LMH6552SD/NOPB - NATIONAL SEMICONDUCTOR

LMH6552

LMH6552 1.5 GHz Fully Differential Amplifier

Literature Number: SNOSAX9G

LMH6552

July 19, 2011

1.5 GHz Fully Differential Amplifier

General Description

The LMH6552 is a high performance fully differential amplifier

designed to provide the exceptional signal fidelity and wide

large-signal bandwidth necessary for driving 8 to 14 bit high

speed data acquisition systems. Using National's proprietary

differential current mode input stage architecture, the

LMH6552 allows operation at gains greater than unity without

sacrificing response flatness, bandwidth, harmonic distortion,

or output noise performance.

With external gain set resistors and integrated common mode

feedback, the LMH6552 can be configured as either a differ-

ential input to differential output or single ended input to

differential output gain block. The LMH6552 can be AC or DC

coupled at the input which makes it suitable for a wide range

of applications including communication systems and high

speed oscilloscope front ends. The performance of the

LMH6552 driving an ADC14DS105 is 86 dBc SFDR and 74

dBc SNR up to 40 MHz.

The LMH6552 is available in an 8-pin SOIC package as well

as a space saving, thermally enhanced 8-Pin LLP package

for higher performance.

Features

■1.5 GHz −3 dB small signal bandwidth @ AV = 1

■1.25 GHz −3 dB large signal bandwidth @ AV = 1

■800 MHz bandwidth @ AV = 4

■450 MHz 0.1 dB flatness

■3800 V/µs slew rate

■10 ns settling time to 0.1%

■−90 dB THD @ 20 MHz

■−74 dB THD @ 70 MHz

■20 ns enable/shutdown pin

■5 to 12V operation

Applications

■Differential ADC driver

■Video over twisted pair

■Differential line driver

■Single end to differential converter

■High speed differential signaling

■IF/RF amplifier

■Level shift amplifier

■SAW filter buffer/driver

Typical Application

Single-Ended Input Differential Output ADC Driver

30003566

LMH™ is a trademark of National Semiconductor Corporation.

LMH6552 1.5 GHz Fully Differential Amplifier

Absolute Maximum Ratings (Note 1)

If Military/Aerospace specified devices are required,

please contact the National Semiconductor Sales Office/

Distributors for availability and specifications.

ESD Tolerance (Note 5)

Human Body Model 2000V

Machine Model 200V

Supply Voltage 13.2V

Common Mode Input Voltage ±VS

Maximum Input Current (pins 1, 2, 7, 8) 30 mA

Maximum Output Current (pins 4, 5) (Note 4)

Maximum Junction Temperature 150°C

Soldering Information

For soldering specifications

see product folder at www.national.com and

www.national.com/ms/MS/MS-SOLDERING.pdf

Operating Ratings (Note 1)

Operating Temperature Range

(Note 3) −40°C to +85°C

Storage Temperature Range −65°C to +150°C

Total Supply Voltage 4.5V to 12V

Package Thermal Resistance (θJA)

8-Pin SOIC 150°C/W

8-Pin LLP 58°C/W

±5V Electrical Characteristics (Note 2)

Unless otherwise specified, all limits are guaranteed for TA = 25°C, V+ = +5V, V− = −5V, AV= 1, VCM = 0V, RF = RG = 357Ω,

RL = 500Ω, for single ended in, differential out. Boldface limits apply at the temperature extremes.

Symbol Parameter Conditions Min

(Note 8)

Typ

(Note 7)

Max

(Note 8)Units

AC Performance (Differential)

SSBW Small Signal −3 dB Bandwidth

(Note 8)

