ada4932 Analog Devices, Inc., ada4932 Datasheet - Page 24

• Manufacturer Part Number: ada4932
• Description: Low Power Differential Adc Driver
• Manufacturer: Analog Devices, Inc.

ADA4932-1/ADA4932-2
LAYOUT, GROUNDING, AND BYPASSING
As a high speed device, the ADA4932-x is sensitive to the
PCB environment in which it operates. Realizing its superior
performance requires attention to the details of high speed
PCB design.
The first requirement is a solid ground plane that covers as much
of the board area around the ADA4932-x as possible. However,
the area near the feedback resistors (R
the input summing nodes (Pin 2 and Pin 3) should be cleared of
all ground and power planes (see Figure 64). Clearing the ground
and power planes minimizes any stray capacitance at these nodes
and thus minimizes peaking of the response of the amplifier at
high frequencies.
The thermal resistance, θ
the exposed pad, soldered to a high thermal conductivity 4-layer
circuit board, as described in EIA/JESD51-7.
Figure 64. Ground and Power Plane Voiding in Vicinity of R
Figure 66. Cross-Section of 4-Layer PCB Showing Thermal Via Connection to Buried Ground Plane (Dimensions in Millimeters)
JA
, is specified for the device, including
GROUND PLANE
BOTTOM METAL
POWER PLANE
TOP METAL
F
), gain resistors (R
F
and R
G
), and
G
Rev. 0 | Page 24 of 28
VIA HOLE
PLATED
1.30
0.30
Bypass the power supply pins as close to the device as possible
and directly to a nearby ground plane. High frequency ceramic
chip capacitors should be used. It is recommended that two
parallel bypass capacitors (1000 pF and 0.1 µF) be used for each
supply. Place the 1000 pF capacitor closer to the device. Further
away, provide low frequency bulk bypassing using 10 µF tantalum
capacitors from each supply to ground.
Signal routing should be short and direct to avoid parasitic effects.
Wherever complementary signals exist, provide a symmetrical
layout to maximize balanced performance. When routing
differential signals over a long distance, keep PCB traces close
together, and twist any differential wiring to minimize loop
area. Doing this reduces radiated energy and makes the circuit
less susceptible to interference.
Figure 65. Recommended PCB Thermal Attach Pad Dimensions (Millimeters)
1.30
0.80
1.30
0.80