The GC5316 is a high-density multi-channel communications signal processor integrated circuit that provides both digital downconversion and 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 downconverter (DDC) and digital upconverter (DUC) channels or 12 UMTS DDC and DUC channels. The GC5316 can also support a combination of CDMA and UMTS channels. The DDC and DUC channels are independent and 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. On the DDC side there are four 16 bit input ports that can accept real or complex input data. The input ports are driven with parallel data, typically from an analog-to-digital converter. Each downconverter channel can be programmed to accept data from any one of the four input ports.