the ADA4937-2 operates over −40°C to +85°C; both operate at 3.3 V and 5 V supplies.

HD2, VS=5.0V HD3, VS=5.0V HD2, VS=3.3V HD3, VS=3.3V

1 10 100

Figure 3. Harmonic Distortion vs. Frequency

S

–V

14

13

15

16

ADA4937-1

5

6

S

+V

12 PD

11 –OUT

10 +OUT

9V

8

7

S

+V

Figure 1. ADA4937-1

S1

–V

–FB1

+IN1

24

ADA4937-2

7

–IN2

–OUT1

PD1

20

19

21

22

23

18 +OUT1 17 V 16 –V 15

14 13 –OUT2

9

8

11

12

10

S2

UT2

+V

OCM2

+FB2

V

+O

Figure 2. ADA4937-2

FREQUENCY (MHz)

–V PD2

OCM

OCM1

S2 S2

06591-001

06591-002

06591-003

Rev. A

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.

ADA4937-1/ADA4937-2

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REVISION HISTORY

11/07—Rev. 0 to Rev. A

Added the ADA4937-2......................................................Universal

Changes to Features.......................................................................... 1

Changes to Specifications................................................................ 3

Changes to Figure 4.......................................................................... 7

Changes to Typical Performance Characteristics......................... 9

Inserted Figure 44........................................................................... 15

Added the Terminating a Single-Ended Input Section .............19

Changes to Table 10 and Table 11 ................................................ 21

Changes to Layout, Grounding, and Bypassing Section ........... 22

Inserted Figure 59, Figure 60, and Figure 61 ..............................22

Updated Outline Dimensions....................................................... 26

Changes to Ordering Guide.......................................................... 26

5/07—Revision 0: Initial Version

Rev. A | Page 2 of 28

ADA4937-1/ADA4937-2

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SPECIFICATIONS

5 V OPERATION

TA = 25°C, +VS = 5 V, −VS = 0 V, V All specifications refer to single-ended input and differential outputs, unless otherwise noted.

±DIN to ±OUT Performance

Table 1.

Parameter Conditions Min Typ Max Unit

DYNAMIC PERFORMANCE

−3 dB Small Signal Bandwidth V Bandwidth for 0.1 dB Flatness V Large Signal Bandwidth V Slew Rate V Overdrive Recovery Time VIN = 0 V to 1.5 V step; G = 3.16 <1 ns

NOISE/HARMONIC PERFORMANCE See Figure 48 for distortion test circuit

Second Harmonic V V V Third Harmonic V V V IMD f1 = 70 MHz; f2 = 70.1 MHz; V Voltage Noise (RTI) f = 100 kHz 2.2 nV/√Hz Input Current Noise f = 100 kHz 4 pA/√Hz Noise Figure G = 4; RT = 136 Ω; RF = 200 Ω; RG = 37 Ω; f = 100 MHz 15 dB Crosstalk (ADA4937-2) f = 100 MHz −72 dB

INPUT CHARACTERISTICS

Offset Voltage V T Input Bias Current −30 −21 −10 μA T Input Offset Current −2 +0.5 +2 μA Input Resistance Differential 6 MΩ Common mode 3 MΩ Input Capacitance 1 pF Input Common-Mode Voltage 0.3 to 3.0 V CMRR ∆V

OUTPUT CHARACTERISTICS

Output Voltage Swing Maximum ∆V Linear Output Current >100 mA Output Balance Error