VOUT = 0.2 VPP, AV = 1, RL = 1 kΩ 1500

MHz

VOUT = 0.2 VPP, AV = 1 1000

VOUT = 0.2 VPP, AV = 2 930

VOUT = 0.2 VPP, AV = 4 810

VOUT = 0.2 VPP, AV = 8 590

LSBW Large Signal −3 dB Bandwidth VOUT = 2 VPP, AV = 1, RL = 1 kΩ 1250

MHz

VOUT = 2 VPP, AV = 1 950

VOUT = 2 VPP, AV = 2 820

VOUT = 2 VPP, AV = 4 740

VOUT = 2 VPP, AV = 8 590

0.1 dB Bandwidth VOUT = 0.2 VPP, AV = 1 450 MHz

Slew Rate 4V Step, AV = 1 3800 V/μs

Rise/Fall Time, 10%-90% 2V Step 600 ps

0.1% Settling Time 2V Step 10 ns

Overdrive Recovery Time VIN = 1.8V to 0V Step, AV = 5 V/V 6 ns

Distortion and Noise Response

HD2 2nd Harmonic Distortion VOUT = 2 VPP, f = 20 MHz, RL = 800Ω −92

dBc

VOUT = 2 VPP, f = 70 MHz, RL = 800Ω −74

HD3 3rd Harmonic Distortion VOUT = 2 VPP, f = 20 MHz, RL = 800Ω −93

dBc

VOUT = 2 VPP, f = 70 MHz, RL = 800Ω −84

IMD3 Two-Tone Intermodulation f ≥ 70 MHz, Third Order Products, VOUT

= 2 VPP Composite

−87 dBc

Input Noise Voltage f ≥ 1 MHz 1.1 nV/

Input Noise Current f ≥ 1 MHz 19.5 pA/

Noise Figure (See Figure 5)50Ω System, AV = 9, 10 MHz 10.3 dB

Input Characteristics

IBI Input Bias Current (Note 10) 60 110 µA

IBoffset Input Bias Current Differential

(Note 7)

VCM = 0V, VID = 0V, IBoffset = (IB− - IB+)/2 2.5 18 µA

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LMH6552

Symbol Parameter Conditions Min

(Note 8)

Typ

(Note 7)

Max

(Note 8)Units

CMRR Common Mode Rejection Ratio

(Note 7)

DC, VCM = 0V, VID = 0V 80 dBc

RIN Input Resistance Differential 15 Ω

CIN Input Capacitance Differential 0.5 pF

CMVR Input Common Mode Voltage

Range

CMRR > 38 dB ±3.5 ±3.8 V

Output Performance

Output Voltage Swing (Note 7) Differential Output 14.8 15.4 VPP

IOUT Linear Output Current (Note 7) VOUT = 0V ±70 ±80 mA

ISC Short Circuit Current One Output Shorted to Ground VIN = 2V

Single Ended (Note 6)

±141 mA

Output Balance Error ΔVOUT Common Mode /ΔVOUT

Differential , ΔVOD = 1V, f < 1 MHz

−60 dB

Miscellaneous Performance

ZTOpen Loop Transimpedance Differential 108 dBΩ

PSRR Power Supply Rejection Ratio DC, (V+ - |V-|) = ±1V 80 dB

ISSupply Current (Note 7)RL = ∞19 22.5 25

28 mA

Enable Voltage Threshold 3.0 V

Disable Voltage Threshold 2.0 V

Enable/Disable time 15 ns

ISD Disable Shutdown Current 500 600 μA

Output Common Mode Control Circuit

Common Mode Small Signal

Bandwidth

VIN+ = VIN− = 0 400 MHz

Slew Rate VIN+ = VIN− = 0 607 V/μs

VOSCM Input Offset Voltage Common Mode, VID = 0, VCM = 0 1.5 ±16.5 mV

Input Bias Current (Note 9) −3.2 ±8 µA

Voltage Range ±3.7 ±3.8 V

CMRR Measure VOD, VID = 0V 80 dB

Input Resistance 200 kΩ

Gain ΔVO,CM/ΔVCM 0.995 1.0 1.012 V/V

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LMH6552

±2.5V Electrical Characteristics (Note 2)

Unless otherwise specified, all limits are guaranteed for TA = 25°C, V+ = +2.5V, V− = −2.5V, AV = 1, VCM = 0V, RF = RG = 357Ω,

RL = 500Ω, for single ended in, differential out. Boldface limits apply at the temperature extremes.

