ANALOG DEVICES ADA4939-1, ADA4939-2 Service Manual

Ultralow Distortion

–

FEATURES

Extremely low harmonic distortion

−102 dBc HD2 @ 10 MHz

−83 dBc HD2 @ 70 MHz

−77 dBc HD2 @ 100 MHz

−101 dBc HD3 @ 10 MHz

−97 dBc HD3 @ 70 MHz

−91 dBc HD3 @ 100 MHz Low input voltage noise: 2.3 nV/√Hz High speed

−3 dB bandwidth of 1.4 GHz, G = 2

Slew rate: 6800 V/μs, 25% to 75%

Fast overdrive recovery of <1 ns ±0.5 mV typical offset voltage Externally adjustable gain Stable for differential gains ≥2 Differential-to-differential or single-ended-to-differential

operation 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 ADA4939 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 output common-mode voltage is user adjustable by means of an internal common-mode feedback loop, allowing the ADA4939 output to match the input of the ADC. The internal feedback loop also provides exceptional output balance as well as suppression of even-order harmonic distortion products.

With the ADA4939, differential gain configurations are easily realized with a simple external feedback network of four resistors that determine the closed-loop gain of the amplifier.

The ADA4939 is fabricated using Analog Devices, Inc., proprietary silicon-germanium (SiGe), complementary bipolar process, enabling it to achieve very low levels of distortion with an input voltage noise of only 2.3 nV/√Hz. The low dc offset and excellent dynamic performance of the ADA4939 make it well suited for a wide variety of data acquisition and signal processing applications.

Differential ADC Driver

ADA4939-1/ADA4939-2

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

60

–65

–70

–75

–80

–85

–90

–95

HARMONIC DIST ORTIO N (dBc)

–100

–105

–110

1 10 100

The ADA4939 is available in a Pb-free, 3 mm × 3 mm 16-lead LFCSP (ADA4939-1, single) or a Pb-free, 4 mm × 4 mm 24-lead LFCSP (ADA4939-2, dual). The pinout has been optimized to facilitate PCB layout and minimize distortion. The ADA4939-1 and the ADA4939-2 are specified to operate over the −40°C to +105°C temperature range; both operate on supplies between

3.3 V and 5 V.

= 2V p-p

V

OUT, dm

HD2 HD3

Figure 3. Harmonic Distortion vs. Frequency

S

–V

14

13

15

16

ADA4939-1

5

6

S

+V

12 PD

11 –OUT

10 +OUT

9V

8

7

S

+V

Figure 1. ADA4939-1

S1

–V

–FB1

+IN1

24

ADA4939-2

7

–IN2

PD1

–OUT1

20

19

21

22

23

18 + OUT1 17 V 16 – V 15

14 13 –O UT2

9

8

11

12

10

S2

+V

OCM2

+FB2

V

+OUT2

Figure 2. ADA4939-2

FREQUENCY (MHz)

–V PD2

OCM

OCM1

S2 S2

07429-001

07429-002

07429-021

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.

ADA4939-1/ADA4939-2

REVISION HISTORY

5/08—Revision 0: Initial Version

Rev. 0 | Page 2 of 24

ADA4939-1/ADA4939-2

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. Refer to

±DIN to V

Performance

OUT, dm

Table 1.

Parameter Conditions Min Typ Max Unit

DYNAMIC PERFORMANCE

−3 dB Small Signal Bandwidth V Bandwidth for 0.1 dB Flatness V 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 41 for distortion test circuit

Second Harmonic V V V Third Harmonic V V V IMD f1 = 70 MHz, f2 = 70.1 MHz, V f Voltage Noise (RTI) f = 100 kHz 2.3 nV/√Hz Input Current Noise f = 100 kHz 6 pA/√Hz Crosstalk f = 100 MHz, ADA4939-2 −80 dB

INPUT CHARACTERISTICS

Offset Voltage V T Input Bias Current −26 −10 +2.2 μA T Input Offset Current −11.2 +0.5 +11.2 μA Input Resistance Differential 180 kΩ Common mode 450 kΩ Input Capacitance 1 pF Input Common-Mode Voltage 1.1 3.9 V CMRR ∆V