= +VS/2, RT = 61.9 , RG = RF = 200 , G = 1, R

OCM

= 0.1 V p-p 1900 MHz

OUT, dm

= 0.1 V p-p 200 MHz

OUT, dm

= 2 V p-p 1700 MHz

OUT, dm

= 2 V p-p; 25% to 75% 6000 V/μs

OUT, dm

= 2 V p-p; 10 MHz −112 dBc

OUT, dm

= 2 V p-p; 70 MHz −84 dBc

OUT, dm

= 2 V p-p; 100 MHz −77 dBc

OUT, dm

= 2 V p-p; 10 MHz −102 dBc

OUT, dm

= 2 V p-p; 70 MHz −91 dBc

OUT, dm

= 2 V p-p; 100 MHz −84 dBc

OUT, dm

= 2 V p-p −91 dBc

OUT, dm

∆V

OS, dm

MIN

OUT, dm

OUT, cm

= V

to T

/2; V

= V

OUT, dm

variation ±1 μV/°C

MAX

variation 0.01 μA/°C

MAX

/∆V

DIN+

; ∆V

IN, cm

; single-ended output; RF = RG = 10 kΩ 0.9 4.1 V

OUT

; ∆V

OUT, dm

= 2.5 V −2.5 ±0.5 +2.5 mV

DIN−

= ±1 V −69 −80 dB

= 1 V; 10 MHz;

see Figure 47 for test circuit

= 1 kΩ, unless otherwise noted.

L, dm

−61 dB

Rev. A | Page 3 of 28

ADA4937-1/ADA4937-2

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V

to ±OUT Performance

OCM

Table 2.

Parameter Conditions Min Typ Max Unit

V

DYNAMIC PERFORMANCE

OCM

−3 dB Bandwidth 440 MHz Slew Rate VIN = 1.5 V to 3.5 V; 25% to 75% 1150 V/μs Input Voltage Noise (RTI) f = 100 kHz 7.5 nV/√Hz

V

INPUT CHARACTERISTICS

OCM

Input Voltage Range 1.2 3.8 V Input Resistance 8 10 12 kΩ Input Offset Voltage V Input Bias Current 0.5 μA V

CMRR ΔV

OCM

Gain ΔV

POWER SUPPLY

Operating Range 3.0 5.25 V Quiescent Current per Amplifier 38.0 39.5 42.0 mA T Powered down 0.02 0.3 0.5 mA Power Supply Rejection Ratio ΔV

POWER-DOWN (PD)

PD Input Voltage Enabled ≥2 V Turn-Off Time 1 μs Turn-On Time 200 ns PD Bias Current per Amplifier

Enabled Disabled

OPERATING TEMPERATURE RANGE −40 +85 °C

OS, cm

OUT, dm

OUT, cm

MIN

OUT, dm

= V

to T

; V

= V

OUT, cm

DIN+

/ΔV

; ΔV

OCM

/ΔV

; ΔV

OCM

variation 17 μA/°C

MAX

= +VS/2 2 7.1 mV

DIN−

= ±1 V −70 −75 dB

= ±1 V 0.97 0.98 1.00 V/V

/ΔVS; ΔVS = 1 V −70 −90 dB

Powered down ≤1 V

PD PD

= 5 V = 0 V

10 30 50 μA

−300 −200 −150 μA

Rev. A | Page 4 of 28

ADA4937-1/ADA4937-2

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3.3 V OPERATION

TA = 25°C, +VS = 3.3 V, −VS = 0 V, V specifications refer to single-ended input and differential outputs, unless otherwise noted.

±DIN to ±OUT Performance

Table 3.

Parameter Conditions Min Typ Max Unit

DYNAMIC PERFORMANCE

−3 dB Small Signal Bandwidth V Bandwidth for 0.1 dB Flatness V Large Signal Bandwidth V Slew Rate V Overdrive Recovery Time VIN = 0 V to 1.0 V step; G = 3.16 <1 ns

NOISE/HARMONIC PERFORMANCE See Figure 48 for distortion test circuit

Second Harmonic V V V Third Harmonic V V V IMD f1 = 70 MHz; f2 = 70.1 MHz; V Voltage Noise (RTI) f = 100 kHz 2.2 nV/√Hz Input Current Noise f = 100 kHz 4 pA/√Hz Noise Figure G = 4; RT = 136 Ω; RF = 200 Ω; RG = 37 Ω; f = 100 MHz 15 dB Crosstalk (ADA4937-2) f = 100 MHz −72 dB

INPUT CHARACTERISTICS

Offset Voltage V T Input Bias Current −50 −20 −10 μA T Input Resistance Differential 6 MΩ Common mode 3 MΩ Input Capacitance 1 pF Input Common-Mode Voltage 0.3 to 1.2 V CMRR ∆V

