The File - Oct 1, 2008 - (Page 9)

In Focus | Wireless Networking Fine-tuning RF platform shrinks design time By Mahesh Kiwalkar Wireless Staff Applications Engineer Cypress Semiconductor Corp. As wireless technology continues to evolve, more and more wireless IC solutions are becoming available in the marketplace, making them almost ubiquitous. Once a particular wireless technology is selected, wireless radio module OEMs face the challenging task of incorporating the radio IC into their application. Selection of the right wireless IC can reduce engineering demands and accelerate time-to-market of the radio module. Beyond the technical specifications of competing IC solutions, the availability of the right development platform plays a big role in this selection process. Every manufacturer of wireless electronic equipment must meet regulator y standards where the equipment will be sold or used. Radio compliance is one of the major hurdles for wireless OEMs, and the sooner this is addressed in the design cycle, the faster the OEM can move towards product launch. Typically an OEM designs a module around a wireless IC and once the design nears completion, it has to develop test firmware and hardware to test the radio module. This approach adds to the total development time and cost, and can yield catastrophic results. Thinking about radio compliance at the very end of the development cycle also increases the ROI risk considering the possibility of an unforeseen regulatory spec failure. Hence systematic design for compliance is vital to reducing retesting costs required by noncompliance and to accelerating revenue realisation from new products. Having an RF development platform available during the design and development phase with the necessary firmware to test radio transceiver parameters Figure 1: Test set-up for simulated range measurements. speeds up prototype development stages in a sequential and progressive manner. Modifications can be made in the design during prototyping stages to accommodate any performance issues. This approach also offloads the OEM’s responsibility to develop the test platform for the specific radio module. Such an RF development platform that also covers the regulatory pre- part of the firmware running on the test platform and the other half running on the CPU that interfaces with the radio. In this manner, multiple RF tests can be carried out in a single hardware set-up by issuing commands from the RF test platform to the OEM radio module over the wireless link itself. Furthermore, if this RF development platform is to be used across multiple From the OEM’s perspective, the RF development platform should double up as a pre-compliance test platform for specific regulatory tests. certification tests before going to final compliance testing drops the OEM’s ROI risk considerably. wireless ICs from the same vendor, as long as this firmware code snippet is run on the CPU that interfaces to the radio, you are good to go. During the design cycle, such an RF development platform provides a means of testing range with a limit of operating condition. Packet data can be sent by the test kit to the DUT over the wireless link. The firmware running on the DUT simply echoes the data back to the test kit. Based on the data received, the RF test platform calculates the packet error rate (PER) for the transmit-receive sequence. Since the range for a wireless device doubles with every 6dB of reduced path loss, a step attenuator can be connected in series with the test set and range testing can thus be simulated. The step attenuator progressively adds attenuation to the link budget—thus with increasing attenuation, PER gets worse and a point is reached when the device and the platform stop talking to each other. This provides a very simple and reliable method for carrying out comparative evaluation of various prototype stages. RF essentials From the OEM’s perspective, the RF development platform should accomplish majority of the basic transceiver tests and double up as a pre-compliance test platform for specific regulatory tests. It should have a simple serial port interface to any readily available terminal program such as HyperTerminal or ProComm. This obviates the need to purchase expensive software and cuts down on the software learning curve considerably. The idea is to have DUT orientation Performance of the RF module depends largely on the orientation of the DUT (and hence the antenna) inside the anechoic chamber. Antenna design with good radiation patterns becomes a significant part of RF module design. Before taking the final module to the test house for getting accurate antenna radiation pattern plots, it would be economical and highly beneficial to get an approximate idea of the radiation characteristics. This is where the RF development platform steps in. The RF platform is connected to the attenuator, which in turn is connected to the rubber duck antenna inside the anechoic chamber (figure 1). The DUT is placed inside the chamber at the continued on page 1 9 EE Times-India | October 1-15, 2008 | www.eetindia.com http://www.eetindia.co.in/SEARCH/SUMMARY/technical-articles/radio.HTM?ClickFromNewsletter_081001 http://www.eetindia.co.in/SEARCH/SUMMARY/technical-articles/CPU.HTM?ClickFromNewsletter_081001 http://www.eetindia.com/STATIC/REDIRECT/Newsletter_081001_EETI02.htm?ClickFromNewsletter_081001

Table of Contents for the Digital Edition of The File - Oct 1, 2008

EETimes India - October 8, 2008
National Semiconductor
Tech Insights
Trends
Cadence
Texas Instruments
Fine-tuning RF Platform Shrinks Design Time
DigiKey
Mobile WiMAX Enables IP Convergence

The File - Oct 1, 2008