Universal Global Scientific Industrial Co. Ltd. VZ22Q Manuale Utente
VZ22Q LTE Module
V0.1
USI
Confidential
Page 17 of 23
5.2 Component Placement
For a layout that helps to reduce noise, separate analog and digital ground planes should be
provided, with the digital components over the digital ground plane, and the analog components,
including the analog power regulators, over the analog ground plane. In addition to ground
planes scheme, digital and analog power supply planes should be partitioned directly over their
respective ground planes. It should be place analog power coincident with analog ground planes,
and digital power coincident with digital ground planes (as Figure. 5-2 – “RIGHT” separation).
If any portions of analog and digital plane overlap, the distributed capacitance (result from
power plane reference to ground plane or signal plane reference to ground plane) between the
overlapping portions will couple digital noise into the analog circuitry. This defeats the purpose
of isolated plane (as Figure. 5-3 – “WRONG” separation). The power and ground planes should
be separated by approximately 40mils for the four layer PCB design. Using power and ground
planes forming a natural, high capacitive, bypass capacitor to reduce overall PCB noise.
including the analog power regulators, over the analog ground plane. In addition to ground
planes scheme, digital and analog power supply planes should be partitioned directly over their
respective ground planes. It should be place analog power coincident with analog ground planes,
and digital power coincident with digital ground planes (as Figure. 5-2 – “RIGHT” separation).
If any portions of analog and digital plane overlap, the distributed capacitance (result from
power plane reference to ground plane or signal plane reference to ground plane) between the
overlapping portions will couple digital noise into the analog circuitry. This defeats the purpose
of isolated plane (as Figure. 5-3 – “WRONG” separation). The power and ground planes should
be separated by approximately 40mils for the four layer PCB design. Using power and ground
planes forming a natural, high capacitive, bypass capacitor to reduce overall PCB noise.
Figure. 5-2 Side view of PCB, the “Right” separation of analog and digital plane.
Figure. 5-3 Side view of PCB, the “Wrong” separation of analog and digital plane.