LMH6552SDEVAL National Semiconductor, LMH6552SDEVAL Datasheet

LMH6552SDEVAL

Manufacturer Part Number

LMH6552SDEVAL

Description

BOARD EVALUATION FOR LMH6552

Manufacturer

National Semiconductor

Series

LMH®, PowerWise®r

Datasheets

1.LMH6552SDEVAL.pdf (22 pages)

2.LMH6552SDEVAL.pdf (4 pages)

3.LMH6552SDEVAL.pdf (20 pages)

Specifications of LMH6552SDEVAL

Channels Per Ic

1 - Single

Amplifier Type

Differential

Output Type

Differential

Slew Rate

3800 V/µs

-3db Bandwidth

1.5GHz

Current - Output / Channel

80mA

Operating Temperature

-40°C ~ 85°C

Current - Supply (main Ic)

22.5mA

Voltage - Supply, Single/dual (±)

4.5 V ~ 12 V, ±2.25 V ~ 6 V

Board Type

Fully Populated

Utilized Ic / Part

LMH6552

Lead Free Status / RoHS Status

Contains lead / RoHS non-compliant

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LMH6552SDEVAL High

Speed Differential Amplifier

Evaluation Board

General Description

The LMH6552SDEVAL evaluation board is designed to aid in

the characterization of National Semiconductor’s LMH6552

fully differential amplifier in an 8-pin LLP package. The

LMH6552 is part of the LMH

Use the evaluation board as a guide for high frequency layout

and as a tool to aid in device testing and characterization.

The evaluation board schematic is shown below in Figure 1.

Refer to the product datasheets for recommended for com-

ponent values.

Basic Operation

The LMH6552SDEVAL evaluation board has been set up to

provide maximum flexibility for evaluating National’s differen-

tial LMH6552 operational amplifier. The board supports fully

differential operation as well as single-ended to differential

and single-ended to single-ended operation. For fully differ-

ential operation, use resistors R

impedance of the amplifier. Input resistance will be equal to

2*R

= R

input mode of operation, the input and termination resistance

must be properly configured to give the correct gain and R

For example, in the case of the LMH6552, if a gain of 2 V/V

is desired, R

node of R

input mode calculations for the LMH6552 can be found in the

datasheet. Components R

for AC-couple applications otherwise can be left empty.

For differential output applications, load R

desired values to match the output load and leave R

If single-ended output is desired leave R

load R

ADT4-1WT from Mini Circuits. The ADT4-1WT has a 4:1

impedance ratio (2:1 turns/voltage ratio). This is particularly

useful for interfacing to 50Ω test equipment. When referenc-

ing the transformer datasheet, the 980600016 evaluation

board has the primary windings on the output side of the eval-

uation board and the amplifier is driving the secondary wind-

ings. This provides a step down transformation from the

differential amplifier output to the test equipment. The center-

tapped secondary winding also allows a differential to single

LMH

, R

= 68.1Ω. Which will make R

empty.

is a registered trademark of National Semiconductor Corporation.

|| 2*R

, R

= R

, R

and R

. Where R

looking into R

= 28.7Ω, R

where R

and an output transformer such as the

set the gain of the amplifier. Amplifier gain

= R

and R

. Further details of single-ended

, R

high speed amplifier family.

and R

= 127Ω, R

, C

= 50Ω at the most positive

= R

, and C

and R

= R

. In this mode resistors

300334

and R

. For single-ended

= R

to set the input

and R

should be used

= 275Ω, and

empty and

with the

and

National Semiconductor

Application Note 1743

Vannavong Philavanh

June 20, 2008

ended conversion (Balun). The impedance seen by the dif-

ferential amplifier = (R

impedance from pin 3 of the transformer to the load.

Pin 7 on the LMH6552 device is the enable (EN) pin that can

be used to disable the device with an external signal. Refer

to LMH6552 datasheet for more details.

Layout Considerations

Printed circuit board layout and supply bypassing play major

roles in determining high frequency performance. When de-

signing your own board use these evaluation boards as a

guide and follow these steps to optimize high frequency per-

formance:

Sample artwork for the LMH6552SDEVAL ™ Evaluation

board is included on the next page in Figure 2.

Measurement Hints

Balance, CMRR and HD2 are highly dependent on resistor

matching. Use 0.1 or 0.01% resistors.

The LMH6552SDEVAL evaluation board is designed for dif-

ferential or single-ended output measurements, but not both

at the same time. When not using the transformer make sure

to leave R

ended output measurements leave R

Many differential amplifiers are optimized for the higher

impedances represented by most ADCs.

On a differential amplifier both inputs are inverting, keep par-

asitic capacitance to a minimum on both inputs. Also, using

probes of any kind on a differential circuit is not recommend-

ed.

Symmetry is of the utmost importance.

Use precision resistors 0.1% or 0.01%.

Use a ground plane.

Include large ( ~ 10 μF) capacitors on both supplies (C

and C

Near the device use 0.01 μF ceramic capacitors from

both supplies to ground (C

A capacitor between V

help lower distortion.

Remove the ground and power planes from under and

around the part, especially the input and output pins.

Minimize all trace lengths.

Use terminated transmission lines for long traces.

and R

empty. Likewise, when making single-

+ R

and V

, C

+ R

−

*4), where R

) is optional, but will

and R

www.national.com

empty.

is the

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LMH6552SDEVAL Summary of contents

Page 1

... LMH6552SDEVAL High Speed Differential Amplifier Evaluation Board General Description The LMH6552SDEVAL evaluation board is designed to aid in the characterization of National Semiconductor’s LMH6552 fully differential amplifier in an 8-pin LLP package. The LMH6552 is part of the LMH ® high speed amplifier family. Use the evaluation board as a guide for high frequency layout and as a tool to aid in device testing and characterization ...

Page 2

T1 = Mini Circuits ADT4-1WT www.national.com FIGURE 1. Board Schematic 2 30033403 ...

Page 3

FIGURE 2. Board Layout 3 30033401 www.national.com ...

Page 4

... For more National Semiconductor product information and proven design tools, visit the following Web sites at: Products Amplifiers www.national.com/amplifiers Audio www.national.com/audio Clock Conditioners www.national.com/timing Data Converters www.national.com/adc Displays www.national.com/displays Ethernet www.national.com/ethernet Interface www.national.com/interface LVDS www.national.com/lvds Power Management www.national.com/power Switching Regulators www.national.com/switchers LDOs www ...

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