Symbol Parameter Conditions Min

(Note 8)

Typ

(Note 7)

Max

(Note 8)Units

SSBW Small Signal −3 dB Bandwidth

(Note 8)

VOUT = 0.2 VPP, AV = 1, RL = 1 kΩ 1100

MHz

VOUT = 0.2 VPP, AV = 1 800

VOUT = 0.2 VPP, AV = 2 740

VOUT = 0.2 VPP, AV = 4 660

VOUT = 0.2 VPP, AV = 8 498

LSBW Large Signal −3 dB Bandwidth VOUT = 2 VPP, AV = 1, RL = 1 kΩ 820

MHz

VOUT = 2 VPP, AV = 1 690

VOUT = 2 VPP, AV = 2 620

VOUT = 2 VPP, AV = 4 589

VOUT = 2 VPP, AV = 8 480

0.1 dB Bandwidth VOUT = 0.2 VPP, AV = 1 300 MHz

Slew Rate 2V Step, AV = 1 2100 V/μs

Rise/Fall Time, 10% to 90% 2V Step 700 ps

0.1% Settling Time 2V Step 10 ns

Overdrive Recovery Time VIN = 0.7 V to 0 V Step, AV = 5 V/V 6 ns

Distortion and Noise Response

HD2 2nd Harmonic Distortion VOUT = 2 VPP, f = 20 MHz, RL = 800Ω -82

dBc

VOUT = 2 VPP, f = 70 MHz, RL = 800Ω -65

HD3 3rd Harmonic Distortion VOUT = 2 VPP, f = 20 MHz, RL = 800Ω -79

dBc

VOUT = 2 VPP, f = 70 MHz, RL = 800Ω -67

IMD3 Two-Tone Intermodulation f ≥ 70 MHz, Third Order Products,

VOUT = 2 VPP Composite

−77 dBc

Input Noise Voltage f ≥ 1 MHz 1.1 nV/

Input Noise Current f ≥ 1 MHz 19.5 pA/

Noise Figure (See Figure 5)50Ω System, AV = 9, 10 MHz 10.2 dB

Input Characteristics

IBI Input Bias Current (Note 10) 54 90 µA

IBoffset Input Bias Current Differential

(Note 7)

VCM = 0V, VID = 0V, IBoffset = (IB− - IB+ )/2 2.3 18 μA

CMRR Common-Mode Rejection Ratio

(Note 7)

DC, VCM = 0V, VID = 0V 75 dBc

RIN Input Resistance Differential 15 Ω

CIN Input Capacitance Differential 0.5 pF

CMVR Input Common Mode Range CMRR > 38 dB ±1.0 ±1.3 V

Output Performance

Output Voltage Swing (Note 7) Differential Output 5.6 6.0 VPP

IOUT Linear Output Current (Note 7) VOUT = 0V ±55 ±65 mA

ISC Short Circuit Current One Output Shorted to Ground, VIN = 2V

Single Ended (Note 6)

±131 mA

Output Balance Error ΔVOUT Common Mode /ΔVOUT

Differential , ΔVOD = 1V, f < 1 MHz

60 dB

Miscellaneous Performance

ZT Open Loop Transimpedance Differential 107 dBΩ

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LMH6552

Symbol Parameter Conditions Min

(Note 8)

Typ

(Note 7)

Max

(Note 8)Units

PSRR Power Supply Rejection Ratio DC, ΔVS = ±1V 80 dB

ISSupply Current (Note 7)RL = ∞17 20.4 24

27 mA

Enable Voltage Threshold 3.0 V

Disable Voltage Threshold 2.0 V

Enable/Disable Time 15 ns

ISD Disable Shutdown Current 500 600 µA

Output Common Mode Control Circuit

Common Mode Small Signal

Bandwidth

VIN+ = VIN− = 0 310 MHz

Slew Rate VIN+ = VIN− = 0 430 V/μs

VOSCM Input Offset Voltage Common Mode, VID = 0, VCM = 0 1.65 ±15 mV

Input Bias Current (Note 9) −2.9 µA

Voltage Range ±1.19 ±1.25 V

CMRR Measure VOD, VID = 0V 80 dB

Input Resistance 200 kΩ

Gain ΔVO,CM/ΔVCM 0.995 1.0 1.012 V/V

Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is

intended to be functional, but specific performance is not guaranteed. For guaranteed specifications, see the Electrical Characteristics tables.

Note 2: Electrical Table values apply only for factory testing conditions at the temperature indicated. Factory testing conditions result in very limited self-heating

of the device such that TJ = TA. No guarantee of parametric performance is indicated in the electrical tables under conditions of internal self-heating where

TJ > TA. See Applications Section for information on temperature de-rating of this device." Min/Max ratings are based on product characterization and simulation.

Individual parameters are tested as noted.

Note 3: The maximum power dissipation is a function of TJ(MAX), θJA. The maximum allowable power dissipation at any ambient temperature is

PD = (TJ(MAX)– TA) / θJA. All numbers apply for packages soldered directly onto a PC Board.