OUTPUT CHARACTERISTICS

Output Voltage Swing Maximum ∆V Linear Output Current 95 mA Output Balance Error

= +VS/2, RT = 61.9 , RG = RF = 200 , G = 1, R

OCM

= 0.1 V p-p 1800 MHz

OUT, dm

= 0.1 V p-p 200 MHz

OUT, dm

= 2 V p-p 1300 MHz

OUT, dm

= 2 V p-p; 25% to 75% 4000 V/μs

OUT, dm

= 2 V p-p; 10 MHz −113 dBc

OUT, dm

= 2 V p-p; 70 MHz −85 dBc

OUT, dm

= 2 V p-p; 100 MHz −77 dBc

OUT, dm

= 2 V p-p; 10 MHz −95 dBc

OUT, dm

= 2 V p-p; 70 MHz −77 dBc

OUT, dm

= 2 V p-p; 100 MHz −71 dBc

OUT, dm

= 2 V p-p −87 dBc

OUT, dm

∆V

OS, dm

MIN

OUT, dm

OUT, cm

= V

to T

/2; V

= V

OUT, dm

variation ±1 μV/°C

MAX

variation 0.01 μA/°C

MAX

/∆V

DIN+

; ∆V

IN, cm

; single-ended output; RF = RG = 10 kΩ 0.8 2.5 V

OUT

; ∆V

OUT, dm

= +VS/2 −2.5 ±0.5 +2.5 mV

DIN−

= ±1 V −67 −80 dB

= 1 V; f = 10 MHz;

see Figure 47 for test circuit

= 1 kΩ, unless otherwise noted. All

L, dm

−61 dB

Rev. A | Page 5 of 28

ADA4937-1/ADA4937-2

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V

to ±OUT Performance

OCM

Table 4.

Parameter Conditions Min Typ Max Unit

V

DYNAMIC PERFORMANCE

OCM

−3 dB Bandwidth 440 MHz Slew Rate VIN = 0.9 V to 2.4 V; 25% to 75% 900 V/μs Input Voltage Noise (RTI) f = 100 kHz 7.5 nV/√Hz

V

INPUT CHARACTERISTICS

OCM

Input Voltage Range 1.2 2.1 V Input Resistance 10 kΩ Input Offset Voltage V Input Bias Current 0.5 μA V

CMRR ∆V

OCM

Gain ∆V

POWER SUPPLY

Operating Range 3.0 5.25 V Quiescent Current per Amplifier 36 38 40 mA T Powered down 0.02 0.2 0.5 mA Power Supply Rejection Ratio ∆V

POWER-DOWN (PD)

PD Input Voltage Enabled ≥2 V Turn-Off Time 1 μs Turn-On Time 200 ns PD Bias Current per Amplifier

Enabled Disabled

OPERATING TEMPERATURE RANGE −40 +105 °C

OS, cm

OUT, dm

OUT, cm

MIN

OUT, dm

= V

to T

; V

= V

OUT, cm

DIN+

/∆V

; ∆V

OCM

/∆V

; ∆V

OCM

variation 17 μA/°C

MAX

= 1.67 V 2 7.1 mV

DIN−

= ±1 V −70 −75 dB

= ±1 V 0.97 0.98 1.00 V/V

/∆VS; ∆VS = 1 V −70 −90 dB

Powered down ≤1 V

PD PD

= 3.3 V = 0 V

10 20 30 μA

−200 −120 −100 μA

Rev. A | Page 6 of 28

ADA4937-1/ADA4937-2

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ABSOLUTE MAXIMUM RATINGS

Table 5.

Parameter Rating

Supply Voltage 5.5 V Power Dissipation See Figure 4 Storage Temperature Range −65°C to +125°C Operating Temperature Range

ADA4937-1 −40°C to +105°C

ADA4937-2 −40°C to +85°C Lead Temperature (Soldering, 10 sec) 300°C Junction Temperature 150°C

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 device (including exposed pad) soldered to a high thermal conductivity 2s2p circuit board, as described in EIA/JESD 51-7.

