Datasheet

Layout Recommendations
0.144
0.0195
0.144
0.010
vias
Pin 1
Top View
0.012
0.030
0.0705
0.015
0.0095
0.049
0.032
0.0245
THS4508
www.ti.com .................................................................................................................................... SLAS459E – SEPTEMBER 2005 – REVISED SEPTEMBER 2008
and L3.
8. A single-point connection to ground on L2 is
It is recommended to follow the layout of the external
recommended for the input termination resistors
components near the amplifier, ground plane
R1 and R2. This should be applied to the input
construction, and power routing of the EVM as
gain resistors if termination is not used.
closely as possible. General guidelines are:
9. The THS4508 recommended printed circuit board
1. Signal routing should be direct and as short as
(PCB) footprint is shown in Figure 61 .
possible into and out of the operational amplifier
circuit.
2. The feedback path should be short and direct
avoiding vias.
3. Ground or power planes should be removed from
directly under the amplifier ’ s input and output
pins.
4. An output resistor is recommended on each
output, as near to the output pin as possible.
5. Two 10- µ F and two 0.1- µ F power-supply
decoupling capacitors should be placed as near
to the power-supply pins as possible.
6. Two 0.1- µ F capacitors should be placed between
the CM input pins and ground. This limits noise
coupled into the pins. One each should be placed
to ground near pin 4 and pin 9.
7. It is recommended to split the ground pane on
layer 2 (L2) as shown below and to use a solid
ground on layer 3 (L3). A single-point connection
Figure 61. QFN Etch and Via Pattern
should be used between each split section on L2
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