Integrating wireless communications with microprocessor based products

Almost since their emergence, microprocessors have been integrated into radio communications products. Today that trend has largely been reversed in the off-the-peg radio communications modules: GSM, GPRS, GPS, 3G, WLAN and Bluetooth are being integrated into a wide variety of microprocessor based products. This paper discusses the EMC aspects of such integrations from conventional narrow-band to modern spread-spectrum techniques. There are two goals for the designer: (i) to prevent the communications module and microprocessor interfering with each other (internal EMC) and (ii) to comply with the appropriate market access legislation (external EMC). Both issues are essential in getting reliable products to market but only the former is considered here. A systematic design approach for the successful integration of radio and microprocessor devices is proposed. The different implications on microprocessor design of narrow-band and spread spectrum communications are investigated. Similarly the affect of the spread-spectrum clocking of microprocessors on radio receivers is discussed.