Software radiom devices

[prinaldo@mindspring.com]

Gang, FYI, Paul

3/20/01 10:34:00 PM — Analog Devices, Inc. (ADI) has launched a new family of versatile communications processors for use in the software radio implementation
              of products based on multi-carrier, multi-mode architectures for receiving as well as
              transmitting digital signals. Offering an intriguing alternative to the use of an ASIC
              or FPGA, the new 'VersaComm' devices have been designed to perform the digital
              filtering and frequency conversion functions in high-speed cellular base stations. In
              addition, the devices may also be gainfully employed in a variety of other
              applications, including cellular E911 location services, wireless local loop, phased
              array antennas, digital video, communications test equipment, and ultrasound. 

              According to Donald Chue, Business Development Manager for Wireless
              Infrastructure Products, the VersaComm family gives OEMs some field-configurable
              alternatives for meeting their digital mixing and filtering requirements in ways that
              are less expensive than an FPGA implementation and more flexible than an ASIC
              solution. The devices can also perform frequency-conversion and filtering
              operations more efficiently, says Chue, while consuming less power and physical
              space than their aforementioned marketplace alternatives. 

              Forming part of ADI's Softcell transceiver chipset, the VersaComm family of devices
              has been optimized for use with the company's high-speed IF-sampling ADCs and
              TxDACs. However, the devices may also be integrated with other products
              manufactured by third-party vendors. In addition, Chue says that ADI intends to
              make available the talents of its in-house staff of wireless design engineers in
              order to assure that designers are able to obtain the VersaComm devices they
              need to fulfill the specific requirements of software radios and other products. 

              Chue claims that designers using VersaComm devices can substantially reduce the
              masking investment and the on-going support costs that their companies must
              otherwise absorb when designing their own ASICs in-house. In addition, Chue
              believes that those designers who use a DSP for enabling the same functions that
              a VersaComm product could provide are needlessly consuming valuable DSP
              resources that otherwise could be more profitably dedicated to handling base-band
              operations. 

              The VersaComm family currently includes three RSP (receive signal processor)
              devices that are capable of performing the tuning, quadrature mixing, channel
              select filtering and data decimation functions in digital wireless base station
              applications, where they replace analog selectivity and tuning functions with digital
              equivalents. Generating 65 and 80 million samples per second (MSPS), the AD6620
              and AD6624 are single/dual channel devices for use in products based upon the
              EDGE, GSM, IS-95 and IS-136 standards. In addition, an 80-MSPS
              single/dual/quad-channel RSP called the AD6634 is available that offers various
              extensions in support of the 3G wireless standard. 

              Two VersaComm TSP (transmit signal processor) devices are also on tap for the
              performance of data interpolation, quadrature modulation, frequency tuning, pulse
              shaping and pulse filtering. Each TSP defines the variable channel characteristics in
              terms of channel bandwidth, channel shape, and data rate. Both the 75-MSPS
              AD6622 and the 104-MSPS AD6623 offer their support for the EDGE, GSM, IS-95
              and IS-136 cellular standards. In addition, the AD6623 provides non-integer
              re-sampling as well as extensions in support of GSM/EDGE and IS-95 operations. 

              The VersaComm family is rounded out by three QDUC (quadrature digital
              upconverter) devices. The 200-MSPS AD9856 with 12-bit DAC is primarily for use as
              a universal upstream and downstream I/Q modulator for hybrid fiber coax (HFC)
              cable network applications. The 200-MSPS AD9857 with 14-bit DAC can either
              function as a universal I/Q modulator and agile upconverter, single-tone
              direct-digital synthesizer (DDS) or interpolating DAC. Also available: a quadrature
              phase-shift-keying 16-QAM digital modulator with 10-bit DAC.