NORWOOD, Mass. -- A partnership between Analog Devices Inc. and Mitsubishi Electric Corp. of Japan has produced a direct-conversion radio chip for use in 3G cellular handsets for the W-CDMA (Wideband Code Division Multiple Access) standard.
Direct conversion, otherwise known as "zero IF," eliminates the intermediate frequency section of traditional radio technologies. Direct conversion enables radio designers to take a high frequency or RF input signal directly to baseband or low frequencies, eliminating scores of components and significantly boosting efficiency, according to the companies.
"We chose Analog Devices for this chip development because they have excellent analog designers and radio systems engineers," said Kenji Itoh, section manager for the Next-Generation Radio Terminal Development Department of Mitsubishi Electric. "Our W-CDMA handset will be very competitive in the market due to the direct-conversion architecture. It will be smallerand lower cost than others."
"Using direct conversion for demanding radio systems like GSM and W-CDMA requires expertise in analog design as well as a complete system understanding," said Christian Kermarrec, vice president of RF and wireless systems at Analog Devices. "We are extremely pleased to have Mitsubishi as our partner in this development."
Analog Devices introduced its patent-pending direct-conversion feature in its Othello chip set last year (see Sept. 15, 1999 story).
The new 3G radio chip, which will be described in detail in a paper at the RFIC Symposium in June, includes variable-gain amplifiers, baseband channel filters, and a wide-dynamic-range logarithmic amplifier for RSSI (Received Signal Strength Indication) detection. It is extremely low in power consumption, and is manufactured in Analog Devices' BiCMOS process. In addition, the direct conversion architecture greatly simplifies the radio design, eliminating most of the expensive oscillators and filters required by conventional receivers, ADI said.