OUTPUT CHARACTERISTICS

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

= +VS/2, RF = 402 , RG = 200 , RT = 60.4  (when used), R

OCM

= 0.1 V p-p 1400 MHz

OUT, dm

= 0.1 V p-p, ADA4939-1 300 MHz

OUT, dm

= 0.1 V p-p, ADA4939-2 90 MHz

OUT, dm

= 2 V p-p 1400 MHz

OUT, dm

= 2 V p-p, 25% to 75% 6800 V/μs

OUT, dm

= 2 V p-p, 10 MHz −102 dBc

OUT, dm

= 2 V p-p, 70 MHz −83 dBc

OUT, dm

= 2 V p-p, 100 MHz −77 dBc

OUT, dm

= 2 V p-p, 10 MHz −101 dBc

OUT, dm

= 2 V p-p, 70 MHz −97 dBc

OUT, dm

= 2 V p-p, 100 MHz −91 dBc

OUT, dm

= 2 V p-p −95 dBc

OUT, dm

= 140 MHz, f2 = 140.1 MHz, V

1

= V

OS, dm

to T

MIN

to T

MIN

OUT, dm

∆V

OUT, cm

Figure 40 for test circuit

see

/2, V

OUT, dm

variation ±2.0 μV/°C

MAX

variation ±0.5 μA/°C

MAX

/∆V

IN, cm

OUT

/∆V

OUT, dm

= V

DIN+

, ∆V

= ±1 V −83 −77 dB

IN, cm

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

, ∆V

OUT, dm

DIN−

= 1 V, 10 MHz,

= 2 V p-p −89 dBc

OUT, dm

= 2.5 V −3.4 ±0.5 +2.8 mV

= 1 kΩ, unless otherwise noted.

L, dm

Figure 42 for signal definitions.

−64 dB

Rev. 0 | Page 3 of 24

ADA4939-1/ADA4939-2

V

to V

OCM

Table 2.

Parameter Conditions Min Typ Max Unit

V

DYNAMIC PERFORMANCE

OCM

−3 dB Bandwidth 670 MHz Slew Rate VIN = 1.5 V to 3.5 V, 25% to 75% 2500 V/μs Input Voltage Noise (RTI) f = 100 kHz 7.5 nV/√Hz

V

INPUT CHARACTERISTICS

OCM

Input Voltage Range 1.3 3.5 V Input Resistance 8.3 9.7 11.5 kΩ Input Offset Voltage V V

CMRR ΔV

OCM

Gain ΔV

General Performance

Table 3.

Parameter Conditions Min Typ Max Unit

POWER SUPPLY

Operating Range 3.0 5.25 V Quiescent Current per Amplifier 35.1 36.5 37.7 mA T Powered down 0.26 0.32 0.38 mA Power Supply Rejection Ratio ΔV

POWER-DOWN (PD)

PD Input Voltage Enabled ≥2 V Turn-Off Time 500 ns Turn-On Time 100 ns PD Pin Bias Current per Amplifier

Enabled Disabled

OPERATING TEMPERATURE RANGE −40 +105 °C

Performance

OUT, cm

OS, cm

OUT, dm

OUT, cm

= V

OUT, cm

/ΔV

OCM

, V

= V

= +VS/2 −3.7 ±0.5 +3.7 mV

DIN−

= ±1 V −90 −73 dB = ±1 V 0.97 0.98 0.99 V/V

variation 16 μA/°C

MAX

/ΔVS, ΔVS = 1 V −90 −80 dB

MIN

DIN+

, ΔV , ΔV

to T

OUT, dm

OCM

Powered down ≤1 V

PD = 5 V PD = 0 V

30 μA

−200 μA

Rev. 0 | Page 4 of 24

ADA4939-1/ADA4939-2

3.3 V OPERATION

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

±DIN to V

Performance

OUT, dm

Table 4.

Parameter Conditions Min Typ Max Unit

DYNAMIC PERFORMANCE

−3 dB Small Signal Bandwidth V Bandwidth for 0.1 dB Flatness V 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 41 for distortion test circuit

Second Harmonic V V V Third Harmonic V V V IMD f1 = 70 MHz, f2 = 70.1 MHz, V f Voltage Noise (RTI) f = 100 kHz 2.3 nV/√Hz Input Current Noise f = 100 kHz 6 pA/√Hz Crosstalk f = 100 MHz, ADA4939-2 −80 dB

INPUT CHARACTERISTICS

Offset Voltage V T Input Bias Current −26 −10 +2.2 μA T Input Offset Current −11.2 ±0.4 +11.2 Input Resistance Differential 180 kΩ Common mode 450 kΩ Input Capacitance 1 pF Input Common-Mode Voltage 0.9 2.4 V CMRR ∆V

