1. 1 Direct Digital Synthesizer STUDENT ： Tsung-Han Tu SN ： M9720112

2. 2 Direct Digital Synthesizer(1/2)  The DDS is constructed by a ROM with many samples of a sine wave stored in it.  The DDS produces sinusoidal signal. The frequency of the output signal for a n-bit system is determined by ：

3. 3 Direct Digital Synthesizer(2/2) Fig. 1 Block diagram of a DDS system.

4. 4 Multiple frequencies from a single DDS(1/3)  Instead of using only one frequency setting word (FSW) three of them are employed.  The formula, which gives the output frequency.

5. 5 Multiple frequencies from a single DDS(2/3)  Two non-consecutive outputs of the line decoder are used for the generation of the 57 KHz signal. Fig. 4 Block diagram of a multiplexed DDS system.

6. 6 FPGA

7. 7 Multiple frequencies from a single DDS(3/3)  Waveforms produced at the three outputs of the multiplexed DDS. Fig. 5 From top to bottom the 19KHz, 57KHz and 38KHz waveforms.

8. 8 Thanks