User Manual

datasheet
Version 0.9
2017-09-13
deRFsamR21E-23S00/-23S20 datasheet
www.dresden-elektronik.de
Page 21 of 36
9. Application Information
The PCB design of a radio module base board is important for a proper performance of
peripherals and the radio. The next subsections give design hints to create a custom base
board.
9.1. PCB Technology
The module is designed for use with standard PCB technology to reduce the costs and cover
a wide application range.
9.2. Power supply
Power supply pins 13 and 14 have to be connected to a power domain of 2.5 to 3.6 V. No
external decoupling components are needed. For noisy environments it is recommended to
include a filter consisting of a ferrite or inductor and capacitors to reduce noise on the power
domain to the module. An example is shown in Figure 11-1. Place all components in near
proximity to each other and C2 between Pin 14 and 15 next to the module.
Figure 11-1: Power supply decoupling for noisy environments
9.3. Ground plane
The performance of RF applications mainly depends on the ground plane design. The often
used chip ceramic antennas are very tiny, but they need a proper ground plane to establish a
good radiation pattern. Every board design is different and cannot easily be compared to
each other. Some practical notes for the ground plane design are described below:
Regard to the design guideline of the antenna manufacturer
Use closed ground planes on the PCB edges on top and bottom layer
Connect the ground planes with lots of vias. Place it inside the PCB like a chessboard
and on the edges very closely.
9.4. Layers
The use of 2 or 4 layer PCB boards have advantages and disadvantages for the design of a
custom base board.
Table 11-1: 2 and 4 layer board properties in comparison
2 Layer board
4 Layer board
(-) only 2 layers available for routing traces and
design a proper ground area
(+) 4 layers available for routing traces and
design a proper ground area
(-) only 1 layer available for routing traces
below the module
(+) 3 layers available for routing traces
below the module