OUTPUT CHARACTERISTICS

Output Voltage Swing Maximum ∆V Linear Output Current 75 mA Output Balance Error

= +VS/2, RF = 402 , RG = 200 , RT = 60.4  (when used), R

OCM

= 0.1 V p-p 1400 MHz

OUT, dm

= 0.1 V p-p, ADA4939-1 300 MHz

OUT, dm

= 0.1 V p-p, ADA4939-2 90 MHz

OUT, dm

= 2 V p-p 1400 MHz

OUT, dm

= 2 V p-p, 25% to 75% 5000 V/μs

OUT, dm

= 2 V p-p, 10 MHz −100 dBc

OUT, dm

= 2 V p-p, 70 MHz −90 dBc

OUT, dm

= 2 V p-p, 100 MHz −83 dBc

OUT, dm

= 2 V p-p, 10 MHz −94 dBc

OUT, dm

= 2 V p-p, 70 MHz −82 dBc

OUT, dm

= 2 V p-p, 100 MHz −75 dBc

OUT, dm

= 2 V p-p −87 dBc

OUT, dm

= 140 MHz, f2 = 140.1 MHz, V

1

= V

OS, dm

to T

MIN

to T

MIN

OUT, dm

∆V

OUT, cm

Figure 40 for test circuit

see

/2, V

OUT, dm

variation ±2.0 μV/°C

MAX

variation ±0.5 μA/°C

MAX

/∆V

IN, cm

OUT

/∆V

OUT, dm

= V

DIN+

, ∆V

= ±1 V −85 −75 dB

IN, cm

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

, ∆V

OUT, dm

DIN−

= 1 V, f = 10 MHz,

= 2 V p-p −70 dBc

OUT, dm

= +VS/2 −3.5 ±0.5 +3.5 mV

= 1 kΩ, unless otherwise noted.

L, dm

Figure 42 for signal definitions.

−61 dB

Rev. 0 | Page 5 of 24

ADA4939-1/ADA4939-2

V

to V

OCM

Table 5.

Parameter Conditions Min Typ Max Unit

V

DYNAMIC PERFORMANCE

OCM

−3 dB Bandwidth 560 MHz Slew Rate VIN = 0.9 V to 2.4 V, 25% to 75% 1250 V/μs Input Voltage Noise (RTI) f = 100 kHz 7.5 nV/√Hz

V

INPUT CHARACTERISTICS

OCM

Input Voltage Range 1.3 1.9 V Input Resistance 8.3 9.7 11.2 kΩ Input Offset Voltage V V

CMRR ∆V

OCM

Gain ∆V

General Performance

Table 6.

Parameter Conditions Min Typ Max Unit

POWER SUPPLY

Operating Range 3.0 5.25 V Quiescent Current per Amplifier 32.8 34.5 36.0 mA T Powered down 0.16 0.20 0.26 mA Power Supply Rejection Ratio ∆V

POWER-DOWN (PD)

PD Input Voltage Enabled ≥2 V Turn-Off Time 500 ns Turn-On Time 100 ns PD Pin Bias Current per Amplifier

Enabled Disabled

OPERATING TEMPERATURE RANGE −40 +105 °C

Performance

OUT, cm

= V

OS, cm

OUT, dm

OUT, cm

to T

MIN

OUT, dm

variation 16 μA/°C

MAX

/∆VS, ∆VS = 1 V −84 −72 dB

OUT, cm

/∆V

OCM

, V

= V

= 1.67 V −3.7 ±0.5 +3.7 mV

DIN−

= ±1 V −75 −73 dB = ±1 V 0.97 0.98 0.99 V/V

, ∆V , ∆V

DIN+

OCM

Powered down ≤1 V

PD = 3.3 V PD = 0 V

26 μA

−137 μA

Rev. 0 | Page 6 of 24

ADA4939-1/ADA4939-2

ABSOLUTE MAXIMUM RATINGS

Table 7.

Parameter Rating

Supply Voltage 5.5 V Power Dissipation See Figure 4

Input Current, +IN, −IN,

PD

±5 mA

Storage Temperature Range −65°C to +125°C Operating Temperature Range

ADA4939-1 −40°C to +105°C

ADA4939-2 −40°C to +105°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.