Table 6. Thermal Resistance

Package Type θJA Unit

16-Lead LFCSP (Exposed Pad) 95 °C/W 24-Lead LFCSP (Exposed Pad) 67 °C/W

Maximum Power Dissipation

The maximum safe power dissipation in the ADA4937 package is limited by the associated rise in junction temperature (T the die. At approximately 150°C, which is the glass transition temperature, the plastic changes its properties. Even temporarily exceeding this temperature limit can change the stresses that the package exerts on the die, permanently shifting the parametric performance of the ADA4937. Exceeding a junction temperature of 150°C for an extended period can result in changes in the silicon devices, potentially causing failure.

) on

J

The power dissipated in the package (P quiescent power dissipation and the power dissipated in the package due to the load drive. The quiescent power is the voltage between the supply pins (V

) times the quiescent current (IS).

S

The power dissipated due to the load drive depends upon the particular application. The power due to load drive is calculated by multiplying the load current by the associated voltage drop across the device. RMS voltages and currents must be used in these calculations.

Airflow increases heat dissipation, effectively reducing θ addition, more metal directly in contact with the package leads/exposed pad from metal traces, through holes, ground, and power planes reduces θ

.

JA

Figure 4 shows the maximum safe power dissipation in the

ackage vs. the ambient temperature for the single 16-lead

p LFCSP (95°C/W) and the dual 24-lead LFCSP (67°C/W) on a JEDEC standard 4-layer board.

3.5

3.0

2.5

2.0

1.5

1.0

MAXIMUM POWER DISSIPATION (W)

0.5

0

–40 90

Figure 4. Maximum Power Dissipation vs. Temperature for a 4-Layer Board

ADA4937-1

–30–20–100 1020304050607080

ADA4937-2

AMBIENT TEMPERATURE (°C)

ESD CAUTION

) is the sum of the

D

JA

. In

06591-004

Rev. A | Page 7 of 28

ADA4937-1/ADA4937-2

+

–

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PIN CONFIGURATION AND FUNCTION DESCRIPTIONS

S

1–FB

2+IN

ADA4937-1

3–IN

(Not to Scale)

4+FB

–V

15

16

PIN 1 INDICATO R

TOP VIEW

5

6

S

+V

S

–V

14

13

–IN1

12 PD

11 –OUT

10 +OUT

9V

OCM

8

7

S

+V

06591-005

FB1 +V +V

FB2

+IN2

S1 S1

1 2 3

ADA4937-2

4 5 6

+IN1

24

PIN 1 INDICATOR

TOP VIEW

(Not to Scale)

7

–IN2

–OUT1

–VS1–VS1–FB1

PD1

20

19

21

22

23

18

+OUT1

17

V

OCM1

–V

16

S2

–V

15

S2

14

PD2

13

–OUT2

9

8

11

12

10

S2

CM2

+V

O

+FB2

V

+OUT2

06591-006

Figure 5. ADA4937-1 Pin Configuration

Figure 6. ADA4937-2 Pin Configuration

Table 7. ADA4937-1 Pin Function Descriptions

Pin No. Mnemonic Description

1 −FB Negative Output for Feedback Component Connection. 2 +IN Positive Input Summing Node. 3 −IN Negative Input Summing Node. 4 +FB Positive Output for Feedback Component Connection. 5 to 8 +VS Positive Supply Voltage. 9 V

Output Common-Mode Voltage.

OCM

10 +OUT Positive Output for Load Connection. 11 −OUT Negative Output for Load Connection. 12

PD

Power-Down Pin.

13 to 16 −VS Negative Supply Voltage.

Table 8. ADA4937-2 Pin Function Descriptions

Pin No. Mnemonic Description

1 −IN1 Negative Input Summing Node 1. 2 +FB1 Positive Output Feedback Pin 1. 3, 4 +VS1 Positive Supply Voltage 1. 5 −FB2 Negative Output Feedback Pin 2. 6 +IN2 Positive Input Summing Node 2. 7 −IN2 Negative Input Summing Node 2. 8 +FB2 Positive Output Feedback Pin 2. 9, 10 +VS2 Positive Supply Voltage 2. 11 V

Output Common-Mode Voltage 2.

