400MHz, Ultra-Low-Distortion Op Amps

10

______________________________________________________________________________________

12

-8

-6

0.1

1

100

10

1000

0

FREQUENCY (MHz)

6

10

-2

-4

2

4

8

Figure 2a. MAX4108 Response vs. Capacitive Load—No

20

0

0.1

1

100

10

1000

8

FREQUENCY (MHz)

14

18

2

6

4

10

12

16

Figure 2b. MAX4109 Response vs. Capacitive Load—No

4

-6

-5

0.1

1

100

10

1000

-2

FREQUENCY (MHz)

1

3

-3

-4

-1

0

2

Figure 2c. MAX4308 Response vs. Capacitive Load—No

4

-6

-5

0.1

1

100

10

1000

-2

FREQUENCY (MHz)

1

3

-3

-4

-1

0

2

Figure 2d. MAX4309 Response vs. Capacitive Load—No

Driving Capacitive Loads

The MAX4108/MAX4109/MAX4308/MAX4309 are opti-

mized for AC performance. They are not designed to

drive highly reactive loads. Reactive loads will

decrease phase margin and may produce excessive

ringing and oscillation. Figure 1a shows a circuit that

eliminates this problem, and Figure 1b is a graph of the

Figures 2a–2d show how a capacitive load causes

excessive peaking of the amplifier’s bandwidth if the

small isolation resistor (usually 15

Ω to 22Ω) placed