A novel implementation of QPSK modulator on FPGA

QPSK is one of the digital modulation techniques in communication system that has wide applications in the field of wireless, satellite communication, Bluetooth, OFDM etc. The Conventional QPSK modulators designs are generally based on IQ approach. In these modulators multipliers are used to separate the modulating signal into the in-phase and quadrature phase which increases the hardware complexity. The objective of this work is to implement the digital QPSK modulator with conventional and another approach of digitization. In this approach a digitized carrier wave is generated and QPSK phase shifting is provided by 4:1 multiplexer according to the data bits. The implementations of both the designs are done on Spartan 3E Xilinx FPGA through the verilog hardware description language. The QPSK modulator based on the Digitized approach is simpler in terms of hardware circuitry.