Nowadays frequency synthesizers are widely used in all forms of radio communication devices. They are essential part of cellular phones, televisions, signal generators, spectrum analyzers and much more professional radio devices. A frequency synthesizer is capable of generating a signal with an exact frequency in a wide band from a fixed reference signal. In the recent years with the widespread use of digital techniques in instrumentation and communications systems, a digitally-controlled method of frequency synthesis has developed called Direct Digital Synthesis (DDS). The DDS operates by storing various points of a waveform in digital form and then recalling them to generate the waveform. DDS is often used in conjunction with indirect or phase locked loop synthesizer loops. The aim of my thesis was to develop a Direct Digital Synthesis based circuit which is capable of generating signals in the 100-400 MHz frequency range and do some research about how it can be used in fast frequency synthesizers. Thorough my work I got acquitted with designing printed circuit board, programming a microcontroller, designing a graphical user interface using C# programming language. I had to do numerous measurements such as spurious signals, phase noise, signal accuracy measurements. I completed the proposed task. The circuit operates according to the technical specifications. I performed my task at BHE Bonn Hungary Electronics Ltd. in Budapest, for the design and tests I used the tools assured by the company.