LMH6718 datasheet(10/16 Pages) NSC

10 / 16 page

Typical Performance Characteristics (A

V = +2, RL = 100

Ω, Unless Specified). (Continued)

Differential Gain & Phase

Input Referred Crosstalk

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Application Section

LMH6718 OPERATION

The LMH6718 is a current feedback buffer fabricated in an

advanced complementary bipolar process. The LMH6718

operates from a single 5V supply or dual ±5V supplies.

Operating from a single 5V supply, the LMH6718 has the

following features:

•

Gains of ±1, −1, and 2V/V are achievable without exter-

nal resistors

•

Provides 170mA of output current

•

Offers low −88/−91dBc 2nd & 3rd harmonic distortion

•

Provides BW > 110MHz

The LMH6718 performance is further enhanced in ±5V sup-

ply applications as indicated in the ±5V Electrical Charac-

teristics table and the ±5V Typical Performance plots.

LMH6718 DESIGN INFORMATION

CLOSED LOOP GAIN SELECTION

The LMH6718 is a current feedback op amp with R

F =RG =

Ω on chip (in the package). Select from three closed loop

gains without using any external gain or feedback resistors.

Implement gains of +2, +1, and −1V/V by connecting pins 2

and 3 (or 5 and 6) as described in the chart below.

Gain A

Input Connections

Non-Inverting (pins 3,

Inverting (pins 2, 6)

−1V/V

ground

input signal

+1V/V

input signal

NC (open)

+2V/V

input signal

ground

The gain accuracy of the LMH6718 is excellent and stable

over temperature change. The internal gain setting resistors,

F and RG are poly silicon resistors. Although their absolute

values change with processing and temperature, their ratio

F/RG) remains constant. If an external resistor is used in

series with R

G, gain accuracy over temperature will suffer.

SINGLE SUPPLY OPERATION (V

CC = +5V, VEE = GND)

The specifications given in the +5V Electrical Characteris-

tics table for single supply operation are measured with a

common mode voltage (V

CM) of 2.5V. VCM is the voltage

around which the inputs are applied and the output voltages

are specified.

Operating from a single +5V supply, the Common Mode

Voltage Range (CMVR) of the LMH6718 is typically +0.8V to

+4.2V. The typical output range with R

L = 100

Ω is +1.0V to

+4.0V.

For single supply DC coupled operation, keep input signal

levels above 0.8V DC, AC coupling and level shifting the

signal are recommended. The non-inverting and inverting

configurations for both input conditions are illustrated in the

following 2 sections.

DC COUPLED SINGLE SUPPLY OPERATION

Figure 1, Figure 2, and Figure 3 on the following page, show

the recommended configurations for input signals that re-

main above 0.8V DC.

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FIGURE 1. DC Coupled, A

V = −1V/V Configuration

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