Datasheet

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.