Note 4: The maximum output current (IOUT) is determined by device power dissipation limitations. See the Power Dissipation section of the Application Section

for more details.

Note 5: Human Body Model, applicable std. MIL-STD-883, Method 30157. Machine Model, applicable std. JESD22-A115-A (ESD MM std. of JEDEC). Field-

Induced Charge-Device Model, applicable std. JESD22-C101-C (ESD FICDM std. of JEDEC).

Note 6: Short circuit current should be limited in duration to no more than 10 seconds. See the Power Dissipation section of the Application Information for more

details.

Note 7: Typical values represent the most likely parametric norm as determined at the time of characterization. Actual typical values may vary over time and will

also depend on the application and configuration. The typical values are not tested and are not guaranteed on shipped production material.

Note 8: Limits are 100% production tested at 25°C. Limits over the operating temperature range are guaranteed through correlation using Statistical Quality

Control (SQC) methods.

Note 9: Negative input current implies current flowing out of the device.

Note 10: IBI is referred to a differential output offset voltage by the following relationship: VOD(offset) = IBI*2RF

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LMH6552

Connection Diagrams

8-Pin SOIC

30003508

Top View

8-Pin LLP

30003564

Top View

Pin Descriptions

Pin No. Pin Name Description

1 -IN Negative Input

2 VCM Output Common Mode Control

3 V+ Positive Supply

4 +OUT Positive Output

5 -OUT Negative Output

6 V- Negative Supply

7 EN Enable

8 +IN Positive Input

DAP DAP Die Attach Pad (See Thermal Performance section for more information)

Ordering Information

Package Part Number Package Marking Transport Media NSC Drawing

8-Pin SOIC LMH6552MA LMH6552MA 95/Rails M08A

LMH6552MAX 2.5k Units Tape and Reel

8-Pin LLP LMH6552SD 6552 1k Units Tape and Reel SDA08C

LMH6552SDX 4.5k Units Tape and Reel

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LMH6552

Typical Performance Characteristics V+ = +5V, V− = −5V (TA = 25°C, RF = RG =

357Ω, RL = 500Ω, AV = 1, for single ended in, differential out, unless specified).

Frequency Response vs. Gain

30003547

Frequency Response vs. Gain

30003534

Frequency Response vs. VOUT

30003548

Frequency Response vs. VOUT

30003516

Frequency Response vs. Supply Voltage

30003562

Frequency Response vs. Supply Voltage

30003563

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LMH6552

Frequency Response vs. Capacitive Load

30003521

Suggested ROUT vs. Capacitive Load

30003522

Frequency Response vs. Resistive Load

30003559

Frequency Response vs. Resistive Load

30003560

Frequency Response vs. RF

30003561

1 VPP Pulse Response Single Ended Input

30003526

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LMH6552

2 VPP Pulse Response Single Ended Input

30003527

Large Signal Pulse Response

30003525

Output Common Mode Pulse Response

30003524

Distortion vs. Frequency Single Ended Input

30003529

Distortion vs. Supply Voltage

30003543

Distortion vs. Supply Voltage

30003537

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LMH6552

Distortion vs. Output Common Mode Voltage

30003538

Distortion vs. Output Common Mode Voltage

30003567

Maximum VOUT vs. IOUT

30003530

Minimum VOUT vs. IOUT

30003531

Open Loop Transimpedance

30003541

Open Loop Transimpedance

30003542

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LMH6552

Closed Loop Output Impedance

30003517

Closed Loop Output Impedance

30003518

Overdrive Recovery

30003557

Overdrive Recovery

30003558

PSRR

30003519

PSRR

30003520

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LMH6552

CMRR

30003533

Balance Error

30003513

Noise Figure

30003545

Noise Figure

30003546

Input Noise vs. Frequency

30003549

Differential S-Parameter Magnitude vs. Frequency

30003555

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LMH6552

Differential S-Parameter Phase vs. Frequency

30003556

3rd Order Intermodulation Products vs. VOUT

30003551

3rd Order Intermodulation Products vs. VOUT

30003552

3rd Order Intermodulation Products vs. Center Frequency

30003565

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LMH6552

Application Information

The LMH6552 is a fully differential current feedback amplifier

with integrated output common mode control, designed to

provide low distortion amplification to wide bandwidth differ-

ential signals. The common mode feedback circuit sets the

output common mode voltage independent of the input com-

mon mode, as well as forcing the V+ and V− outputs to be

equal in magnitude and opposite in phase, even when only

one of the inputs is driven as in single to differential conver-

sion.

