ada4950-1 Analog Devices, Inc., ada4950-1 Datasheet - Page 23

• Manufacturer Part Number: ada4950-1
• Description: Low Power, Selectable Gain Differential Adc Driver, G = 1, 2, 3
• Manufacturer: Analog Devices, Inc.

LAYOUT, GROUNDING, AND BYPASSING
As a high speed device, the ADA4950-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 ADA4950-x as possible. The
thermal resistance, θ
exposed pad, soldered to a high thermal conductivity 4-layer
circuit board, as described in EIA/JESD51-7.
Bypass the power supply pins as close to the device as possible
and directly to a nearby ground plane. Use high frequency
ceramic chip capacitors. 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. Farther away,
provide low frequency bulk bypassing using 10 μF tantalum
capacitors from each supply to ground.
Figure 62. Cross-Section of 4-Layer PCB Showing Thermal Via Connection to Buried Ground Plane (Dimensions in Millimeters)
JA
, is specified for the device, including the
GROUND PLANE
BOTTOM METAL
POWER PLANE
TOP METAL
Rev. 0 | Page 23 of 28
VIA HOLE
PLATED
1.30
0.30
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 61. Recommended PCB Thermal Attach Pad (Dimensions in Millimeters)
1.30
0.80
ADA4950-1/ADA4950-2
1.30
0.80