Testing symmetrical 2.4 GHz ZigBee transceivers using unsymmetrical RF measurement equipment

The 2.4 GHz ISM band is well suited for short range data transmission. In addition to proprietary solutions different standards have been established: WLAN, Bluetooth^® and ZigBee™. To improve the EMC parameters of radio modules symmetrical topologies using differential signals have been introduced. Since the majority of test and measurement equipment has single ended inputs with coaxial connectors (except VNAs) there is a gap between measurement, test equipment and application. Based on the development of a load board for a ZigBee transceiver by Atmel^® the way of solving this conflict will be shown. The focus is set on the issues of RF transmission lines including the step from planar to coaxial structures, RF contact systems and calibration and de-embedding procedures. The influence and frequency response of the RF wiring to the tester instruments has been reduced. The realized accuracy of RF parameters measured on the load board is presented. Applications for these RF ICs are wireless data transmission in general and wireless sensor networks [11].