MAX3532 データシートの表示（PDF） - Maxim Integrated

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MAX3532

Upstream CATV Driver Amplifier

Maxim Integrated 

Upstream CATV Driver Amplifier

Some allowance must be made for parasitic inductance

in the transformer as well as on the printed circuit

board. Therefore, choose a resistance value lower than

a perfect match. Two 8.0Ω resistors will provide a near-

optimum match.

If the output match is less than critical, the back-termina-

tion resistors can be set to a lower value. This will extend

the upper limit of the output level range (by dropping less

voltage across the resistors and more across the load),

and may improve distortion performance for a given out-

put level.

Layout Issues

A well designed printed circuit board is an essential

part of an RF circuit. For best performance pay atten-

tion to power-supply layout issues, as well the output

circuit layout.

Output Circuit Layout

The differential implementation of the MAX3532’s out-

put has the benefit of significantly reducing even-order

distortion, the most significant of which is second-har-

monic distortion. The degree of distortion cancellation

depends on the amplitude and phase balance of the

overall circuit. It is critical that the traces leading from

the output pins be exactly the same length.

Since the MAX3532 has a low-impedance output, the

output traces must also be kept as short as possible,

as small amounts of inductance can have an impact at

higher frequencies. The back-termination resistors

should be kept as close to the device as possible.

Power-Supply Layout

For minimal coupling between different sections of the

IC, the ideal power-supply layout is a star configuration.

This configuration has a large valued decoupling

capacitor at the central VCC node. The VCC traces

branch out from this node, each going to a separate

VCC node in the MAX3532 circuit. At the end of each of

these traces is a decoupling capacitor that provides a

very low impedance at the frequency of interest. This

arrangement provides local VCC decoupling at each

VCC pin.

The traces leading from the supply to VCC (pin 29) and

VCC2 (pin 30) must be made as thick as practical to

keep resistance well below 1Ω.

Ground inductance degrades distortion performance.

Therefore, ground plane connections to VEE (pin 26)

and VEE2 (pin 31) should be made with multiple vias if

possible.

Chip Information

TRANSISTOR COUNT: 1100

________________________________________________________Package Information

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