"As we enter the third generation (3G) of the wireless market, engineers are looking for new ways to develop the RF section of their system designs. The software radio is one solution that has been tossed around by many industry players. By performing RF functionality in software, engineers feel they develop wireless products that can quickly be adjusted to handle changes to a standard or to support an entirely different air interface.
"Recognizing this need, Upper Saddle River, NJ-based Pentek has unleashed a digital upconverter/digital-to-analog converter (DAC) module. According to Pentek, engineers can use this module, dubbed model 6229, to create a complete transmit/receive software radio system for next-generation base station design.
"Model 6229 is a Velocity interface mezzanine (VIM) module that attached directly to VIM-compatible digital signal processor (DSP) boards. The digital upconverter/DAC module contains two complete upconverter channels, each accepting wideband digital baseband input signals and generating frequency-translated analog IF output signals up to 80 MHz.
"Both upconverter channels use the AD9856 quadrature digital upconverter, which includes half-band and CIC interpolation filters, a programmable local oscillator, a complex mixer, and a 12-b DAC. The AS9856 also sports an on-chip multiplier that accepts a reference clock from 10 to 50 MHz and multiplies it to a 200 MHz internal sampling clock.
"The digital upconverter accepts complex baseband digital inputs with bandwidths as high as 22.5 MHz, supporting emerging wideband CDMA (W-CDMA) standards. Complex baseband signals are delivered into the 6229 module through a 32-b parallel FIFO. Data may be packed with both I and Q components in a single 32-b word for more efficient transfers.