FCC Primer for Amplified 802.15.4 / 2.4GHz DSSS Applications

This application note focuses on FCC compliance limits for 2.4GHz DSSS radios being utilized in ZigBee-compliant and non-ZigBee-compliant DSSS platforms. Integrated 2.4GHz transceivers and SoC (System on Chip) radios allow engineers to quickly implement radio designs following manufacturers' data sheets and application notes. Application-specific PAs and integrated RF front ends also enable increased performance by mating a PA or various combinations of integrated balun, PA, LNA and T/R switch to the single-chip radio. This produces a simple yet powerful design. The FCC limits stated in 47CFR 15.247 allow for a maximum of 1W conducted RF power output and up to a +6dBi antenna gain. This document will outline significant limitations in achieving TX output power to assist the engineer in investigating relevant factors before bringing the product to the certification lab.