PC BOARD LAYOUT CONSIDERATIONS
The ADV7120 is optimally designed for lowest noise perfor-
mance, both radiated and conducted noise. To complement the
excellent noise performance of the ADV7120, it is imperative
that great care be given to the PC board layout. Figure 8 shows
a recommended connection diagram for the ADV7120.
The layout should be optimized for lowest noise on the
ADV7120 power and ground lines. This can be achieved by
shielding the digital inputs and providing good decoupling. The
lead length between groups of VAA and GND pins should by
minimized so as to minimize inductive ringing.
The ADV7120 and associated analog circuitry, should have a
separate ground plane referred to as the analog ground plane.
This ground plane should connect to the regular PCB ground
plane at a single point through a ferrite bead, as illustrated in
Figure 8. This bead should be located as close as possible
(within 3 inches) to the ADV7120.
The analog ground plane should encompass all ADV7120
ground pins, voltage reference circuitry, power supply bypass
circuitry, the analog output traces and any output amplifiers.
The regular PCB ground plane area should encompass all the
digital signal traces, excluding the ground pins, leading up to
ANALOG POWER PLANE
L1 (FERRITE BEAD)
ANALOG GROUND PLANE
L2 (FERRITE BEAD)
C3, C4, C5, C6
R1, R2, R3
33µF TANTALUM CAPACITOR
10µF TANTALUM CAPACITOR
0.1µF CERAMIC CAPACITOR
75Ω 1% METAL FILM RESISTOR
560Ω 1% METAL FILM RESISTOR
1.235V VOLTAGE REFERENCE
VENDOR PART NUMBER
FAIR-RITE 274300111 OR MURATA BL01/02/03
ANALOG DEVICES AD589JH
Figure 8. ADV7120 Typical Connection Diagram and Component List