EVAL-AD5933EB Datasheet, PDF (34/40 Pages) Analog Devices – 1 MSPS, 12-Bit Impedance Converter, Network Analyzer

AD5933
LAYOUT AND CONFIGURATION
POWER SUPPLY BYPASSING AND GROUNDING
When accuracy is important in a circuit, carefully consider the
power supply and ground return layout on the board. The
printed circuit board containing the AD5933 should have
separate analog and digital sections, each having its own area
of the board. If the AD5933 is in a system where other devices
require an AGND-to-DGND connection, the connection
should be made at one point only. This ground point should
be as close as possible to the AD5933.
The power supply to the AD5933 should be bypassed with
10 µF and 0.1 µF capacitors. The capacitors should be physically
as close as possible to the device, with the 0.1 µF capacitor
ideally right up against the device. The 10 µF capacitors are
the tantalum bead type. It is important that the 0.1 µF capacitor
have low effective series resistance (ESR) and effective series
inductance (ESI); common ceramic types of capacitors are
suitable. The 0.1 µF capacitor provides a low impedance path
to ground for high frequencies caused by transient currents
due to internal logic switching.
Data Sheet
The power supply line itself should have as large a trace as
possible to provide a low impedance path and reduce glitch
effects on the supply line. Clocks and other fast switching
digital signals should be shielded from other parts of the board
by digital ground. Avoid crossover of digital and analog signals
if possible. When traces cross on opposite sides of the board,
ensure that they run at right angles to each other to reduce
feedthrough effects on the board. The best board layout
technique is the microstrip technique where the component
side of the board is dedicated to the ground plane only, and the
signal traces are placed on the solder side. However, this is not
always possible with a two-layer board.
Rev. E | Page 34 of 40