This work proposes a communication digital signal processor (DSP) suitable for massive signal processing operations in orthogonal frequency division multiplexing (OFDM) and code-division multiple-access (CDMA) communication systems. The OFDM-based IEEE 802.11a wireless LAN transceiver and CDMA-based WCDMA uplink receiver are simulated to evaluate the computation requirements of future communication systems. The architecture of the communication digital signal processor is established according to the computational complexity of these simulations. The proposed architecture supports basic butterfly operations, single/double-precision and real- and complex-valued multiplication-and-accumulation (MAC), squared error computation, and add-compare-select (ACS) operation. This butterfly/complex MAC architecture can greatly enhance the execution efficiency of operations often found in communication applications. The processor chip is fabricated using a 0.35-μm n-well one-poly four-metal CMOS technology. The fabricated DSP chip reaches a speed of 1.1 G MAC/s when operating in the high-speed mode, and it achieves 4 M MAC/s/mW in the low-power mode.