ADA4077-2

Data Sheet

Rev. 0 | Page 18 of 20

PROPER BOARD LAYOUT

The ADA4077-2 is a high precision device. To ensure optimum

performance at the PCB level, care must be taken in the design

of the board layout.

To avoid leakage currents, maintain a clean and moisture-free

board surface. Coating the surface creates a barrier to moisture

accumulation and helps reduce parasitic resistance on the board.

Keeping supply traces short and properly bypassing the power

supplies minimizes power supply disturbances caused by output

current variation, such as when driving an ac signal into a heavy

load. Connect bypass capacitors as closely as possible to the

device supply pins. Stray capacitances are a concern at the

outputs and the inputs of the amplifier. It is recommended that

signal traces be kept at least 5 mm from supply lines to

minimize coupling.

A variation in temperature across the PCB can cause a

mismatch in the Seebeck voltages at solder joints and other

points where dissimilar metals are in contact, resulting in

thermal voltage errors. To minimize these thermocouple effects,

orient resistors so heat sources warm both ends equally. Input

signal paths should contain matching numbers and types of

components, where possible, to match the number and type of

thermocouple junctions. For example, dummy components

such as zero value resistors can be used to match real resistors

in the opposite input path. Place matching components in close

proximity to each other and orient them in the same manner.

Ensure that leads are of equal length so that thermal conduction

is in equilibrium. Keep heat sources on the PCB as far away

from amplifier input circuitry as is practical.

The use of a ground plane is highly recommended. A ground

plane reduces EMI noise and helps to maintain a constant

temperature across the circuit board.