9

LT1192

Closed-Loop Voltage Gain vs Frequency

Small-Signal Transient Response

Output Shutdown

FREQUENCY (Hz)

24

1G

LT1192 • TA10

100M

10M

1M

100k

22

20

18

16

14

12

10

APPLICATIO S I FOR ATIO

LT1192 • TA08

1MHz SINE WAVE GATED OFF WITH

LT1192 • TA09

–5V

0V

The ability to maintain shutoff is shown on the curve

Shutdown Supply Current vs Temperature in the Typical

Performance Characteristics section. At very high

elevated temperatures it is important to hold the SHDN pin

close to the negative supply to keep the supply current

from increasing.

Operating with Low Closed-Loop Gains

When using decompensated amplifiers it should be real-

ized that peaking in the frequency domain, and overshoot

and ringing in the time domain occur as closed-loop gain

is lowered. The LT1192 is stable to a closed-loop gain of

5, however, peaking and ringing can be minimized by

increasing the closed-loop gain. For instance, the LT1192

peaks 5dB when used in a gain of 5, but peaks by less than

0.5dB for a closed-loop gain of 10. Likewise, the overshoot

drops from 50% to 4% for gains of 10.

Murphy Circuits

There are several precautions the user should take when

using the LT1192 in order to realize its full capability.

Although the LT1192 can drive a 50pF load, isolating the

capacitance with 20

Ω can be helpful. Precautions prima-

rily have to do with driving large capacitive loads.

Other precautions include:

1. Use a ground plane (see Design Note 50, High Fre-

quency Amplifier Evaluation Board).

2. Do not use high source impedances. The input capaci-

8MHz – 3dB bandwidth.

3. PC board socket may reduce stability.

4. A feedback resistor of 1k or lower reduces the effects of

stray capacitance at the inverting input.