Design and Implementation of Frequency Synthesizer
Wang Shuai · Journal of North China Institute of Water Conservancy and Hydroelectric Power · 2012
Direct digital synthesis(DDS) is a technology of using digital processing modules to generate output signals whose frequency and phase can be adjusted,which takes a fixed-frequency precision clock source as the reference.To realize DDS,a design scheme of frequency synthesizer is presented taking DDS chip 8254 of American Intel Corporations and AT89C51 of ATEML Corporations as the core components.Users can input the frequency data through a dial switch,and the microcontroller reads the relevant value of the frequency tuning word(FTW) and inputs it into the DDS chip.Then the output frequency hopping will be achieved by changing the FTW address in the ROM table.At the same time,a low pass filter and an amplifier are added on the output end of DDS,which can suppress the spurious noise but enlarge the output signal simultaneously.Finally,the required output waveform is obtained.