MC33596_10 Datasheet, PDF (62/70 Pages) Freescale Semiconductor, Inc – PLL Tuned UHF Receiver for Data Transfer Applications

PCB Design Recommendations
21 PCB Design Recommendations
Pay attention to the following points and recommendations when designing the layout of the PCB.
• Ground Plane
— If you can afford a multilayer PCB, use an internal layer for the ground plane, route power
supply and digital signals on the last layer, with RF components on the first layer.
— Use at least a double-sided PCB.
— Use a large ground plane on the opposite layer.
— If the ground plane must be cut on the opposite layer for routing some signals, maintain
continuity with another ground plane on the opposite layer and a lot of via to minimize
parasitic inductance.
• Power Supply, Ground Connection and Decoupling
— Connect each ground pin to the ground plane using a separate via for each signal; do not use
common vias.
— Place each decoupling capacitor as close to the corresponding VCC pin as possible (no more
than 2–3 mm away).
— Locate the VCCDIG2 decoupling capacitor (C10) directly between VCCDIG2 (pin 14) and
GND (pin 16).
• RF Tracks, Matching Network and Other Components
— Minimize any tracks used for routing RF signals.
— Locate crystal X1 and associated capacitors C6 and C7 close to the MC33596. Avoid loops
occurring due to component size and tracks. Avoid routing digital signals in this area.
— Use high frequency coils with high Q values for the frequency of operation (minimum of 15).
Validate any change of coil source.
NOTE
The values indicated for the matching network have been computed and
tuned for the MC33596 RF Modules available for MC33596 evaluation.
Matching networks should be retuned if any change is made to the PCB
(track width, length or place, or PCB thickness, or component value). Never
use, as is, a matching network designed for another PCB.
MC33596 Data Sheet, Rev. 4
62
Freescale Semiconductor