THS4509-Q1 Datasheet, PDF (30/40 Pages) Texas Instruments – WIDEBAND LOW-NOISE LOW-DISTORTION FULLY DIFFERENTIAL AMPLIFIER

THS4509-Q1
SLOS547 – NOVEMBER 2008........................................................................................................................................................................................... www.ti.com
Layout Recommendations
It is recommended to follow the layout of the external
components near the amplifier, ground plane
construction, and power routing of the EVM as
closely as possible. General guidelines are:
1. Signal routing should be direct and as short as
possible into and out of the op amp 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-µF and two 0.1-µF power-supply
decoupling capacitors should be placed as near
to the power-supply pins as possible.
6. Two 0.1-µF 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) and to use a solid ground on layer 3
(L3). A single-point connection should be used
between each split section on L2 and L3.
8. A single-point connection to ground on L2 is
recommended for the input termination resistors
R1 and R2. This should be applied to the input
gain resistors if termination is not used.
9. The THS4509 recommended PCB footprint is
shown in Figure 92.
0.144
0.049
Pin 1
0.0095
0.015
0.144
0.012
0.0195 0.0705
0.032
0.010
vias
0.030
0.0245
Top View
Figure 92. QFN Etch and Via Pattern
30
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