This invention is an application specific integrated processor to implement the complete fixed-rate DRX signal processing paths (FDRX) for a reconfigurable processor-based multi-mode 3G wireless application. This architecture is based on the baseline 16-bit RISC architecture with addition functional blocks (ADU) tightly coupled with the based processor's data path. Each ADU accelerates a computation-intensive tasks in FDRX signal path, such as multi-tap FIRs, IIRs, complex domain and vectored data processing. The ADUs are controlled through custom instructions based on the load/store architecture. The whole FDRX data path can be easily implemented by the software employing these custom instructions.