7

LT1208/LT1209

S

APPLICATI

I FOR ATIO

Input Considerations

Resistors in series with the inputs are recommended for

the LT1208/LT1209 in applications where the differential

input voltage exceeds

±6V continuously or on a transient

basis. An example would be in noninverting configura-

tions with high input slew rates or when driving heavy

capacitive loads. The use of balanced source resistance at

each input is recommended for applications where DC

accuracy must be maximized.

Transient Response

The LT1208/LT1209 gain-bandwidth is 45MHz when mea-

sured at 100kHz. The actual frequency response in unity-

gain is considerably higher than 45MHz due to peaking

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Small-Signal Capacitive Loading

Large-Signal Capacitive Loading

caused by a second pole beyond the unity-gain crossover.

This is reflected in the 50

° phase margin and shows up as

overshoot in the unity-gain small-signal transient re-

sponse. Higher noise gain configurations exhibit less

overshoot as seen in the inverting gain of one response.

The large-signal response in both inverting and non-

inverting gain show symmetrical slewing characteristics.

Normally the noninverting response has a much faster

rising edge due to the rapid change in input common-

mode voltage which affects the tail current of the input

differential pair. Slew enhancement circuitry has been

added to the LT1208/LT1209 so that the falling edge slew

rate is balanced.

Small-Signal Transient Response

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Small-Signal Transient Response