The requirements of modern communication systems is smaller, faster, lower power, more powerful and less interference. The combination of the M-ary digital communications technology and design of modern electronic communication systems stimulate the rapid development of the performance of the communication system. The increasing development of the large-scale programmable devices CPLD / FPGA integration, functionality and speed just to meet the requirements of modern communication systems.
This paper describes the QPSK digital communications modulation principle, design QPSK modulation by using the CPLD chip. In the MAX + plus Ⅱ environment programming using VHDL language and simulated to obtained waveforms and used oscilloscopes and debugging of the circuit board to compare the waveform to verify the correctness of the design. The design study the principle experiment on the expansion of communication that is very meaningful and has high practical value.