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 package vs. the ambient temperature for the single 16-lead LFCSP (98°C/W) and the dual 24-lead LFCSP (67°C/W) on a JEDEC standard four-layer board with the exposed pad soldered to a PCB pad that is connected to a solid plane.

3.0

2.5

ADA4939-2

2.0

) is the sum of the

D

JA

. In

Table 8. Thermal Resistance

Package Type θ

Unit

JA

ADA4939-1, 16-Lead LFCSP (Exposed Pad) 98 °C/W ADA4939-2, 24-Lead LFCSP (Exposed Pad) 67 °C/W

MAXIMUM POWER DISSIPATION

The maximum safe power dissipation in the ADA4939 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 ADA4939. Exceeding a junction temperature of 150°C for an extended period can result in changes in the silicon devices, potentially causing failure.

) on

J

1.5

ADA4939-1

1.0

0.5

MAXIMUM POWER DISSIPATION (W)

0

–40 100806040200–20

Figure 4. Maximum Power Dissipation vs. Ambient Temperature for

AMBIENT TEM PERATURE (°C)

a Four-Layer Board

ESD CAUTION

07429-004

Rev. 0 | Page 7 of 24

ADA4939-1/ADA4939-2

+

–

PIN CONFIGURATIONS AND FUNCTION DESCRIPTIONS

S

1–FB

2+IN

ADA4939-1

3–IN

(Not to Scale)

4+FB

–V

15

16

PIN 1 INDICATO R

TOP VIEW

5

6

S

+V

S

–V

14

13

12 PD

11 –OUT

10 +OUT

9V

OCM

8

7

S

+V

07429-005

–IN1

FB1 +V +V

FB2

+IN2

S1 S1

1 2 3

ADA4939-2

4 5

(Not to Scale)

6

FB1

+IN1

22

23

24

PIN 1 INDICATOR

TOP VIEW

9

7

8

S2

N2 –I

+V

+FB2

–OUT1

–VS1–VS1–

PD1

20

19

21

+OUT1

18 17

V

OCM1

16

–V

S2

–V

15

S2

14

PD2 –OUT2

13

11

12

10

S2

+V

OCM2

V

+OUT2

7429-006

Figure 5. ADA4939-1 Pin Configuration

Figure 6. ADA4939-2 Pin Configuration

Table 9. ADA4939-1 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 +V 9 V

S

OCM

Positive Supply Voltage

Output Common-Mode Voltage 10 +OUT Positive Output for Load Connection 11 −OUT Negative Output for Load Connection 12

PD

13 to 16 −V

S

Power-Down Pin

Negative Supply Voltage

Table 10. ADA4939-2 Pin Function Descriptions

Pin No. Mnemonic Description

1 −IN1 Negative Input Summing Node 1 2 +FB1 Positive Output Feedback 1 3, 4 +V

S1

Positive Supply Voltage 1 5 −FB2 Negative Output Feedback 2 6 +IN2 Positive Input Summing Node 2 7 −IN2 Negative Input Summing Node 2 8 +FB2 Positive Output Feedback 2 9, 10 +V 11 V

S2

OCM2

Positive Supply Voltage 2

Output Common-Mode Voltage 2 12 +OUT2 Positive Output 2 13 −OUT2 Negative Output 2 14

PD2 15, 16 −V 17 V

S2

OCM1

Power-Down Pin 2 Negative Supply Voltage 2

Output Common-Mode Voltage 1 18 +OUT1 Positive Output 1 19 −OUT1 Negative Output 1 20

PD1

21, 22 −V

S1

Power-Down Pin 1

Negative Supply Voltage 1 23 −FB1 Negative Output Feedback 1 24 +IN1 Positive Input Summing Node 1

Rev. 0 | Page 8 of 24

ANALOG DEVICES ADA4939-1, ADA4939-2 Service Manual

FEATURES

APPLICATIONS

GENERAL DESCRIPTION

FUNCTIONAL BLOCK DIAGRAMS

TABLE OF CONTENTS

REVISION HISTORY

SPECIFICATIONS

5 V OPERATION

General Performance

3.3 V OPERATION

General Performance

ABSOLUTE MAXIMUM RATINGS

THERMAL RESISTANCE

MAXIMUM POWER DISSIPATION

ESD CAUTION

PIN CONFIGURATIONS AND FUNCTION DESCRIPTIONS