GC5318,pdf(High-Density Digita

The GC5318 is a high-density multi-channel communications signal processor integrated circuit that
provides digital upconversion optimized for cellular base transceiver systems. The device supports both
UMTS and CDMA2000 (CDMA) air interface cellular standards.
The chip provides up to 24 CDMA digital upconverter (DUC) channels or 12 UMTS DUC channels. The
GC5318 can also support a combination of CDMA and UMTS channels. The DUC channels operate
simultaneously.
The chip is ideal for cellular base transceiver systems where a large number of digital radio channels are
required. Each of the 24 CDMA (or 12 UMTS) channels can operate independently.
There are four 18-bit output ports. Each output port can sum any of the DUC channels in a daisy-chain
fashion. This configuration permits creating a stack of CDMA or UMTS signals. These ports can output
either real or complex data. Real output data would generally drive one or more digital-to-analog (D/A)
converters and output the stack of signals at an intermediate frequency (IF). Complex data (at baseband
or an IF) is used when a quadrature modulator upconversion scheme is employed. Complex output data
can also be used when the output stack is further processed using crest factor reduction or power
amplifier predistortion techniques.