Phase 2: Components Placement; Phase 3: Routing; Basic Hints; Layout Specific Hints - Panasonic eUniStone Application Note Design Manual


Blind via: they are drilled from an outer layer to one of the inner layers. Blind via are most efficient if
used with buried via. The diameter is ≥ 100 m.
Through via: they are drilled from the top layer to the bottom layer, and have a typical diameter of
200-300 m, all the inner layers can be connected to the via. Often are used to connect all the ground
areas in the different layers.
When a trace that carry high current moves from one layer to another, more parallel via are required.
Placing more via reduce the resistance of the overall connection.
Too high resistance in the power trace might lead to a not constant supply in TDMA system where the
TX section is switched on only during the TX slot: when the power section is on, the IC is drawing high
current, which produce a voltage drop in the trace, the supply is AM modulated, which ultimately
might affect all the performances of the IC.
7.2.2

Phase 2: Components Placement

Placement of the components must be done following the order:
1. Place the connectors in the most rational way considering power distribution and
interfaces.
2. Place the eUniStone module with the antenna on the edge of the PCB.
Place all the other components in order to minimize track length and –if possible- keeping separate
high frequency and baseband sections.
7.2.3

Phase 3: Routing

7.2.3.1

Basic Hints

Here are some basic hints on routing to avoid crosstalk. These are golden rules not only applicable to
eUniStone, but to all designs:

Group and route traces according to their functionality. Start routing high frequency
lines and other sensitive lines.

Minimize the length of parallel routed traces, in the same layers and in adjacent
layer. In adjacent layers orthogonal routing – alternating horizontal and vertical
routed layer – is helpful to avoid capacitive coupling between traces on different
layers.

Keep enough separation between traces.
7.2.3.2

Layout Specific Hints

Mid layer 1 should be used as a ground plane:
Application Note
Design Guide
48
PAN1322
Revision 1.2, 2013-12-18