+

-

51:

X1

-

+

51:

CL

10 pF

1 k:

+

-

+5V

-5V

6.8 µF

0.01 µF

6.8 µF

0.01 µF

0.1 µF

1

1000

FREQUENCY (MHz)

-8

-4

0

4

100

10

-2

-6

-7

-5

-3

-1

1

2

3

GAIN = +1

PIN 4 FLOATING

PIN 4 SHORTED TO PIN 3

1

10

1000

FREQUENCY (MHz)

100

-8

-4

0

4

2

-2

-6

3

1

-1

-3

-5

-7

UNCOMPENSATED

+

-

50:

100:

50:

3.3 pF

LMH6739

SNOSAD2G – MAY 2004 – REVISED MARCH 2013

www.ti.com

from part to part.

Figure 24. Correction for Unity Gain Peaking

Figure 25. Frequency Response for Circuit in

Figure 24

UNITY GAIN COMPENSATION

With a current feedback Selectable Gain Buffer like the LMH6739, the feedback resistor is a compromise

between the value needed for stability at unity gain and the optimized value used at a gain of two. The result of

this compromise is substantial peaking at unity gain. If this peaking is undesirable a simple RC filter at the input

of the buffer will smooth the frequency response shown as Figure 24. Figure 25 shows the results of a simple

filter placed on the non-inverting input. See Figure 26 and Figure 27 for another method for reducing unity gain

peaking.

Figure 26. Alternate Unity Gain Compensation

Figure 27. Frequency Response for Circuit in

Figure 26

Figure 28. Decoupling Capacitive Loads

10

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