9

LT1363

The LT1363 may be inserted directly into AD817, AD847,

EL2020, EL2044, and LM6361 applications improving

both DC and AC performance, provided that the nulling

circuitry is removed. The suggested nulling circuit for the

LT1363 is shown below.

Offset Nulling

1363 AI01

6

7

4

8

1

2

10k

3

–

+

LT1363

Layout and Passive Components

The LT1363 amplifier is easy to apply and tolerant of less

than ideal layouts. For maximum performance (for ex-

ample fast settling time) use a ground plane, short lead

lengths, and RF-quality bypass capacitors (0.01

µF to

0.1

µF). For high drive current applications use low ESR

bypass capacitors (1

µF to 10µF tantalum). Sockets

should be avoided when maximum frequency perfor-

mance is required, although low profile sockets can

provide reasonable performance up to 50MHz. For

more details see Design Note 50.

The parallel combination of the feedback resistor and gain

setting resistor on the inverting input can combine with

the input capacitance to form a pole which can cause

peaking or oscillations. For feedback resistors greater

than 5k

Ω, a parallel capacitor of value

should be used to cancel the input pole and optimize

dynamic performance. For unity-gain applications where

Capacitive Loading

The LT1363 is stable with any capacitive load. This is

accomplished by sensing the load induced output pole and

adding compensation at the amplifier gain node. As the

capacitive load increases, both the bandwidth and phase

margin decrease so there will be peaking in the frequency

domain and in the transient response as shown in the

typical performance curves.The photo of the small-signal

response with 200pF load shows 62% peaking. The large-

signal response with a 10,000pF load shows the output

slew rate being limited to 10V/

µs by the short-circuit

current. Coaxial cable can be driven directly, but for best

pulse fidelity a resistor of value equal to the characteristic

impedance of the cable (i.e., 75

Ω) should be placed in

series with the output. The other end of the cable should

be terminated with the same value resistor to ground. The

response of a cable driver in a gain of 2 driving a 75

Ω cable

is shown on the front page of the data sheet.

Large-Signal Transient

Large-Signal Transient

Large-Signal Transient

1363 TA34

1363 TA35

1363 TA36