Low-Power, +3V/+5V, 400MHz Single-Supply

Op Amps with Rail-to-Rail Outputs

16

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Coaxial cable and other transmission lines are easily

driven when properly terminated at both ends with their

characteristic impedance. Driving back-terminated

transmission lines essentially eliminates the line’s

capacitance.

___________Applications Information

Choosing Resistor Values

Unity-Gain Configuration

The MAX4414/MAX4416/MAX4418 are internally com-

pensated for unity gain. When configured for unity gain,

the devices require a 24

resistor improves AC response by reducing the Q of the

parallel LC circuit formed by the parasitic feedback

capacitance and inductance.

Inverting and Noninverting Configurations

resistor values that best fit the application. Large resis-

tor values increase voltage noise and interact with the

amplifier’s input and PC board capacitance. This can

generate undesirable poles and zeros and decrease

bandwidth or cause oscillations. For example, a nonin-

Ω

resistors, combined with 1.8pF of amplifier input capac-

itance and 1pF of PC board capacitance, causes a

pole at 114MHz. Since this pole is within the amplifier

bandwidth, it jeopardizes stability. Reducing the 1k

Ω

resistors to 100

Ω extends the pole frequency to

1.14GHz, but could limit output swing by adding 200

Ω

in parallel with the amplifier’s load resistor.

Note: For high gain applications where output offset

R

RR

RR

S

FG

FG

=

×

+

IN

Figure 3a. Noninverting Gain Configuration

IN

Figure 3b. Inverting Gain Configuration

Figure 1. Driving a Capacitive Load Through an Isolation

Resistor

Figure 2. Capacitive Load vs. Isolation Resistance

10

16

14

12

18

20

22

24

26

28

30

0

400

200

600

800

1000