MAX-3510EEP Maxim, MAX-3510EEP Datasheet - Page 10

• Manufacturer Part Number: MAX-3510EEP
• Description: Upstream CATV Amplifier
• Manufacturer: Maxim

The model for the MAX3510 input impedance is shown
in Figure 3.
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.
The differential implementation of the MAX3510’s out-
put has the benefit of significantly reducing even-order
distortion, the most significant of which is 2nd-harmonic
distortion. The degree of distortion cancellation
depends on the amplitude and phase balance of the
overall circuit. It is critical that the traces that lead from
the output pins be exactly the same length.
Upstream CATV Amplifier
Figure 3. Equivalent Input Circuit
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VIN+
VIN-
2k
Output Circuit Layout
1.1pF
Layout Issues
For minimal coupling between different sections of the
IC, the ideal power-supply layout is a star configuration.
This configuration has a large-value decoupling capac-
itor at the central power-supply node. The power-sup-
ply traces branch out from this node, each going to a
separate power-supply node in the MAX3510 circuit. At
the end of each of these traces is a decoupling capaci-
tor that provides a very low impedance at the frequen-
cy of interest. This arrangement provides local power-
supply decoupling at each power-supply pin.
The power supply traces must be made as thick as
practical to keep resistance well below 1Ω.
Ground inductance degrades distortion performance.
Therefore, ground plane connections to GND1 and
GND2 should be made with multiple vias if possible.
Power-Supply Layout