Single/Dual/Quad, 270MHz, 1mA, SOT23,

Current-Feedback Amplifiers with Shutdown

______________________________________________________________________________________

19

tive load. Note that in each case, gain peaking is

substantially reduced when the 20

Ω resistor is used to

isolate the capacitive load from the amplifier output.

AC Testing/Performance

AC specifications on high-speed amplifiers are usually

guaranteed without 100% production testing. Since

these high-speed devices are sensitive to external para-

sitics introduced when automatic handling equipment is

used, it is impractical to guarantee AC parameters

through volume production testing. These parasitics are

greatly reduced when using the recommended PC

board layout (like the Maxim EV kit). Characterizing the

part in this way more accurately represents the amplifi-

er’s true AC performance. Some manufacturers guaran-

tee AC specifications without clearly stating how this

guarantee is made. The AC specifications of the

MAX4180–MAX4187 are derived through worst-case

design simulations combined with a sample characteri-

zation of 100 units. The AC performance distributions

along with the worst-case simulation results for

MAX4180 and MAX4181 are shown in Figures 8–11.

These distributions are repeatable provided that the

proper board layout and power-supply bypassing are

used (see

Layout and Power-Supply Bypassing sec-

tion).

6

5

4

3

2

1

0

-4

1

10

100

1000

-2

-3

-1

FREQUENCY (MHz)

MAX4181

RS = 20

Ω

RS = 0

Ω

Figure 7c. Frequency Response with Capacitive Load (with

and without Isolation Resistor)

Figure 7b. Frequency Response with Capacitive Load (with

and without Isolation Resistor)

6

5

4

3

2

1

0

-4

1

10

100

1000

-2

-3

-1

FREQUENCY (MHz)

MAX4180

Loads