OCM2

12 +OUT2 Positive Output 2. 13 −OUT2 Negative Output 2. 14

PD2

Power-Down Pin 2.

15, 16 −VS2 Negative Supply Voltage 2. 17 V

Output Common-Mode Voltage 1.

OCM1

18 +OUT1 Positive Output 1. 19 −OUT1 Negative Output 1. 20

PD1

Power-Down Pin 1.

21, 22 −VS1 Negative Supply Voltage 1. 23 −FB1 Negative Output Feedback Pin 1. 24 +IN1 Positive Input Summing Node 1.

Rev. A | Page 8 of 28

ADA4937-1/ADA4937-2

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TYPICAL PERFORMANCE CHARACTERISTICS

TA = 25°C, +VS = 5 V, −VS = 0 V, V noted. Refer to Figure 46 for test setup.

6

OUT, dm

= 2 V p-p, V

= +VS /2, RT = 61.9 , RG = RF = 200 , G = 1, R

OCM

6

= 1 kΩ, unless otherwise

L, dm

3

0

–3

–6

–9

–12

NORMALIZ ED CLOSED-L OOP GAI N (dB)

G = +1, RF = 200Ω G = +2, R

= 402Ω

F

G = +5, R

= 402Ω

–15

1 10 100 1000

F

FREQUENCY (MHz )

Figure 7. Small Signal Frequency Response for Various Gains,

V

= 100 mV p-p

OUT, dm

6

VS = 3.3V

VS = 5.0V

3

0

–3

–6

–9

CLOSED-LOOP GAIN (dB)

–12

3

0

–3

–6

–9

–12

NORMALIZ ED CLOSED- LOOP G AIN (dB)

6591-075

G = +1, RF = 200Ω G = +2, R

= 402Ω

F

G = +5, R

= 402Ω

–15

1 10 100 1000

F

FREQUENCY (MHz)

06591-076

Figure 10. Large Signal Frequency Response for Various Gains

6

VS = 3.3V

VS = 5.0V

3

0

–3

–6

–9

CLOSED-LOOP GAIN (dB)

–12

–15

1 10 100 1000

FREQUENCY (MHz)

Figure 8. Small Signal Frequency Response for Various Supplies,

= 100 mV p-p

V

OUT, dm

6

+105°C +25°C –40°C

3

0

–3

–6

CLOSED-LOOP GAIN (dB)

–9

–12

1 10 100 1000

FREQUENCY (MHz)

Figure 9. Small Signal Frequency Response for Various Temperatures,

= 100 mV p-p

V

OUT, dm

06591-008

06591-009

Rev. A | Page 9 of 28

–15

1 10 100 1000

FREQUENCY (MHz)

Figure 11. Large Signal Frequency Response for Various Supplies

6

+105°C +25°C –40°C

3

0

–3

–6

CLOSED-LOOP GAIN (dB)

–9

–12

1 10 100 1000

FREQUENCY (MHz)

Figure 12. Large Signal Frequency Response for Various Temperatures

06591-011

06591-012

ANALOG DEVICES ADA4937-1, ADA4937-2 Service Manual

Specifications and Main Features

Frequently Asked Questions

User Manual

FEATURES

APPLICATIONS

GENERAL DESCRIPTION

FUNCTIONAL BLOCK DIAGRAMS

TABLE OF CONTENTS

REVISION HISTORY

SPECIFICATIONS

5 V OPERATION

±DIN to ±OUT Performance

3.3 V OPERATION

±DIN to ±OUT Performance

ABSOLUTE MAXIMUM RATINGS

THERMAL RESISTANCE

Maximum Power Dissipation

ESD CAUTION

PIN CONFIGURATION AND FUNCTION DESCRIPTIONS

TYPICAL PERFORMANCE CHARACTERISTICS