Direct Digital Synthesis with Fractional Tuning

This paper presents a new approach to the design of direct digital frequency synthesizer (DDS) with possibility of fractional frequency tuning. Such DDS has advantage if small number of bits for phase accumulator is used. A new DDS frequency synthesizer was designed to enable using fractional frequency tuning word (FTW) is proposed, which improves the accuracy of synthesized signals therefore better resolution and reach output frequency which is a closer to desired frequency. The DDS was designed, simulated and implemented in microcontroller.