__________Applications Information

Grounding, Bypassing,

and PC Board Layout

To obtain the MAX4137/MAX4138’s full 185MHz band-

width, Microstrip and Stripline techniques are recom-

mended in most cases. To ensure the PC board does

not degrade the amplifier’s performance, design the

board for a frequency greater than 1GHz. Even with

very short traces, use these techniques at critical

points, such as inputs and outputs. Whether you use a

constant-impedance board or not, observe the follow-

ing guidelines when designing the board:

• Do not use wire-wrap boards. They are too inductive.

• Do not use IC sockets. They increase parasitic

capacitance and inductance.

• In general, surface-mount components have shorter

leads and lower parasitic reactance, giving better

high-frequency performance than through-hole com-

ponents.

• The PC board should have at least two layers, with

one side a signal layer and the other a ground plane.

• Keep signal lines as short and straight as possible.

Do not make 90° turns; round all corners.

• The ground plane should be as free from voids as

possible.

1-Input/4-Output

Video Distribution Amplifiers

8

_______________________________________________________________________________________

N.C.

1

VCCO

2

OUT1

3

OUT2

5

OUT3

8

GND

9

OUT4

10

VCCO

11

N.C.

12

OUT1

OUT2

OUT3

OUT4

MAX4137

SW1

SW2

SW3

SW4

GND

4

AGND

21

IN+

20

VEEI

19

AGND

18

N.C.

17

VCCI

16

SEL3

15

SEL4

14

N.C.

13

0.1

µF

0.1

µF

0.1

µF

0.1

µF

75

Ω*

75

Ω*

75

Ω*

75

Ω*

75

Ω*

75

Ω∗

VEEO

6

VEEO

7

0.1

µF

N.C.

24

SEL1

23

SEL2

22

VIDEO

IN

* TO TERMINATE TRANSMISSION LINE

IN

Figure 1. MAX4137 Typical Operating Circuit