User's Manual
Table Of Contents
- 1 Introduction
- 2 Disclaimer
- 3 Overview
- 4 Functional description
- 5 PCB layout description
- 6 Mechanical description
- 7 Electrical characteristics
- 8 Abbreviations
- References
- EVALUATION BOARD/KIT IMPORTANT NOTICE
- 9 Table of contents
Atmel AVR2092
11
8427A-AVR-10/11
5.1 PCB detail 1 – balanced RF pin fan out
Figure 5-2. Board layout – RF pin fan out.
The Atmel AT86RF232 antenna port should be connected to a 100 load with a small
series inductance of 1nH to 2nH. This is achieved with the connection fan out in
between the IC pins and the filter balun combination B1. The trace width is kept small
at 0.2mm for a length of approximately 1.5mm. The REB232ED is a two-layer FR4
board with a thickness of 1.5mm. Therefore, the distributed capacitance between top
and bottom is low, and transmission lines are rather inductive.
B1 has the DC blocking built in. Only pin 2 requires DC blocking within its GND
connection since this is considered as bias access pin.
The distance of 1.5mm also allows GND vias for pin 3 and pin 6 of the AT86RF232.
Such a low inductance GND connection is really desirable for the RF port.