The proprietary current feedback architecture of the

LMH6552 offers gain and bandwidth independence with ex-

ceptional gain flatness and noise performance, even at high

values of gain, simply with the appropriate choice of RF1 and

RF2. Generally RF1 is set equal to RF2, and RG1 equal to

RG2, so that the gain is set by the ratio RF/RG. Matching of

these resistors greatly affects CMRR, DC offset error, and

output balance. A minimum of 0.1% tolerance resistors are

recommended for optimal performance, and the amplifier is

internally compensated to operate with optimum gain flatness

with values of RF between 270Ω and 390Ω depending on

package selection, PCB layout, and load resistance.

The output common mode voltage is set by the VCM pin with

a fixed gain of 1 V/V. This pin should be driven by a low

impedance reference and should be bypassed to ground with

a 0.1 µF ceramic capacitor. Any unwanted signal coupling into

the VCM pin will be passed along to the outputs, reducing the

performance of the amplifier. This pin must not be left floating.

The LMH6552 can be operated on a supply range as either a

single 5V supply or as a split +5V and −5V. Operation on a

single 5V supply, depending on gain, is limited by the input

common mode range; therefore, AC coupling may be re-

quired. For example, in a DC coupled input application on a

single 5V supply, with a VCM of 1.5V, the input common volt-

age at a gain of 1 will be 0.75V which is outside the minimum

1.2V to 3.8V input common mode range of the amplifier. The

minimum VCM for this application should be greater than 2.5V

depending on output signal swing. Alternatively, AC coupling

of the inputs in this example results in equal input and output

common mode voltages, so a 1.5V VCM would be achievable.

Split supplies will allow much less restricted AC and DC cou-

pled operation with optimum distortion performance.

The LMH6552 is equipped with an ENABLE pin to reduce

power consumption when not in use. The ENABLE pin, when

not driven, floats high (on). When the ENABLE pin is pulled

low the amplifier is disabled and the amplifier output stage

goes into a high impedance state so the feedback and gain

set resistors determine the output impedance of the circuit.

For this reason input to output isolation will be poor in the

disabled state and the part is not recommended in multiplexed

applications where outputs are all tied together.

LLP PACKAGE

Due to it's size and lower parasitics, the LLP requires the low-

er optimum value of 275Ω for RF. This will give a flat frequency

response with minimal peaking. With a lower RF value the LLP

package will have a reduction in noise compared to the SOIC

with its optimum RF = 360Ω.

FULLY DIFFERENTIAL OPERATION

The LMH6552 will perform best in a fully differential configu-

ration. The circuit shown in Figure 1 is a typical fully differential

application circuit as might be used to drive an analog to dig-

ital converter (ADC). In this circuit the closed loop gain

AV = VOUT/ VIN = RF/RG, where the feedback is symmetric.

The series output resistors, RO, are optional and help keep

the amplifier stable when presented with a capacitive load.

Refer to the Driving Capacitive Loads section for details.

30003504

FIGURE 1. Typical Application

When driven from a differential source, the LMH6552 pro-

vides low distortion, excellent balance, and common mode

rejection. This is true provided the resistors RF, RG and RO

are well matched and strict symmetry is observed in board

layout. With an intrinsic device CMRR of 80 dB, using 0.1%

resistors will give a worst case CMRR of around 60 dB for

most circuits.

30003553

FIGURE 2. Differential S-Parameter Test Circuit

The circuit configuration shown in Figure 2 was used to mea-

sure differential S parameters in a 50Ω environment at a gain

of 1 V/V. Refer to the Differential S-Parameter vs. Frequency

plots in the Typical Performance Characteristics section for

measurement results.

SINGLE ENDED INPUT TO DIFFERENTIAL OUTPUT

OPERATION

In many applications, it is required to drive a differential input

ADC from a single ended source. Traditionally, transformers

have been used to provide single to differential conversion,

but these are inherently bandpass by nature and cannot be

used for DC coupled applications. The LMH6552 provides

excellent performance as a single-to-differential converter

down to DC. Figure 3 shows a typical application circuit where

an LMH6552 is used to produce a differential signal from a

single ended source.

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LMH6552