Data Sheet

ADA4932-1/ADA4932-2

LAYOUT, GROUNDING, AND BYPASSING

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Rev. F | 26 of 27

As a high speed device, the ADA4932-1/ADA4932-2 are 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 ADA4932-1/ADA4932-2 as possible.

However, the area near the feedback resistors (RF), gain resistors

(RG), and clear the input summing nodes (Pin 2 and Pin 3) of all

ground and power planes (see Figure 66). 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, θJA, is specified for the device, including

the exposed pad, soldered to a high thermal conductivity 4-layer

circuit board, as described in EIA/JESD51-7.

Figure 66. Ground and Power Plane Voiding in Vicinity of RF and RG

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 to use two parallel bypass

capacitors (1000 pF and 0.1 µF) 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.

Ensure that signal routing is short and direct to avoid parasitic

effects. Wherever complementary signals exist, provide a symmetri-

cal layout to maximize balanced performance. When routing differ-

ential 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 67. Recommended PCB Thermal Attach Pad Dimensions (Millimeters)

Figure 68. Cross-Section of 4-Layer PCB Showing Thermal Via Connection to Buried Ground Plane (Dimensions in Millimeters)